World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/shrew): Shrew — wildlife guide.

## Why do shrews eat so much?
Shrews have one of the highest metabolic rates of any mammal, a consequence of their tiny bodies. Small animals lose heat rapidly because they have a large surface area relative to their volume, so a shrew must burn fuel at a furious pace simply to stay warm. To keep that internal furnace stoked, shrews eat almost continuously, day and night, in short bursts of activity separated by brief rests. In captivity some shrews consume between half and twice their own body weight in food every day. Their diet is dominated by invertebrates such as insects, larvae, earthworms, spiders, woodlice and snails, though some take small amounts of seeds or carrion. This relentless appetite has a stark consequence: many shrews can starve to death within a matter of hours if they cannot find food, and they rarely survive long without eating. Their hearts beat extraordinarily fast and they remain active through much of winter rather than hibernating, because stopping to sleep deeply would risk running out of energy entirely. Constant feeding, in short, is not greed but survival.

## Are shrews venomous, and can they hurt people?
A small number of shrew species are genuinely venomous, which is remarkable because venom is rare among mammals. The venom is delivered through grooves in the teeth via the saliva, and is used to subdue prey rather than for defence. In the American short-tailed shrew, the venom is potent enough that, in laboratory studies, the quantity from a single animal has been measured as sufficient to kill many small rodents by injection. The venom helps shrews tackle prey larger than themselves and, in some species, may even allow them to paralyse and store live invertebrates for later. For humans, shrews pose very little danger. They are tiny, secretive and not aggressive towards people, and a bite from a venomous species would at most cause local pain and swelling rather than serious harm. Far from being a threat, shrews are valuable allies in gardens and farmland, where their voracious appetite for insects, slugs and other invertebrates helps keep populations of garden pests in check throughout the year.

## Why do cats kill shrews but not eat them?
Cat owners often find a dead shrew left as an uneaten 'gift' on the doorstep, and the reason lies in the shrew's chemistry. Shrews possess scent glands, particularly on their flanks, that produce a strong, musky, distasteful odour. Cats are highly motivated to hunt small moving animals by instinct, so they readily catch and kill shrews, but the unpleasant smell and taste usually stop them from actually eating the catch. The result is a steady supply of intact shrew bodies delivered by domestic cats but left untouched. This behaviour is so consistent that cat predation is a recognised pressure on local shrew populations in some areas. Beyond cats, shrews fall prey to owls and other birds of prey, which have a poorer sense of smell and are far less deterred by the scent, making them among the shrew's most important natural predators. The same defensive odour that frustrates a cat does little to protect a shrew from a hunting owl swooping silently overhead at night.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/shrew): Shrew — wildlife guide.

## WARN work
World Animal Rescue Network does not run field projects dedicated specifically to shrews, which are widespread and mostly secure, and most live well outside the countries where WARN's partners work partner countries. This guide is part of WARN's free educational work, which aims to make accurate, well-sourced wildlife information freely available to everyone. The threats that touch shrews most, chiefly habitat loss, pesticide use and the decline of insect prey, are the same pressures bearing down on many of the animals WARN does directly protect.

## Donation hook
If our free wildlife guides help you see small creatures like the shrew a little more clearly, a small gift helps us keep this knowledge open to all and support the animals in our care.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/shrew): Shrew — wildlife guide.

## Is a shrew a mouse or a rodent?
Neither. A shrew is not a rodent and is not closely related to mice, despite looking similar. Shrews belong to the order Eulipotyphla and are relatives of moles and hedgehogs, while mice are rodents. You can tell them apart by the shrew's long pointed snout, tiny eyes and many small spike-like teeth, rather than a rodent's large gnawing front incisors.

## What is the smallest shrew, and the smallest mammal?
The Etruscan shrew is the smallest shrew and the smallest known land mammal by mass, weighing only about 1.8 grams and measuring around 3.5 centimetres in head-and-body length. It is so small it can rest in a human palm. Only certain bats rival it for the title of smallest mammal, and the Etruscan shrew remains the lightest terrestrial mammal known to science.

## Do shrews eat all the time?
Almost. Because of their tiny size and very high metabolism, shrews burn energy extremely fast and must feed in short bursts throughout the day and night. In captivity some eat between half and twice their own body weight in food daily. They feed mainly on insects, worms and other invertebrates, and can starve within a few hours if they cannot find enough to eat.

## Are shrews dangerous or venomous?
A few shrew species are venomous, delivering venom through their saliva to subdue prey, which is unusual among mammals. The American short-tailed shrew is a well-known example. However, shrews are not dangerous to people. They are tiny, shy and non-aggressive, and at worst a bite from a venomous species would cause minor local pain and swelling rather than any serious injury.

## Why does my cat bring me dead shrews but not eat them?
Shrews have scent glands that produce a strong, musky, unpleasant smell and taste. Cats hunt and kill them on instinct, drawn by the small moving animal, but are then put off eating them by the odour. This is why cats so often leave intact shrew bodies as uneaten 'gifts'. Owls, which have a weaker sense of smell, are far less deterred and readily eat shrews.

## How long do shrews live?
Shrews are short-lived animals. Most live only around 12 to 30 months, and few survive much more than a year in the wild. Their frantic metabolism, constant need to feed and heavy predation pressure all keep lifespans brief. Many shrews born in one year breed the following spring or summer and die soon after, so generations turn over very quickly compared with longer-lived small mammals.

## What do shrews eat?
Shrews eat Mainly insects and other invertebrates. A shrew is a small insect-eating mammal of the family Soricidae, with a long pointed snout, tiny eyes and velvety fur.

## Where do shrews live?
Shrews live in Almost worldwide; absent from Australia and most of South America. A shrew is a small insect-eating mammal of the family Soricidae, with a long pointed snout, tiny eyes and velvety fur.

## How big is a shrew?
A Shrew is about From ~3.5 cm (Etruscan shrew) to ~15 cm. A shrew is a small insect-eating mammal of the family Soricidae, with a long pointed snout, tiny eyes and velvety fur.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/mole): European Mole — wildlife guide.

## One-line answer
The European mole (Talpa europaea) is a small, burrowing insectivorous mammal with velvety fur, tiny eyes and powerful spade-like forepaws. It lives almost entirely underground, hunting earthworms in self-dug tunnels across Europe and western Asia, and is best known for the molehills it pushes to the surface.

## Introduction
The European mole (Talpa europaea) is a small, almost blind insectivore built entirely for life underground. Its cylindrical body, velvety fur and outsized spade-shaped forepaws let it shift soil with remarkable power, carving tunnel networks through gardens, pastures and woodland across much of Europe and into western Asia. Moles spend almost their whole lives below the surface, hunting earthworms in their tunnels, so they are rarely seen alive. Most people know them only by the molehills they leave behind. Despite their reputation as garden nuisances, moles aerate soil, control invertebrate pests and are listed as Least Concern by the IUCN, with stable populations across their broad range.

## Takeaway
The European mole is a subterranean insectivore, not a rodent, and spends almost its entire life underground.

## Takeaway
Its broad, outward-facing forepaws act like spades, letting it tunnel with great force through soil.

## Takeaway
Earthworms are its staple food; moles even store paralysed worms in underground larders for lean times.

## Takeaway
Molehills are simply the spoil heaps of excavated earth pushed up from tunnels below.

## Takeaway
Velvety fur that lies flat in any direction lets a mole move forwards and backwards through tight tunnels.

## Takeaway
The species is listed as Least Concern by the IUCN, with a large and stable population.

## What does a European mole look like and how is it adapted to digging?
The European mole is unmistakable in the hand, though seldom seen. It has a stout, cylindrical body 11-16 cm long, weighing roughly 70-130 g, with a short, club-shaped tail and no obvious neck. Its most striking feature is the pair of broad, paddle-like front paws, turned permanently outwards and tipped with strong claws. Powered by heavy shoulder and chest muscles, these act as living spades, pushing soil sideways as the mole drives forward. The fur is short, dense and velvety, and crucially has no set direction of lie, so it offers no resistance whether the animal moves head-first or reverses down a tunnel. Eyes are minute, around a millimetre across and hidden in the fur, giving only basic light detection; there are no external ear flaps. To compensate, the mole relies on an acute sense of touch and smell, including sensitive whiskers and a snout packed with tactile receptors that detect the tiny vibrations of prey moving through the soil. Every part of its anatomy is a refinement for a life spent burrowing in darkness.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/mole): European Mole — wildlife guide.

## What do moles eat, and why are earthworms so important?
Moles are carnivores with a near-insatiable appetite. Their staple prey is the earthworm, supplemented by insect larvae, beetles, centipedes and other soil invertebrates that fall into their tunnels. Rather than actively excavating to find food, a mole patrols its permanent tunnel system like a trap-line, eating worms that have burrowed through the walls. A mole must eat frequently to survive: it consumes roughly half its body weight in food each day and can starve within a day or so if deprived. One of its more remarkable behaviours is food caching. A mole's saliva contains a toxin that paralyses earthworms without killing them, and it bites the heads to immobilise them, stockpiling living worms in underground larders. Hundreds of worms have been found in a single store, kept fresh as a reserve against hard frosts or drought when foraging is difficult. This heavy reliance on earthworms explains why moles favour deep, moist, undisturbed soils such as pasture, deciduous woodland and gardens, and why they are scarce in very sandy, acidic or waterlogged ground where worms are few.

## Why do moles make molehills, and how do their tunnels work?
Molehills are the visible by-product of an invisible engineering project. As a mole digs and maintains its tunnel network, it must dispose of loosened earth, so it pushes the spoil up vertical shafts to the surface, creating the familiar conical heaps. A burrow system has two main levels: shallow surface runs used for foraging in soft, worm-rich soil, and deeper permanent tunnels that stay usable in dry or frozen conditions. The deep tunnels function as feeding traps, and a mole patrols them several times a day. Most moles are solitary and territorial, defending their networks against neighbours, though tunnels are sometimes inherited or shared after an occupant dies. Contrary to popular belief, the large mounds sometimes called fortresses are not always nests, but in cold or wet ground a mole may build a bigger chamber to raise young above the water table. Because moles aerate and mix the soil and prey on invertebrate pests, they are ecologically valuable, even where their excavations frustrate gardeners and farmers seeking a level lawn or field.

## Where do European moles live and are they endangered?
The European mole has a wide distribution, ranging across most of temperate Europe and into western Asia, from Britain and southern Scandinavia south to northern Greece and east towards western Siberia. It is notably absent from Ireland, where it never naturally colonised. Within this range it is common wherever soils are deep enough to dig and rich enough in earthworms, occupying farmland, grassland, gardens, parks and woodland. The species is assessed as Least Concern on the IUCN Red List, reflecting its large numbers and stable population trend; in Britain alone the population is estimated in the tens of millions. Moles are not listed by CITES and face no significant conservation threat at the species level. Localised declines can occur where intensive agriculture, soil compaction, pesticides or drainage reduce earthworm numbers, and historically many moles were trapped for their pelts and as agricultural pests. As a widespread, adaptable native mammal, however, the European mole remains one of the success stories of life beneath the surface.

## WARN work
WARN does not run field projects specifically for the European mole, which is a widespread, Least Concern species living mostly outside the countries where WARN's partners work. This guide is part of WARN's free educational mission to help people understand wildlife accurately. The same pressures that can locally harm moles, such as habitat loss, intensive land use and pesticide-driven declines in soil life, also threaten many of the animals WARN's partners do protect.

## Donation hook
If this guide helped you see the hidden world beneath your feet, a small gift helps keep WARN's free wildlife education and frontline animal care going.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/mole): European Mole — wildlife guide.

## Are moles blind?
Not completely. European moles have very small eyes, around a millimetre across and hidden in their fur, that can detect light and movement but form little useful image. Living underground in darkness, they rely far more on touch, smell and sensitivity to vibration than on sight, so they are best described as having very poor eyesight rather than being truly blind.

## Are moles rodents?
No. Despite digging like some rodents, moles are insectivores in the order Eulipotyphla, more closely related to shrews and hedgehogs than to mice, rats or voles. Unlike rodents, they do not have ever-growing gnawing incisors; their teeth are adapted for seizing and crushing earthworms and other soil invertebrates, which form the bulk of their diet.

## What do moles eat?
Earthworms are a mole's main food, supplemented by insect larvae, beetles, centipedes and other soil invertebrates. Moles eat roughly half their body weight each day and patrol their tunnels for prey that falls in. They also store living, paralysed earthworms in underground larders, using a mild toxin in their saliva to keep the worms immobile as a food reserve.

## Why do moles make molehills?
Molehills are heaps of spoil. When a mole digs or repairs its tunnel network, it must get rid of the loosened earth, so it pushes the soil up vertical shafts to the surface. The resulting conical mounds are simply waste from excavation, not nests, and a line of fresh molehills often traces the path of an active tunnel below.

## Are moles dangerous or harmful to gardens?
Moles are harmless to people and pets and do not eat plant roots or bulbs. They can disturb lawns, seedbeds and playing fields with their hills and shallow runs, which is why they are often seen as pests. On balance, though, they aerate and mix soil and eat many invertebrate pests, so their presence is a sign of healthy, worm-rich ground.

## Are European moles endangered?
No. The European mole is listed as Least Concern by the IUCN, with a large, stable population across Europe and western Asia and tens of millions estimated in Britain alone. It is not listed by CITES. Localised declines can follow intensive farming, soil compaction or pesticide use that reduces earthworms, but the species faces no significant overall conservation threat.

## Where do european moles live?
European moles live in Europe and western Asia; absent from Ireland. The European mole (Talpa europaea) is a small, burrowing insectivorous mammal with velvety fur, tiny eyes and powerful spade-like forepaws.

## How long do european moles live?
European moles typically live Typically 3-5 years. The European mole (Talpa europaea) is a small, burrowing insectivorous mammal with velvety fur, tiny eyes and powerful spade-like forepaws. Wild and captive figures can differ; use the sources listed on the guide for the underlying studies.

## How big is an european mole?
An European mole is about About 11-16 cm. The European mole (Talpa europaea) is a small, burrowing insectivorous mammal with velvety fur, tiny eyes and powerful spade-like forepaws. Conservation status: Least Concern (stable).


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/rat): Brown Rat — wildlife guide.

## One-line answer
A brown rat (Rattus norvegicus) is a large, adaptable rodent that lives alongside humans worldwide. Native to Asia, it has spread to every continent except Antarctica. Highly intelligent and social, it is the wild ancestor of both pet "fancy rats" and laboratory rats, and is listed as Least Concern.

## Introduction
The brown rat (Rattus norvegicus) is a stocky, blunt-nosed rodent that has become one of the most widespread mammals on Earth, found on every continent except Antarctica. Also called the common rat, Norway rat or sewer rat, it most likely originated in northern China and Mongolia before spreading along human trade routes worldwide. Highly intelligent, social and adaptable, it thrives wherever people live, from city sewers and farmland to ships and rubbish tips. The brown rat is the ancestor of both the affectionate pet "fancy rat" and the laboratory rat, making it one of science's most important animals. The IUCN lists it as Least Concern.

## Takeaway
The brown rat is among the most successful mammals alive, living wherever humans do across all continents except Antarctica.

## Takeaway
It most likely originated in northern China and Mongolia, despite the misleading name 'Norway rat'.

## Takeaway
Brown rats are highly intelligent, social animals that live in hierarchical groups and groom one another.

## Takeaway
They are the wild ancestor of both pet fancy rats and laboratory rats, central to modern medical research.

## Takeaway
The IUCN lists the brown rat as Least Concern, with a large and stable global population.

## Takeaway
As a non-native species in many regions, brown rats can threaten ground-nesting birds and other wildlife on islands.

## What does a brown rat look like?
The brown rat is a robust, heavy-bodied rodent with coarse grey-brown fur, a paler grey or off-white underside, small rounded ears and a blunt nose. Adults typically measure 15-28 cm in head and body length, with a scaly, sparsely haired tail of 10.5-24 cm that is shorter than the head and body combined, a useful feature for telling it apart from the black rat. Most weigh between 140 and 500 g, though exceptional individuals have reached over 800 g. Like all rodents, it has a single pair of continuously growing incisors in each jaw, kept in check by constant gnawing; in total it has 16 teeth, with a wide gap (the diastema) separating the incisors from the grinding molars. Its eyesight is relatively poor, but it has an excellent sense of smell, sensitive whiskers and acute hearing that extends well into the ultrasonic range. These senses, together with its agility, climbing ability and willingness to swim, help the brown rat exploit an enormous variety of habitats.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/rat): Brown Rat — wildlife guide.

## Where do brown rats live and what do they eat?
Brown rats are commensal animals, meaning they live in close association with people. They are found in cities, farms, warehouses, sewers, riverbanks and rubbish tips, and have colonised every continent except Antarctica by stowing away on ships and in cargo. Despite the name 'Norway rat', genetic and historical evidence points to an origin in northern China and Mongolia, from where the species spread along human trade routes, reaching Europe in the 1700s. They are strong burrowers, digging extensive systems of tunnels and chambers near reliable food and water. The brown rat is an opportunistic omnivore that will eat almost anything, including grain, fruit, seeds, insects, eggs, refuse and carrion, though cereals form a large part of its natural diet. This dietary flexibility, combined with a willingness to try new foods cautiously, is a key reason for its remarkable global success. Living so close to people, brown rats can damage stored food and structures and can carry diseases, which is why much of their interaction with humans has historically been as a pest species.

## How intelligent and social are rats?
Brown rats are strikingly intelligent and social, which is part of why they have become such important laboratory animals. In the wild they live in large, hierarchical groups built around family units, communicating through scent, body posture and a range of squeaks and ultrasonic calls. They establish dominance hierarchies, groom one another, and recognise individual group members. Studies have shown rats are capable of problem-solving, learning complex tasks, navigating mazes and even appearing to display empathy-like behaviour towards companions in distress. Young rats engage in play, and researchers have recorded ultrasonic 'chirps' associated with positive experiences such as tickling. This intelligence and sociability is exactly what makes the domesticated brown rat, the 'fancy rat', such a rewarding companion animal: pet rats are typically gentle, curious and quick to bond with the people who care for them. The same traits underpin the laboratory rat's central role in biology and medicine, where Rattus norvegicus has contributed to countless advances in our understanding of behaviour, physiology and disease.

## Are brown rats endangered or a conservation concern?
The brown rat is in no danger of extinction. The IUCN lists it as Least Concern, reflecting an enormous, stable and widespread population that benefits directly from human activity. It is not listed under CITES, as it faces no trade-related threat. If anything, the conservation story runs the other way: in many parts of the world the brown rat is an introduced, invasive species, and on islands in particular it can devastate populations of ground-nesting seabirds, reptiles and native insects that evolved without such predators. Conservation programmes on vulnerable islands sometimes focus on removing introduced rats to allow native wildlife to recover. For the animal itself, the brown rat is a model of adaptability rather than fragility, a reminder that 'conservation status' is about a species' place in an ecosystem as much as its raw numbers. Understanding the difference between a thriving commensal species and the threatened wildlife it can affect is an important part of reading any animal's story honestly.

## WARN work
WARN does not run field projects specifically for brown rats, which are abundant and listed as Least Concern, and in many regions are an introduced species rather than threatened wildlife. This guide is part of WARN's free educational work, helping people understand animals accurately and kindly. The wider threats woven through the rat's story, especially habitat change and the pressure invasive species place on vulnerable native animals, are exactly the kinds of challenges that affect the wildlife WARN does work to protect.

## Donation hook
If you have found this guide useful, supporting WARN's free educational work helps us keep telling honest animal stories and caring for the vulnerable wildlife behind them.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/rat): Brown Rat — wildlife guide.

## Why is the brown rat also called the Norway rat?
The name 'Norway rat' is misleading. The species did not originate in Norway; an early naturalist wrongly assumed it had arrived in Britain on Norwegian ships. Genetic and historical evidence instead points to an origin in northern China and Mongolia, from where the brown rat spread along human trade routes to reach Europe in the 1700s and, eventually, almost the entire world.

## What is the difference between a brown rat and a black rat?
Both are common 'true rats', but they differ in build and habits. The brown rat (Rattus norvegicus) is larger and heavier with a blunt nose, small ears and a tail shorter than its body; it prefers ground level, burrows and sewers. The black rat (Rattus rattus) is slimmer with a pointed nose, larger ears and a tail longer than its body, and is a more agile climber that favours roofs and upper storeys.

## Are pet rats and laboratory rats the same species as wild brown rats?
Yes. Pet 'fancy rats' and laboratory rats are both domesticated forms of the wild brown rat, Rattus norvegicus. Through selective breeding they have become tamer, calmer and more varied in colour and coat than their wild ancestors, but they remain the same species. Their intelligence and sociability make fancy rats popular companion animals and laboratory rats invaluable to medical and behavioural research.

## Are brown rats dangerous to humans?
Healthy wild brown rats generally avoid people and are not aggressive, but living so close to humans they can spread certain diseases through their droppings, urine or parasites, and can contaminate stored food. Historically rats have been associated with serious illnesses. Pet fancy rats, by contrast, are bred to be gentle and pose very little risk when kept responsibly and handled with normal hygiene.

## How fast do brown rats reproduce?
Very quickly, which is central to their success. Females can breed from around five weeks old, gestation lasts only about 21 days, and a single litter can contain up to 14 pups, with around seven being typical. A female can produce several litters a year in good conditions. High reproductive output offsets a very high natural mortality rate, as most wild brown rats live barely a year despite a potential lifespan of up to three years.

## What do brown rats eat?
Brown rats eat Opportunistic omnivore; cereals, fruit, seeds, insects, refuse.

## Where do brown rats live?
Brown rats live in Worldwide; every continent except Antarctica.

## How long do brown rats live?
Brown rats typically live Up to ~3 years; most under 1 year in the wild. Wild and captive figures can differ; use the sources listed on the guide for the underlying studies.

## How big is a brown rat?
A Brown rat is about About 15-28 cm, plus a shorter tail. Conservation status: Least Concern (not CITES-listed).


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/mouse): House Mouse — wildlife guide.

## One-line answer
A house mouse (Mus musculus) is a small grey-brown rodent in the family Muridae, typically 7.5–10 cm long with a long tail and large ears. Native to Asia, it now lives worldwide alongside humans, breeds prolifically, and is the ancestor of pet and laboratory mice.

## Introduction
The house mouse (Mus musculus) is a small rodent in the family Muridae and one of the most abundant and widespread mammals on Earth. Originally native to Asia, it spread across the world by living alongside humans, thriving in homes, farms, warehouses and fields wherever food and shelter are found. Rarely heavier than a £1 coin, it is curious, agile and a prolific breeder, with several litters a year. The species is the wild ancestor of the familiar pet mouse and the laboratory mouse, making it one of the most studied animals in science. The IUCN lists it as Least Concern, reflecting its enormous, stable global population.

## Takeaway
The house mouse is one of the most abundant and widespread mammals on Earth, found wherever humans live.

## Takeaway
It is small and light — usually 7.5–10 cm in body length and just 11–30 g in weight, with a tail roughly as long as its body.

## Takeaway
Mice breed prolifically: females mature at around six weeks and can raise several litters a year.

## Takeaway
Most wild mice live less than a year because of heavy predation, though protected mice can reach two to three years.

## Takeaway
Mus musculus is the wild ancestor of both pet and laboratory mice, making it one of science's most important animals.

## Takeaway
The IUCN classifies the house mouse as Least Concern, with a huge and stable global population; it is not CITES-listed.

## What does a house mouse look like?
A house mouse is a small, slender rodent built for squeezing through tight spaces. The body measures roughly 7.5–10 cm from nose to the base of the tail, with a near-hairless tail of similar length, 5–10 cm. Adults typically weigh between 11 and 30 grams — lighter than a £1 coin. The fur is usually grey-brown above and paler beneath, though colour varies. The most distinctive features are the large, rounded, sparsely furred ears and the prominent dark eyes, which give the mouse keen senses in low light. Long whiskers help it feel its way along walls and through burrows in the dark. The front paws have four clawed digits and the hind paws five, well suited to climbing, gnawing and grooming. Mice see relatively poorly but have an acute sense of smell and hearing, including ultrasonic frequencies humans cannot detect, which they use to communicate. Their continuously growing incisors — a hallmark of all rodents — must be worn down by constant gnawing, which is why mice readily chew through packaging, wood and soft materials.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/mouse): House Mouse — wildlife guide.

## Where do house mice live and what do they eat?
House mice are commensal animals, meaning they live in close association with people. Although the species originated in Asia, it travelled with human trade and settlement to become established on every inhabited continent. Mice colonise houses, barns, granaries, shops and warehouses, but also live independently in fields, hedgerows and grassland, especially in warmer months. They are adaptable nest-builders, shredding paper, fabric and plant material to make snug nests in wall cavities, under floors or in burrows. Mice are largely nocturnal and stay close to shelter, typically foraging within a small home range. They are omnivorous but feed mainly on plant matter — seeds, grains, roots and stems — supplemented by insects and almost any human food they encounter. A mouse needs very little water and can obtain much of its moisture from food, which helps it survive in dry stored-grain environments. This close relationship with people brings the species into frequent conflict with humans over stored food and property, but it is also the reason the house mouse has become so extraordinarily successful and widespread.

## How do house mice breed and how long do they live?
The house mouse is famous for its rapid reproduction. Females reach sexual maturity at around six weeks of age and males at about eight weeks. After a short gestation of roughly 19–21 days, a female gives birth to a litter of 3–14 young, with six to eight being typical. The pups are born blind, hairless and helpless, but develop quickly and are weaned within about three weeks. A single female can produce 5 to 10 litters in a year under good conditions, so populations can grow explosively when food and shelter are plentiful. This high reproductive rate is balanced by heavy losses: in the wild, most mice live less than a year because of intense predation by owls, hawks, foxes, cats, snakes and many other animals, making the house mouse a key link in many food chains. In protected conditions, such as a home cage or laboratory, mice commonly live two to three years. The species' fast life cycle, small size and ease of care are exactly why it became the foundation of the pet mouse and the laboratory mouse.

## Are house mice the same as pet and lab mice?
Yes — pet mice ('fancy mice') and laboratory mice are domesticated strains of the wild house mouse, Mus musculus. Over many generations, selective breeding has produced an enormous variety of coat colours, patterns and temperaments in fancy mice, and highly standardised, genetically defined strains in laboratory animals. The laboratory mouse is one of the most important model organisms in biology and medicine: its short life cycle, small size and close genetic similarity to humans have made it central to research on genetics, immunology, cancer and countless diseases. It is worth distinguishing the house mouse from other small rodents people often confuse it with. Mice are generally smaller and more slender than rats, with proportionally larger ears and thinner tails. They differ too from voles, which have blunter snouts, smaller ears and shorter tails, and from shrews, which are not rodents at all but insect-eaters with long pointed noses. Understanding these differences helps people identify the animals sharing their environment — and appreciate that the unassuming house mouse underpins both a popular pet and a cornerstone of modern science.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/mouse): House Mouse — wildlife guide.

## WARN work
WARN does not run field conservation projects for the house mouse — it is an abundant, Least Concern species that needs no rescue effort, and this guide is part of WARN's free educational work to help people understand the animals around them. The same forces that shape mouse populations, especially habitat change and the loss of natural predators, also affect the wild species WARN does help protect, which is why understanding common animals matters for conservation as a whole.

## Donation hook
If this free guide helped you, a small gift helps WARN keep producing clear, science-based animal education and care for the wildlife that genuinely needs our help.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/mouse): House Mouse — wildlife guide.

## What is the difference between a mouse and a rat?
Mice and rats are both rodents in the family Muridae, but mice are much smaller. A house mouse weighs only 11–30 g with a slender body, large ears and a thin, hair-like tail, while rats are far heavier and bulkier with proportionally smaller ears and thicker tails. Mice also tend to produce smaller droppings. Both can live alongside humans, but they are distinct species.

## How long do house mice live?
In the wild, most house mice live less than a year because of intense predation by owls, foxes, cats, snakes and other predators, as well as harsh weather and food shortages. In protected conditions, such as a home, pet cage or laboratory, where they are safe from predators, house mice commonly live two to three years. Their fast life cycle is balanced by these high natural losses.

## How fast do mice breed?
Very fast. Female house mice can reproduce from around six weeks of age, and after a gestation of just 19–21 days they give birth to litters of 3–14 young, typically six to eight. A single female can raise 5 to 10 litters in a year under good conditions. This high reproductive rate allows mouse numbers to grow rapidly when food and shelter are plentiful.

## What do house mice eat?
House mice are omnivorous but feed mainly on plant matter such as seeds, grains, roots and stems. They will also eat insects and almost any human food they can reach, which is why they are drawn to kitchens, granaries and food stores. Mice need very little water and can get much of their moisture from food, helping them survive in dry environments like stored grain.

## Are pet mice and laboratory mice the same as house mice?
Yes. Both pet 'fancy' mice and laboratory mice are domesticated strains of the wild house mouse, Mus musculus. Generations of selective breeding have produced many coat colours in fancy mice and genetically standardised strains for research. The laboratory mouse is one of the most important model organisms in biology and medicine, used to study genetics, cancer, immunology and many human diseases.

## Are house mice endangered?
No. The house mouse is one of the most abundant and widespread mammals on Earth, found on every inhabited continent wherever humans live. The IUCN Red List classifies it as Least Concern, with a very large and stable global population, and it is not listed under CITES. Far from being threatened, the species is so successful that it is often considered a pest where it shares human food and homes.

## Where do house mouses live?
House Mouses live in Worldwide, alongside humans. A house mouse (Mus musculus) is a small grey-brown rodent in the family Muridae, typically 7.5–10 cm long with a long tail and large ears.

## Are house mouses dangerous?
House Mouses are not generally dangerous to people. A house mouse (Mus musculus) is a small grey-brown rodent in the family Muridae, typically 7.5–10 cm long with a long tail and large ears. Give wild individuals space and do not corner or handle them.

## How big is a house mouse?
A House Mouse is about 7.5–10 cm (plus a 5–10 cm tail). A house mouse (Mus musculus) is a small grey-brown rodent in the family Muridae, typically 7.5–10 cm long with a long tail and large ears. Conservation status: Least Concern.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/iguana): Iguana — wildlife guide.

## One-line answer
An iguana is a large, mostly herbivorous, tree-dwelling lizard of the Americas. The familiar green iguana (Iguana iguana) reaches about 1.7 metres including its long tail, sports a spiny crest and throat dewlap, and is listed as Least Concern, though several other iguana species are endangered.

## Introduction
The iguana most people picture is the green iguana (Iguana iguana), a large, tree-dwelling lizard native to the forests and riverbanks of Central and South America and the Caribbean. Despite its size — up to roughly 1.7 metres from nose to tail-tip — it is a gentle herbivore, browsing leaves, flowers and fruit high in the canopy. Bright green when young, adults can turn greyish, orange or bluish depending on origin and mood. Hardy and striking, green iguanas are popular but demanding pets, and escaped or released animals have formed wild, invasive populations in places like Florida. "Iguana" can also mean dozens of other species, some of them seriously endangered.

## Takeaway
The green iguana (Iguana iguana) is a large, arboreal, mostly herbivorous lizard of Central and South America and the Caribbean.

## Takeaway
It can reach about 1.7 metres including the tail, with a spiny dorsal crest, a throat dewlap and a light-sensing parietal 'third eye'.

## Takeaway
The IUCN lists the green iguana as Least Concern, but it is regulated under CITES Appendix II.

## Takeaway
Released and escaped pets have created invasive populations in Florida, Hawaii and elsewhere.

## Takeaway
Many other iguanas — such as Galapagos and Fijian species — are threatened or endangered.

## Takeaway
Iguanas are popular but demanding pets, needing space, warmth, UVB light and a careful plant-based diet.

## What does an iguana look like and how big does it get?
The green iguana is unmistakable: a long, slender lizard with a crest of soft spines running from the neck down the back, a loose flap of skin under the chin called a dewlap, and a banded, whip-like tail that makes up roughly half its total length. Large adults reach about 1.7 metres from snout to tail-tip, with some exceptional individuals exceeding two metres; males are heavier and more ornate than females, the biggest weighing several kilograms. Colour is variable and a little misleading. Hatchlings and juveniles are bright leaf-green for camouflage, but adults shift towards grey-green, dull orange, brownish or even bluish tones depending on their population, temperature, age and breeding condition. On top of the head sits a pale scale known as the parietal eye, a primitive light-sensing organ that detects changes in brightness and overhead movement — useful for spotting circling predators — though it cannot form images like the true eyes. Large jowls and prominent round scales beside the eardrum are most developed in mature males.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/iguana): Iguana — wildlife guide.

## Where do iguanas live and what do they eat?
Green iguanas are native to a broad sweep of the American tropics, from southern Mexico through Central America and across much of South America to central Brazil, Paraguay and Bolivia, plus many Caribbean islands. They are strongly arboreal, favouring trees along rivers, lakes and mangroves, and are excellent swimmers — when alarmed they often drop from a branch straight into the water below and paddle away with their tails. Adults are almost entirely herbivorous, browsing the leaves, shoots, flowers and fruit of well over a hundred different plants. This leafy diet means they rely on basking in warm sunshine to raise their body temperature enough to digest food, so they spend long stretches motionless in the canopy. Beyond their native range, escaped and deliberately released pets have established free-living, invasive populations in places such as southern Florida, Hawaii, Puerto Rico and parts of Asia, where they can damage gardens, crops and infrastructure and compete with local wildlife.

## Are iguanas good pets, and which iguanas are endangered?
Green iguanas are among the most widely kept pet reptiles, which is exactly why so many end up homeless or released. They are long-lived and can grow surprisingly large, demanding a tall, spacious, warm enclosure, strong UVB lighting, high humidity and a varied, calcium-rich plant diet.

Poor husbandry commonly leads to metabolic bone disease and other health problems, and mature animals — especially males in breeding season — can become powerful and defensive. They are best suited to experienced keepers who can commit for the long term.

It is important to separate the green iguana's secure status from that of its relatives. While Iguana iguana is listed as Least Concern by the IUCN, several other iguanas are in real trouble: the Galapagos land and marine iguanas and the Fijian banded and crested iguanas, for example, are threatened by habitat loss, invasive predators and a changing climate. International trade in iguanas is regulated under CITES Appendix II.

## Explore iguana species on WARN
This hub focuses on the familiar green iguana — but readers often search for Galapagos, Caribbean or Lesser Antillean species. WARN publishes a twelve-species iguana library linked from this page covering green iguana, spiny-tailed relatives, Galapagos land and marine iguanas and more.

Each species page includes range, ecology, CITES status and honest messaging about why most iguanas are poor pets and some are strictly protected.

Released pets drive invasive populations in Florida and beyond — responsible ownership starts with understanding what you are taking on.

## WARN work
WARN does not run field projects specifically for green iguanas — the species is common, listed as Least Concern, and lives largely outside the countries where our partners work. This guide is part of our free educational library, which exists to help people understand and respect wildlife. The threats that endanger rarer iguanas and other reptiles — habitat loss, the wildlife trade and a warming climate — are the same pressures bearing down on the animals our partners do protect on the ground.

## Donation hook
If clear, science-based wildlife guides like this one are useful to you, a small gift helps us keep them free while supporting the animals our partners protect.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/iguana): Iguana — wildlife guide.

## Are iguanas dangerous to humans?
Green iguanas are not venomous and generally prefer to flee, but large adults can defend themselves. They have many small sharp teeth, strong jaws and sharp claws, and can deliver a painful whip with the tail. Bites and scratches can cause injury and may carry Salmonella bacteria. Most problems involve stressed pets or cornered wild animals; given space, iguanas usually avoid confrontation.

## What do iguanas eat?
Adult green iguanas are almost entirely herbivorous, browsing leaves, shoots, flowers and fruit from over a hundred plant species. They do not naturally need animal protein, and a leafy, calcium-rich diet is essential for pets to avoid metabolic bone disease. Because plant food is hard to digest, iguanas bask in the sun to warm up enough for their gut bacteria to break it down.

## How big do iguanas get and how long do they live?
Green iguanas are among the largest lizards in the Americas, reaching about 1.7 metres from snout to tail-tip, with the tail forming roughly half that length; some exceptional animals top two metres. The tail alone makes them look enormous. Well-cared-for captive iguanas can live well over a decade, and sometimes around twenty years, which is part of why they are such a demanding long-term commitment.

## Why are iguanas a problem in Florida?
Green iguanas are not native to Florida. Escaped and released pets have bred into large free-living populations in the warm south of the state, where they dig burrows that undermine pavements and seawalls, strip gardens and crops, and leave droppings in pools and on patios. During rare cold snaps, chilled iguanas can become torpid and fall from trees. They are considered an invasive species there.

## Are iguanas endangered?
It depends on the species. The familiar green iguana (Iguana iguana) is listed as Least Concern by the IUCN and is locally abundant, even invasive in some regions. But several other iguanas are threatened or endangered, including the Galapagos land and marine iguanas and the banded and crested iguanas of Fiji, which face habitat loss, introduced predators and climate change. International iguana trade is regulated under CITES Appendix II.

## What is the spiky flap of skin under an iguana's chin?
That flap is called the dewlap, a fold of skin beneath the throat supported by part of the jaw. Iguanas extend it during displays — to look larger and more impressive to rivals, to court mates, and to warn off threats. It also helps with temperature regulation, since spreading it exposes more surface to absorb or release heat. Males generally have larger, more prominent dewlaps than females.

## Where can I read about individual iguana species?
WARN's iguana wildlife guide links to a twelve-species library covering the green iguana, Galapagos land and marine iguanas, spiny-tailed species and more — each with range, ecology and conservation status.

## Where do green iguanas live?
Green Iguanas live in Central and South America, Caribbean. An iguana is a large, mostly herbivorous, tree-dwelling lizard of the Americas.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/adder): Adder — wildlife guide.

## One-line answer
An adder (Vipera berus) is a small venomous snake of Europe and Asia, identified by a dark zigzag stripe along its back. It is Britain's only venomous snake, hunts small mammals and lizards, and is shy, biting humans only in defence.

## Introduction
The adder (Vipera berus), also called the European viper, is a small venomous snake famous for the bold zigzag stripe running down its back. It is the only venomous snake native to Britain and the only snake found inside the Arctic Circle, ranging from western Europe across Russia to the Pacific coast of Asia. Adders favour heathland, moorland, woodland edges and coastal dunes, where they bask to warm up and hunt small mammals, lizards and amphibians. Though its venom can give a painful, occasionally serious bite, the adder is shy and bites only defensively. Globally it is classed as Least Concern, but in the UK it is declining and legally protected.

## Takeaway
The adder is Britain's only venomous snake and the only snake whose range crosses into the Arctic Circle.

## Takeaway
Its trademark dark zigzag stripe down the back makes it one of the easiest European snakes to identify.

## Takeaway
Adders give birth to live young rather than laying eggs, an adaptation to cool northern climates.

## Takeaway
Bites are rarely dangerous to healthy adults but are painful and always need prompt medical attention.

## Takeaway
Globally the adder is Least Concern, but UK populations are declining and are protected by law.

## Takeaway
Adders are shy and will retreat if given the chance; almost all bites happen when a snake is trodden on or handled.

## What does an adder look like and how do you identify it?
The adder is a stocky, modest-sized snake, usually 60-70 cm long, with the largest individuals — most often females in the north of the range — exceeding 90 cm. Its most reliable feature is the continuous dark zigzag stripe running the length of the back, set against a paler ground colour. Males tend to be grey or whitish with a black zigzag, while females are typically brown or reddish with a darker brown pattern. The head carries a distinctive V- or X-shaped marking, and the eyes have vertical, cat-like pupils with a red or coppery iris. Some adders are entirely black (melanistic), which can make the zigzag hard to see — these are more common in cooler, upland areas where dark skin helps absorb heat. In Britain the adder can be confused with the harmless grass snake and the legless slow worm, but neither has the bold zigzag, and the grass snake instead shows a yellow-and-black collar behind the head. The adder's short, slightly upturned snout and relatively chunky build also help separate it from Britain's slimmer non-venomous reptiles.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/adder): Adder — wildlife guide.

## Where do adders live and what do they eat?
Vipera berus has one of the largest ranges of any terrestrial snake, stretching from Britain and western Europe across Scandinavia, Russia and northern Asia to the Pacific. Remarkably, it lives farther north than any other snake and is the only species found inside the Arctic Circle, thanks to its tolerance of cold. Adders favour habitats with a mix of open basking spots and dense cover: heathland, moorland, bogs, woodland rides, hedgerows, rough grassland and coastal dunes. They are cold-blooded and spend much of the day regulating their temperature, basking in the morning sun before becoming active hunters. The diet is mostly small mammals such as voles, mice and shrews, along with lizards (including common lizards and slow worms), amphibians like frogs and newts, and occasionally nestling birds. Prey is killed with a quick venomous bite, then released and tracked by scent until the venom takes effect. In the cooler parts of their range adders hibernate through winter, often communally in shared underground refuges called hibernacula, emerging in early spring to bask and breed.

## Are adder bites dangerous to humans?
Adder venom is medically significant but, compared with many of the world's vipers, relatively mild. The snake is not aggressive: it relies on camouflage and will almost always slip away if given the chance, biting only when trodden on, cornered or handled. A bite is painful and typically causes swelling, bruising and sometimes nausea, dizziness or a drop in blood pressure; serious systemic reactions are uncommon but possible, especially in children, older people or those with allergies. Fatalities are very rare — in Britain only a small number of deaths have been recorded over more than a century. Even so, every adder bite should be treated as a medical emergency: keep the affected limb still and below heart level, remove rings or tight clothing, and seek hospital care promptly, as antivenom may be given in severe cases. Dogs are bitten more often than people, usually on the face or paws while investigating a basking snake, and also need veterinary attention. The sensible response to meeting an adder is simply to step back and leave it alone — it poses no threat to anyone who keeps their distance.

## How do adders breed and survive cold climates?
The adder's reproduction is closely shaped by its cold northern home. Rather than laying eggs, females are ovoviviparous: the eggs develop inside the body and the young are born live, typically 3 to 20 at a time in late summer or early autumn. This strategy lets the mother carry her developing young to warmer basking sites, giving the embryos enough heat to develop in climates where eggs left in the ground might never hatch. Breeding is demanding, so females in cooler regions often reproduce only once every two or three years, recovering condition in between. In spring, males emerge from hibernation first and perform a 'dance of the adders', a ritualised wrestling contest in which rival males rear up and try to push each other down to win access to females. Adders are long-lived for a small snake, and hibernation is a dangerous period — a significant proportion of juveniles and some adults do not survive the winter. These slow life-history traits, combined with the loss and fragmentation of heath and moorland, help explain why UK adder populations are sensitive to disturbance and slow to recover.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/adder): Adder — wildlife guide.

## WARN work
The World Animal Rescue Network does not run field projects specifically for the adder — its native range lies well outside the countries where WARN's partners work partner countries — so this guide is part of WARN's free educational work to help people understand and respect wildlife. The pressures that threaten adders, above all the loss and fragmentation of habitat, are the same forces that endanger the animals WARN does protect, which is why sharing accurate, calm information about misunderstood species like venomous snakes matters.

## Donation hook
If clear, fear-free wildlife guides like this one are useful to you, a small gift helps WARN keep producing them and supports the animals in our care.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/adder): Adder — wildlife guide.

## Is the adder the only venomous snake in the UK?
Yes. The adder (Vipera berus) is the only venomous snake native to the United Kingdom. Britain's two other native snakes — the grass snake and the smooth snake — are non-venomous, and the legless slow worm is a lizard, not a snake. Adders are shy and bites are rare, but the snake is legally protected and should never be handled or harmed.

## How dangerous is an adder bite?
Adder bites are painful but rarely life-threatening to healthy adults. A bite usually causes swelling, bruising and sometimes nausea or dizziness, and serious reactions are uncommon. Deaths are very rare, with only a handful recorded in Britain in over a century. Even so, every bite needs prompt medical care: keep still, remove tight items and go to hospital, as antivenom may be needed in severe cases.

## What does an adder look like?
An adder is a small, stocky snake, usually 60-70 cm long, with a continuous dark zigzag stripe running down its back and a V- or X-shaped mark on its head. Males are typically grey with a black pattern; females are brown or reddish. The vertical, cat-like pupils and reddish eyes are distinctive. Some adders are entirely black (melanistic), which can hide the zigzag.

## Where do adders live?
Adders have a vast range across Europe and Asia, from Britain through Scandinavia and Russia to the Pacific coast — farther north than any other snake, even reaching inside the Arctic Circle. They favour heathland, moorland, bogs, woodland edges, dunes and rough grassland, where they can both bask in the sun and find dense cover to hide in. In the UK they are now patchily distributed and declining in many areas.

## Do adders lay eggs?
No. Unlike many snakes, adders do not lay eggs. They are ovoviviparous: the eggs develop inside the female and she gives birth to live young, typically 3 to 20 at a time in late summer or early autumn. This adaptation lets the mother keep the developing embryos warm by basking, which is essential for breeding successfully in the cold northern climates the adder inhabits.

## Are adders endangered?
Across their huge global range, adders are classed as Least Concern by the IUCN, most recently assessed in 2021. However, the picture is very different locally: in the UK adder populations are declining and fragmented, largely due to habitat loss and disturbance, and the species is protected by the Wildlife and Countryside Act 1981, which makes it illegal to kill, injure or sell them.

## What does an adder eat?
Adders hunt small mammals such as voles, mice and shrews, along with lizards, amphibians like frogs and newts, and occasionally nestling birds. Prey is killed with a quick venomous bite, then released and tracked by scent until the venom takes effect. They bask on heathland, moorland and woodland edges before becoming active hunters.

## How long do adders live?
Adders are long-lived for a small snake, though this guide does not cite a specific maximum age. Females in cooler regions often reproduce only once every two or three years, and a significant proportion of juveniles fail to survive their first winter hibernation — traits that make UK populations slow to recover from habitat loss.

## How big is an adder?
Most adders are 60–70 cm long, with the largest individuals — usually females in the north of the range — exceeding 90 cm. The species is Britain's only venomous snake, identified by the continuous dark zigzag stripe running down its back and a V- or X-shaped mark on the head.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/toad): Common Toad — wildlife guide.

## One-line answer
A toad is a tail-less amphibian, typified by the common toad (Bufo bufo), with dry, warty skin, short legs and toxin-secreting parotoid glands behind the eyes. Unlike frogs, toads usually walk rather than leap, live mostly on land, and return to ponds each spring to breed.

## Introduction
The common toad (Bufo bufo) is a squat, warty-skinned amphibian found across much of Europe, north-west Africa and western Asia. Unlike the smooth, leaping frog, a toad has dry, knobbly skin and short legs, so it tends to walk or make small hops rather than long leaps. Behind each eye sits a swollen parotoid gland that secretes a defensive toxin, deterring many predators. Toads spend most of the year on land in woods, gardens and hedgerows, hunting slugs, worms and insects at night. Each spring, adults migrate—often hundreds of metres—back to the ponds where they were born to breed.

## Takeaway
Toads and frogs are both amphibians, but toads have dry, warty skin, shorter legs and walk rather than leap.

## Takeaway
Parotoid glands behind the eyes secrete bufotoxin, a defence that makes most predators avoid eating toads.

## Takeaway
Each spring, common toads migrate back to ancestral breeding ponds, often crossing roads in large numbers.

## Takeaway
Females lay eggs in long double strings (not clumps like frogs), wrapped around water plants.

## Takeaway
Globally the common toad is listed as Least Concern by the IUCN, but it is declining in parts of the UK.

## Takeaway
Toads are gardeners' allies, eating large numbers of slugs, snails, beetles and other invertebrates.

## What does a common toad look like?
The common toad is a robust, broad-bodied amphibian with dry, warty skin in shades of olive, brown, grey or dull yellow, helping it blend into leaf litter and soil. It typically reaches 8-13 cm in length, though large females can grow to around 15 cm; males are usually smaller and slimmer. The eyes are striking, with a horizontal pupil and a copper, orange or gold-coloured iris. The most distinctive feature is a pair of large, raised parotoid glands set behind the eyes, which secrete a defensive toxin. Toads have relatively short hind legs compared with frogs, which is why they tend to crawl or make small, awkward hops rather than the long, powerful leaps of a frog. Their skin is rougher and drier to the touch, and they lack the dark 'mask' marking common in frogs. Southern populations are generally larger than northern ones, and females are consistently stockier than males, a difference that becomes obvious in the breeding season.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/toad): Common Toad — wildlife guide.

## How do toads breed and migrate?
Common toads spend most of the year on land, but in early spring they undertake a remarkable mass migration back to the ponds where they themselves hatched, sometimes travelling several hundred metres or more. Many follow the same routes year after year, which is why toads are so often seen crossing roads on mild, damp spring nights. At the pond, smaller males grip larger females in a mating embrace called amplexus, and a male may be carried to the water on a female's back. The female lays a long, paired string of eggs—often 3 to 4.5 metres long and containing roughly 1,500 to 6,000 eggs—winding it around submerged plants. Unlike frogs, toads do not lay rounded clumps of spawn. The eggs hatch into small, dark tadpoles after about ten days. Toad tadpoles are mildly toxic, which helps protect them from fish and other predators, and they gradually develop legs before emerging from the water as tiny toadlets in summer.

## Are toads poisonous, and what do they eat?
Toads are not venomous in the sense of biting or stinging, but they are mildly poisonous to eat. The parotoid glands behind the eyes, along with smaller glands across the skin, secrete bufotoxin—a bitter, irritating substance that can sicken or deter a predator that tries to swallow the toad. This chemical defence means many animals learn to leave toads alone, although hedgehogs, grass snakes, rats, crows and birds of prey can still take them, and some predators skilfully avoid the toxic skin. The toxin can cause drooling, vomiting or worse in pet dogs or cats that mouth a toad, so curious pets are best kept away. As hunters, toads are voracious nocturnal predators of invertebrates, eating slugs, snails, worms, beetles, ants, woodlice, caterpillars, flies and spiders; large individuals occasionally take tiny mice. This appetite for slugs and other garden pests makes the toad a welcome, natural form of pest control.

## WARN work
WARN does not run field projects specifically for the common toad, which lives largely outside the countries where our partners work. This guide is part of our free educational work to help people understand and value wildlife. The threats that affect toads—habitat and pond loss, busy roads cutting across migration routes, pollution and disease—are the same pressures that harm many amphibians and other animals WARN does protect, so learning about one helps protect them all.

## Donation hook
If this guide deepened your appreciation for wildlife, a small gift helps keep WARN's educational work free for everyone.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/toad): Common Toad — wildlife guide.

## What is the difference between a frog and a toad?
Both are amphibians, but the common frog has smooth, moist skin, longer legs and moves in long leaps, while the common toad has dry, warty skin, shorter legs and tends to walk or make small hops. Frogs lay eggs in rounded clumps; toads lay them in long double strings. Toads also have prominent parotoid glands behind the eyes that frogs lack.

## Are toads poisonous to touch or to dogs?
Common toads secrete bufotoxin from glands in their skin, which is irritating and bitter to deter predators. Simply touching a toad is generally harmless, but you should wash your hands afterwards and avoid touching your eyes or mouth. If a dog or cat mouths a toad, the toxin can cause drooling, vomiting and distress, so keep curious pets away and contact a vet if symptoms appear.

## What do toads eat?
Toads are nocturnal hunters that eat a wide range of invertebrates, including slugs, snails, earthworms, beetles, ants, woodlice, caterpillars, flies and spiders. They detect prey mainly by movement and flick out a sticky tongue to catch it. Large toads occasionally take very small mice. Because they consume so many slugs and snails, toads are valued as natural, chemical-free pest controllers in gardens.

## How long do common toads live?
In the wild, common toads are thought to live for about ten to twelve years, which is long-lived for such a small animal. Survival is lowest in the egg and tadpole stages, when many are eaten by fish, birds and insects. Toads in captivity, free from predators and harsh weather, can live far longer, with exceptional individuals recorded at several decades old.

## Why do toads cross roads in spring?
In early spring, common toads migrate from their land habitats back to the ponds where they hatched in order to breed, often following the same routes their ancestors used. Where these traditional routes cross roads, large numbers of toads can be seen travelling on mild, damp nights—and many are killed by traffic. This is why volunteers in some areas help carry toads safely across busy roads during the migration.

## Are common toads endangered?
Globally the common toad is listed as Least Concern by the IUCN because it has a very wide range across Europe, north-west Africa and into Asia. However, it is not doing equally well everywhere: surveys suggest the species has declined in parts of the UK over recent decades, linked to the loss of ponds, habitat fragmentation and busy roads. Protecting ponds and migration routes helps reverse local declines.

## Where do common toads live?
Common Toads live in Europe, NW Africa, western and northern Asia. A toad is a tail-less amphibian, typified by the common toad (Bufo bufo), with dry, warty skin, short legs and toxin-secreting parotoid glands behind the eyes.

## Are common toads dangerous?
Common Toads are not generally dangerous to people. A toad is a tail-less amphibian, typified by the common toad (Bufo bufo), with dry, warty skin, short legs and toxin-secreting parotoid glands behind the eyes. Give wild individuals space and do not corner or handle them.

## How big is a common toad?
A Common Toad is about Typically 8-13 cm; up to ~15 cm. A toad is a tail-less amphibian, typified by the common toad (Bufo bufo), with dry, warty skin, short legs and toxin-secreting parotoid glands behind the eyes. Conservation status: Least Concern (declining in parts of the UK).


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/newt): Newt — wildlife guide.

## One-line answer
A newt is a small semi-aquatic salamander in the subfamily Pleurodelinae. Newts alternate between water and land, breeding in ponds in spring and feeding on insects and other invertebrates. They are famous for regenerating lost limbs and organs, and many produce defensive skin toxins.

## Introduction
Newts are small, semi-aquatic salamanders in the subfamily Pleurodelinae, with more than 100 species found across Europe, Asia, North Africa and North America. They split their lives between water and land: most return to ponds each spring to breed, then spend much of the year hunting on damp ground nearby. Newts are best known for a near-magical talent — the ability to regrow lost limbs, tails and even parts of vital organs. Many also carry skin toxins for defence. In the UK two species are familiar: the common smooth newt and the larger great crested newt, which is strictly protected by law. This guide explains what newts are, how they live and why they matter.

## Takeaway
Newts are salamanders in the subfamily Pleurodelinae, with over 100 species across Europe, Asia, North Africa and North America.

## Takeaway
They are semi-aquatic, breeding in ponds in spring and living on damp land for much of the year.

## Takeaway
Newts can regenerate lost limbs, tails and parts of organs — a rare ability among vertebrates.

## Takeaway
Many species produce skin toxins; the most potent, in some Pacific newts, contain tetrodotoxin.

## Takeaway
The smooth newt is common and Least Concern; the great crested newt is strictly protected in the UK.

## Takeaway
Healthy ponds and connected wetlands are essential, so habitat loss is the chief threat to newt populations.

## What is a newt and how does it differ from a salamander?
A newt is a type of salamander — every newt is a salamander, but not every salamander is a newt. Newts make up the subfamily Pleurodelinae within the salamander family Salamandridae, comprising roughly 100 species in around sixteen genera. They are distinguished mainly by their lifestyle: newts are strongly semi-aquatic, typically returning to water each breeding season, whereas many other salamanders are fully terrestrial or fully aquatic. Newt skin tends to be rougher and less slimy than that of other salamanders, and during the breeding season the males of some species develop showy crests and bright colours. Like all amphibians, newts have permeable skin and lay shell-less eggs, tying them closely to clean, damp habitats. They have lizard-like bodies with four limbs and a long tail, but unlike reptiles they have no scales or claws. Adults of common European species are small, generally around 7 to 16 centimetres long including the tail. This blend of aquatic and terrestrial living, combined with their delicate skin, makes newts useful indicators of the health of ponds and the wider countryside.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/newt): Newt — wildlife guide.

## How do newts live and reproduce?
Most newts follow an annual rhythm tied to water. In spring, adults migrate to ponds to breed; in the Northern Hemisphere the main breeding season falls around late spring and early summer. Males of many species court females with elaborate displays, fanning scent toward them with their tails. Females then lay eggs — sometimes hundreds, with the great crested newt producing roughly 200 to 300 — often carefully folding each egg inside a leaf of pondweed for protection. The young hatch as aquatic larvae with feathery external gills, feeding on tiny invertebrates. After several weeks they undergo metamorphosis and leave the water as juveniles called efts, which spend a year or more on land before maturing. Adults split their time between water and damp terrestrial cover such as log piles, leaf litter and long grass, hunting insects, worms, slugs and other small prey, mostly after dark. In colder regions newts hibernate over winter, sheltering under logs, stones or in burrows. European species such as the smooth newt can live several years in the wild, and great crested newts may reach well over a decade.

## Why can newts regrow body parts?
Newts are among the very few vertebrates that can regenerate complex body parts throughout adult life. If a newt loses a limb or part of its tail — or even damages tissue in its eye, heart or spinal cord — specialised cells near the wound can revert to a flexible, immature state, multiply, and then re-form the missing structure. This process produces a functional replacement rather than mere scar tissue. Such regeneration is exceptional: most adult mammals, including humans, cannot regrow lost limbs at all. Because of this, newts have long been studied by scientists hoping to understand the biology of healing and tissue repair. Their other striking defence is chemical. Many newts secrete toxins through the skin to deter predators, and a few are remarkably potent: some Pacific newts of the genus Taricha contain tetrodotoxin, the same powerful poison found in pufferfish. The rough-skinned newt can carry enough toxin to be dangerous if eaten, and some garter snakes have evolved resistance in a long-running predator-prey arms race. Bright belly colours often warn predators of this hidden toxicity.

## Are newts endangered, and what threatens them?
Newts vary widely in status. Many familiar species are common and listed as Least Concern by the IUCN — the smooth newt, for example, remains widespread across Europe. Others are far rarer, and some have suffered severe declines; the Yunnan lake newt of China has been considered extinct since the 1970s. The great crested newt is assessed globally as Least Concern but is declining in places and is strictly protected in the UK and across the European Union as a European Protected Species. In Britain it is illegal to capture, kill, disturb or trade great crested newts, or to damage their habitat, without a licence — protections that can require careful surveys and mitigation before building work proceeds. The broad threats to newts are the loss and pollution of breeding ponds, the draining of wetlands, the fragmentation of land that newts must cross between water and shelter, and the spread of amphibian diseases. Because newts breathe partly through their skin and depend on clean water, they are sensitive to environmental change, which is one reason their presence is taken as a sign of a healthy landscape.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/newt): Newt — wildlife guide.

## WARN work
WARN does not run dedicated field projects for newts, which live largely outside the countries where our partners work; this guide is part of our free educational work to help people understand and value wildlife. The threats newts face — habitat loss, pollution and the draining of wetlands — are the same pressures that harm the amphibians and other animals WARN does protect, so caring about one helps all.

## Donation hook
If this guide deepened your wonder at the natural world, a small gift helps keep our educational work free and supports the animals in our care.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/newt): Newt — wildlife guide.

## What is the difference between a newt and a salamander?
A newt is a kind of salamander, so all newts are salamanders but not all salamanders are newts. Newts form the subfamily Pleurodelinae and are strongly semi-aquatic, usually returning to water to breed each year. Their skin is typically rougher than that of other salamanders, and breeding males of some species grow showy crests and bright colours.

## Are newts poisonous to humans or pets?
Many newts secrete mild toxins through their skin to deter predators, and a few are highly toxic. Some Pacific newts of the genus Taricha contain tetrodotoxin, a potent poison, and eating one can be dangerous. Most newts are harmless if left alone, but you should never handle them roughly or put them near your mouth, and always wash your hands afterwards.

## Can newts really regrow their limbs?
Yes. Newts are among the few adult vertebrates that can regenerate complex body parts, including lost limbs, tails and parts of organs such as the eye, heart and spinal cord. Cells near the wound revert to a flexible state, multiply and rebuild the missing structure, producing a working replacement rather than just scar tissue. This rare ability makes newts important subjects in medical research.

## Where do newts live?
Newts are found across Europe, Asia, North Africa and North America, with more than 100 species in total. They are semi-aquatic, breeding in ponds, ditches and slow streams in spring, then living on damp land nearby — under logs, leaf litter and stones — for much of the year. Clean water and connected, undisturbed land are both essential to them.

## What do newts eat?
Newts are carnivores. Aquatic larvae feed on tiny water invertebrates, while adults hunt insects, worms, slugs, snails, tadpoles and other small prey, mostly after dark. In ponds they also take aquatic insects, water fleas and frog spawn. Their appetite for slugs and insects makes them welcome visitors to wildlife-friendly gardens with a healthy pond.

## Are newts protected by law in the UK?
The great crested newt is strictly protected in the UK and across the European Union as a European Protected Species. It is illegal to capture, kill, disturb or trade them, or to damage their habitat, without a licence, and their presence can require surveys and mitigation before building work. The smooth and palmate newts receive more limited protection but should also be treated with care.

## Are newts dangerous?
Newts are not generally dangerous to people. A newt is a small semi-aquatic salamander in the subfamily Pleurodelinae. Newts alternate between water and land, breeding in ponds in spring and feeding on insects and other invertebrates. Give wild individuals space and do not corner or handle them.

## How long do newts live?
Newts typically live Aquatic larva, terrestrial eft, adult. A newt is a small semi-aquatic salamander in the subfamily Pleurodelinae. Newts alternate between water and land, breeding in ponds in spring and feeding on insects and other invertebrates. Wild and captive figures can differ; use the sources listed on the guide for the underlying studies.

## How big is a newt?
A Newt is about About 7-16 cm (common European species). A newt is a small semi-aquatic salamander in the subfamily Pleurodelinae. Newts alternate between water and land, breeding in ponds in spring and feeding on insects and other invertebrates.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/slow-worm): Slow Worm — wildlife guide.

## One-line answer
A slow worm (Anguis fragilis) is a legless lizard native to Britain and Europe. Though snake-like, it is a true lizard: it can blink with movable eyelids and shed its tail to escape predators. It lives in gardens and grassland, eating slugs, snails and worms.

## Introduction
The slow worm (Anguis fragilis) is one of nature's great impostors: it looks like a small bronze snake, but it is in fact a legless lizard. Found across Britain and much of Europe, it spends most of its life hidden beneath logs, stones and compost heaps, emerging to hunt slow-moving prey such as slugs, snails and earthworms. Smooth-scaled and secretive, it can live for decades and is a familiar, welcome resident of gardens and allotments. Two features give away its lizard identity: it can blink, because it has eyelids that snakes lack, and it can shed its tail to escape a predator. In the UK it enjoys full legal protection.

## Takeaway
The slow worm is a legless lizard, not a snake or a worm, despite its appearance.

## Takeaway
It can blink and shed its tail, two abilities that betray its lizard identity.

## Takeaway
It feeds largely on slugs, snails and worms, making it a gardener's natural ally.

## Takeaway
Slow worms are remarkably long-lived, often reaching around 30 years in the wild.

## Takeaway
Females give birth to live young rather than laying eggs, usually in late summer.

## Takeaway
In the UK the species is fully protected by law, and it is classed as Least Concern globally.

## Is a slow worm a snake or a lizard?
A slow worm is a lizard, not a snake, despite its limbless, serpentine body. It belongs to the family Anguidae, a group of lizards that have evolved to lose their legs as an adaptation to burrowing and slipping through dense vegetation. Two features reliably distinguish it from any British snake. First, a slow worm has movable eyelids and can blink, whereas snakes have a single fixed, transparent scale over each eye and cannot close them. Second, it can perform caudal autotomy, deliberately shedding part of its tail when seized by a predator; the discarded tail wriggles to distract the attacker while the lizard escapes. The regrown tail is only ever a short, blunt stub, never as long or neat as the original, which is why many adults look slightly truncated. Other clues include a smooth, polished body with non-overlapping scales, a more uniform colour, and a blunt head that is not clearly set off from the neck. Far from being dangerous, the slow worm is harmless, non-venomous and rather shy, spending much of its life hidden underground or beneath cover.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/slow-worm): Slow Worm — wildlife guide.

## What do slow worms eat and where do they live?
Slow worms are slow-moving, ambush-style hunters that specialise in soft, slow prey. Their diet is dominated by invertebrates: small slugs and snails, earthworms, insects and spiders. This appetite for slugs makes them a quiet asset in any garden, allotment or vegetable plot, controlling pests without chemicals. Because they are semi-fossorial, meaning partly burrowing, slow worms spend most of their time out of sight beneath logs, flat stones, leaf litter and especially compost heaps, where decaying material generates gentle warmth and attracts the invertebrates they hunt. Rather than basking openly in the sun as many lizards do, they often warm themselves indirectly by lying beneath sun-heated objects such as sheets of corrugated metal or discarded paving. Their preferred habitats include rough grassland, woodland edges, heathland, hedgerows, railway embankments and humid, undisturbed corners of gardens. A wildlife-friendly garden with a log pile, a compost heap and some unmown grass offers nearly everything a slow worm needs, which is why these reptiles are among the most likely to be encountered by people across much of Britain and Europe.

## How do slow worms reproduce and how long do they live?
Unlike most reptiles that lay eggs, the slow worm is ovoviviparous: the eggs develop and hatch inside the female's body, so she gives birth to live young. After mating in spring, females carry developing embryos through the summer and typically produce a litter of around eight to twelve young between mid-July and August, though litters can range more widely. Each newborn is a slender, golden creature only a few centimetres long, fully independent from birth. Slow worms are extraordinarily long-lived for such a small animal. In the wild they may reach roughly thirty years of age, and one famous captive individual at a European zoo is reported to have survived to around fifty, possibly the greatest age recorded for any lizard. This longevity, combined with low reproductive output, means populations recover slowly from losses. Colour offers a rough guide to sex: males tend to be plainer grey-brown, sometimes flecked with pale blue spots, while females often retain a dark stripe down the spine and darker flanks, echoing the patterning of the gold-and-black juveniles.

## WARN work
World Animal Rescue Network does not run field projects specifically for slow worms, which are widespread and not globally threatened; this guide is part of WARN's free educational work to help people identify and value the wildlife around them. The same pressures that affect slow worms, especially habitat loss, intensive land use and the destruction of undisturbed corners, also threaten many of the animals WARN does protect in its partner countries, so understanding one species helps support them all.

## Donation hook
If this guide helped you see a familiar garden animal in a new light, a small gift helps us keep wildlife education free and support the habitats that animals everywhere depend on.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/slow-worm): Slow Worm — wildlife guide.

## Is a slow worm a snake?
No. A slow worm is a legless lizard, not a snake, even though it has no limbs and looks serpent-like. The clearest difference is that slow worms have movable eyelids and can blink, whereas snakes have fixed, transparent eye scales. Slow worms can also shed their tail to escape predators, an ability snakes do not share. They are harmless and non-venomous.

## Are slow worms dangerous or venomous?
No, slow worms are completely harmless to people and pets. They are non-venomous, do not bite defensively in any meaningful way, and are shy, retiring animals that prefer to hide rather than confront anything larger than their invertebrate prey. In fact they are beneficial in gardens, eating slugs and snails. In the UK it is illegal to deliberately kill, injure or harm them.

## What do slow worms eat?
Slow worms feed mainly on soft-bodied invertebrates, including small slugs, snails, earthworms, insects and spiders. Their fondness for slugs makes them a natural form of pest control and a welcome presence in gardens and allotments. They hunt slowly and deliberately, often beneath logs, stones or in compost heaps where such prey is abundant, rather than chasing fast-moving animals in the open.

## How long do slow worms live?
Slow worms are remarkably long-lived for small reptiles. In the wild they commonly reach around 30 years of age, and a celebrated captive specimen is reported to have lived to roughly 50, possibly the oldest age recorded for any lizard. This long lifespan is paired with slow, modest reproduction, so populations recover only gradually if numbers fall.

## Why is it called a slow worm if it is not a worm?
The name is misleading on both counts: a slow worm is neither slow in the sluggish sense nor a worm. It is a legless lizard. The word 'worm' here derives from older English usage meaning a serpent or reptile, and 'slow' may relate to its unhurried movement. Despite the name, it can move surprisingly quickly when alarmed and slips easily through grass and soil.

## How can I attract or protect slow worms in my garden?
Slow worms thrive in undisturbed, wildlife-friendly gardens. A compost heap, a log or stone pile, and an area of unmown grass provide warmth, cover and a steady supply of slugs and worms. Avoid slug pellets and chemical pesticides, take care when forking compost or strimming long grass, and leave sheltered corners undisturbed. These simple steps make a garden a safe haven for them.

## Where do slow worms live?
Slow worms live in Gardens, grassland, heath, woodland edge, compost heaps. A slow worm (Anguis fragilis) is a legless lizard native to Britain and Europe. Though snake-like, it is a true lizard: it can blink with movable eyelids and shed its tail to escape predators.

## How big is a slow worm?
A Slow worm is about Typically 40-45 cm; up to about 50 cm. A slow worm (Anguis fragilis) is a legless lizard native to Britain and Europe. Though snake-like, it is a true lizard: it can blink with movable eyelids and shed its tail to escape predators. Conservation status: Protected under the Wildlife and Countryside Act 1981.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/grass-snake): Grass Snake — wildlife guide.

## One-line answer
A grass snake is a large, harmless, non-venomous snake of Europe and western Asia (Natrix helvetica and Natrix natrix). It is Britain's largest snake, lives near water, swims well, eats mostly amphibians, and is recognised by a yellow-and-black collar behind the head.

## Introduction
The grass snake is a non-venomous, harmless snake found across much of Europe and into western Asia, and is the largest snake native to Britain. It is usually olive-green, grey or brownish, and most are identified by the yellow-and-black "collar" marking just behind the head. A keen swimmer, it lives close to ponds, ditches, marshes and slow rivers, where it hunts amphibians such as frogs, toads and newts. When cornered it relies on bluff rather than biting: it may hiss, release a foul-smelling musk, or convincingly feign death. In the UK it is a protected species, and like many wetland animals it depends on healthy, connected freshwater habitats.

## Takeaway
The grass snake is non-venomous and harmless to humans — it has no venom and almost never bites.

## Takeaway
It is the UK's largest snake, with mature females reaching well over a metre and occasionally close to 1.5 m.

## Takeaway
Look for the yellow-and-black collar behind the head, plus dark bars or spots along the flanks.

## Takeaway
It is a strong swimmer that hunts amphibians — frogs, toads and newts — usually near ponds and wetlands.

## Takeaway
When threatened it bluffs: hissing, releasing a foul musk, or playing dead with its tongue lolling out.

## Takeaway
Grass snakes are protected in the UK and rely on healthy, well-connected freshwater and rough-grass habitats.

## How do you identify a grass snake?
Grass snakes are typically olive-green, greyish or brownish above, often with rows of small black bars or spots running down each flank. The clearest field mark is the collar just behind the head — usually a band of yellow, cream or orange bordered by black — although it can be faint or, rarely, almost absent in some individuals. The underside is creamy or whitish with bold black, chequerboard-like markings. The pupil is round (not vertical), and the eye looks bright and alert. Adult females are noticeably larger than males; the biggest reach over a metre and can approach 1.5 m, making this Britain's largest snake. In the UK the grass snake is easily told from the adder (Vipera berus), which is shorter, has a vertical pupil and a bold dark zig-zag down its back, and from the legless slow worm, which is a lizard with a glossy, cylindrical body. If you find a snake near water in Britain that swims confidently and lacks a zig-zag, it is almost certainly a grass snake.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/grass-snake): Grass Snake — wildlife guide.

## Where do grass snakes live, and what do they eat?
Grass snakes are strongly associated with water and damp habitats. They favour pond margins, ditches, marshes, wet meadows, canal banks, slow rivers and gardens with ponds, but also use woodland edges, hedgerows, rough grassland and compost heaps. Their range spans much of Europe and extends into western Asia and north-west Africa; the western grass snake (Natrix helvetica) occurs across western Europe including Britain, while the barred grass snake (Natrix natrix) occupies more eastern parts of the range. Amphibians dominate the diet — frogs, toads and newts — and grass snakes are excellent swimmers that will pursue prey into the water. They also take fish, tadpoles and occasionally small mammals or nestlings. Prey is swallowed whole and alive, as the snake has no venom to subdue it. Being cold-blooded, grass snakes are most active in warm weather and bask in sunshine to raise their body temperature, retreating to cover or hibernating underground through the cold months.

## Are grass snakes dangerous, and how do they defend themselves?
Grass snakes are harmless to people. They are non-venomous and very reluctant to bite, relying instead on a memorable repertoire of bluffs to escape predators. A cornered grass snake may flatten its head and hiss loudly, or rear up in a mock-threatening posture. If that fails, it can release a foul-smelling fluid from its cloacal glands — a pungent musk that deters many predators. Most famously, the grass snake may feign death (thanatosis): it rolls onto its back, goes limp, lets its mouth gape and its tongue loll out, and may even emit musk and a little blood, presenting a thoroughly unappetising 'corpse'. Once the threat passes, it rights itself and slips away. Because they are shy and quick to flee, encounters are usually brief. The best response to finding one is simply to watch quietly and let it move on; in the UK it is an offence to deliberately kill, injure or harm them.

## How do grass snakes breed?
Grass snakes are among the few egg-laying (oviparous) snakes in their northern range, which shapes how they reproduce. Mating takes place in spring after emergence from hibernation. In summer the female lays a clutch — commonly around eight to forty eggs, sometimes more — in a warm, moist site where decomposition generates heat, such as compost heaps, manure piles, rotting vegetation or leaf litter. This warmth incubates the eggs, since the climate alone is often too cool. Several females may use the same favoured site, occasionally producing large communal egg masses. The young hatch in late summer or early autumn as miniature replicas of the adults, complete with the collar marking, and are independent from the start. Grass snakes can be long-lived for a small reptile, and warm compost heaps in gardens can be valuable breeding sites — one reason gardeners are encouraged to leave undisturbed heaps and log piles where these snakes may be present.

## WARN work
WARN does not run field projects specifically for the grass snake — it is widespread and classed as Least Concern, and most of its range lies outside the countries where WARN's partners work partner countries. This guide is part of WARN's free educational work, helping people recognise and value a misunderstood, harmless animal. The threats grass snakes face — loss and drainage of wetlands, fragmented habitats and the persecution of snakes through fear — are the same pressures of habitat loss and human conflict that affect the animals WARN does protect.

## Donation hook
If this guide helped you see snakes a little more kindly, a small gift helps us keep producing free, science-based wildlife education and care for the animals in our partner countries.


World Animal Rescue Network (https://worldanimalrescuenetwork.org/wildlife-guides/grass-snake): Grass Snake — wildlife guide.

## Is a grass snake venomous or dangerous?
No. The grass snake is completely non-venomous and harmless to humans. It has no venom glands and is extremely reluctant to bite, preferring to flee or bluff. When threatened it may hiss, release a foul musk or play dead rather than attack. It poses no danger to people or pets, and the best thing to do on meeting one is to watch quietly and let it move on.

## How big do grass snakes get?
Grass snakes are the UK's largest snake. Adults are commonly around 70–100 cm long, but mature females grow considerably larger than males and the biggest can exceed a metre, occasionally approaching about 1.5 m. Males are slimmer and shorter. Despite the impressive length they are slender, lightweight snakes, and their size is one way to tell them from the shorter, stockier adder.

## What do grass snakes eat?
Grass snakes feed mainly on amphibians — frogs, toads and newts — which is why they live close to ponds and wetlands. They are strong swimmers and will chase prey into the water. They also eat fish, tadpoles and, less often, small mammals or nestlings. Because they have no venom, they swallow prey whole and alive, relying on their flexible jaws to engulf animals wider than their own heads.

## Why do grass snakes play dead?
Playing dead, or thanatosis, is a defence against predators. A cornered grass snake rolls onto its back, goes limp, gapes its mouth and lets its tongue hang out, sometimes releasing foul musk and a little blood. Many predators prefer live prey or are put off by the smell, so a convincing 'corpse' encourages them to lose interest. Once the danger has passed, the snake rights itself and escapes.

## How can I tell a grass snake from an adder?
In the UK the easiest clues are the markings and head. A grass snake is usually olive or green with a yellow-and-black collar behind the head, a round pupil and no zig-zag. An adder is shorter and stockier, has a vertical, cat-like pupil, and a bold dark zig-zag stripe down its back. Adders are venomous; grass snakes are not. A snake seen swimming confidently near water is almost always a grass snake.

## Where do grass snakes lay their eggs?
Grass snakes are egg-layers, and the female seeks out warm, moist places where rotting material generates heat to incubate the clutch — compost heaps, manure piles, leaf litter and rotting vegetation are all favoured. She typically lays from around eight to forty or more eggs in summer, and several females may use the same warm site. The young hatch in late summer or autumn. Undisturbed garden compost heaps can be valuable breeding sites.

## Where do grass snakes live?
Grass Snakes live in Ponds, marshes, ditches, wet grassland, gardens. A grass snake is a large, harmless, non-venomous snake of Europe and western Asia (Natrix helvetica and Natrix natrix).

## How long do grass snakes live?
A precise wild lifespan for grass snakes is not firmly established in the sources cited on this guide. A grass snake is a large, harmless, non-venomous snake of Europe and western Asia (Natrix helvetica and Natrix natrix). Where longevity figures appear in the literature they vary by region, sex and whether animals are wild or captive.