Rodents | Rodentia

Families in this order

• Gundis | Ctenodactylidae1 speciesSmall stocky rodents of bare rocky desert, with a flattened body and short legs with which they push deep into narrow clefts; the ears are small and lie flat against the head, so that nothing is left to catch or tear. On the two inner toes of each hind foot stands a row of stiff horny bristles — the comb that gives the family its name — with which the animal combs the fine sand out of its silky coat; left in, that sand destroys the fur's insulating power. They do not drink: all their water comes from leaves, seeds and buds gathered in the early morning and late afternoon, and the kidneys hold on to the rest. The morning is spent basking flat on a stone. Alarm is passed on with a high whistle and the colony vanishes at once. The litter is small and the young are born furred and open-eyed.
• Old World porcupines | Hystricidae2 speciesThe largest rodents in Europe, and the only ones armoured with quills. Those quills are modified hairs of solid keratin, up to thirty centimetres long over the rump, loosely rooted and never thrown: the animal turns and backs into its attacker so that they pull free and stay behind. On the tail stand short quills open at the tip which give a dry rattle when shaken; together with stamping, hissing and the raising of the crest along the back, that makes a warning which works at a distance. The body is heavy, the gait that of a sole-walker with blunt digging claws, and the food is roots, tubers, bulbs and bark, supplemented with gnawed bones for their mineral. They are strictly nocturnal and spend the day in a burrow system, dug or taken over. The litter is small; the young are born with soft quills that harden within a day.
• Dormice | Gliridae6 speciesSmall squirrel-like rodents with large eyes, rounded ears, long whiskers and — alone among Europe's rodent families — a furred tail, bushy in most species, short and softly haired in the hazel dormouse. The soles carry pads and the claws are slightly curved: all the species climb, and most come to the ground only rarely. The cheekteeth are low-crowned with transverse ridges, suited to buds, fruit, nuts and insects. There is no caecum, which sets the family apart from every other European rodent and means that coarse leaf and grass cannot be digested. They hibernate in earnest: on late-summer fat the body temperature and breathing sink far down, and the fat dormouse may sleep more than half the year. For rodents of this size they live remarkably long. The nest is a woven ball in a tree hole, a nest box or dense scrub.
• Squirrels and marmots | Sciuridae21 speciesOne body plan, used three ways in Europe. The tree squirrels have a long densely furred tail that serves as balance beam, rudder in a leap and blanket in sleep, sharp curved claws, and an ankle joint that can turn the hind foot through half a circle, so that they come down a trunk head first. The ground squirrels and marmots are stockier and shorter-tailed and dig with heavy forelimbs; they live in colonies, warn one another with sharp whistles and hibernate deeply on autumn fat. The flying squirrel stretches a furred fold of skin between wrist and ankle, held out by a cartilage rod at the wrist, and glides on it from tree to tree, steering with the flattened tail. Cheek pouches serve the chipmunks and susliks to carry seed. The whole family is active by day — unusual among rodents.
• Beavers | Castoridae2 speciesThe heaviest rodent on the continent, and wholly fitted out for water. The tail is broad, flattened and covered with horny scales: a rudder in swimming, a prop when gnawing upright, a store of fat for the winter and, slapped down on the surface, an alarm for the whole family. The hind feet are large and webbed; one hind toe carries a split nail with which the fur is combed and kept waterproof with oil and castoreum. The underfur is extraordinarily dense and holds the skin dry. The incisors carry iron-bearing orange enamel on the front; the lips close behind them, so that wood can be gnawed under water without choking. They fell trees for bark and twigs, build dams and lodges, and dig canals to float the timber in. A monogamous pair keeps the previous year's young with it; the kits swim almost at once.
• Jerboas | Dipodidae4 speciesDesert rodents that travel on two legs. The hind legs are three to four times the length of the front pair, and in most species the middle metatarsals are fused into a single strong bone; beneath the toes stand brushes of stiff hair that grip loose sand and keep the foot from sinking. The tail is longer than the body and ends in a tuft: it balances the leap and props the animal up when it stands still. The eyes are large and the hearing chambers greatly enlarged, so that the faint sound of an approaching fox or owl is caught at a distance; escape is a series of long bounds in unpredictably changing directions. They do not drink, taking their water from seeds, roots and insects. By day the animal sits in a burrow whose entrance it plugs with sand from within; in cold or dry spells it sleeps there for long stretches.
• Birch mice | Sminthidae6 speciesSmall mouse-like rodents with a tail one and a half to two times the length of the body, wrapped round grass stems in climbing — half prehensile, and more a fifth limb than a balancing rod. In most species a narrow dark line runs down the back, sometimes with paler stripes beside it; the coat is otherwise an unremarkable yellowish brown. The feet are small and the toes long, fit for working up through the herb layer to seeds, berries and insects, on which the animals pass the summer. Hibernation is extraordinarily long for their size: in the north a birch mouse spends more than eight months in a chamber it has dug underground, and on cool summer nights it falls into torpor as well. There is one litter a year, and few young in it — slow breeding for so small a rodent.
• Voles and hamsters | Cricetidae40 speciesTwo body plans under one roof. The voles and lemmings have a blunt muzzle, small eyes, ears sunk in the fur and a short tail; their cheekteeth consist of prisms of enamel meeting in a zigzag, rootless in most species and growing throughout life — which is what makes a diet of grass, with its load of silica, possible. They dig shallow runs and follow fixed paths through the vegetation, where clipped stems and green droppings give them away. The hamsters are larger, with roomy cheek pouches in which food is carried to a burrow with separate store, nest and latrine chambers, and they sleep through the winter in alternating spells. What marks the family is numbers: vole and lemming populations swell several-fold over a few years and then collapse, and the predators that live on them rise and fall with them.
• Mice and rats | Muridae34 speciesSlender rodents with a pointed muzzle, large eyes and ears, and a long scaly, thinly haired tail that keeps the balance and sheds heat. The cheekteeth carry three rows of cusps side by side, suited to seed as much as to insects, and in most species the menu is broad and opportunistic; that is what has carried the house mouse and both rats to every place where people live. The hind feet are long and the animals jump well; the harvest mouse climbs the stems with a prehensile tail and weaves a spherical nest among them. A large part of the family within this area is desert-dwelling: gerbils and jirds with long hind legs, furred soles and a tufted tail, which do not drink, plug their burrows by day and live on stores of seed. In the spiny mice the back fur is hardened into stiff spines, the skin tears away when the animal is seized, and the young are born furred and open-eyed.
• Blind mole-rats | Spalacidae16 speciesRodents that spend their whole lives underground and are built for it in every part. The body is cylindrical with no perceptible neck, there are no external ears, and the eyes are reduced to a minute remnant under skin grown shut, of use at most for measuring day length. There is no external tail either. Digging is done not with the feet but with the strongly forward-jutting incisors, which work outside the closed lips, and with the broad, flat-fronted head driven through the soil like a wedge; a fringe of stiff bristles along the snout sweeps the loose earth aside, and the short powerful legs push it back. They do not come to the surface: the spoil is forced up into mounds. They live on roots, tubers and bulbs stored in chambers, each animal alone and fierce about its own system, and they make themselves understood by drumming the head against the tunnel roof.
• Spiny rats and coypu | Echimyidae1 speciesA South American family whose members are mostly rat-like forest animals with spiny guard hairs, and one of which has ended up in Europe: the coypu, a heavy semi-aquatic rodent that escaped from fur farms and has settled in marshes, ditches and river banks. The hind feet are large, with webbing between four of the five toes; the tail is round and scaly, not flattened as in the beaver, and works as a rudder. Eyes, ears and nostrils sit high on the head, so that a swimming animal barely breaks the surface; the lips close behind the heavy orange incisors, so that rootstocks and reed can be gnawed under water. The teats lie high on the flanks, letting the young suckle while the mother swims. There are several litters a year and the young are born furred and open-eyed.
• Cavies and maras | Caviidae1 speciesStocky South American rodents with a large head, a very short tail or none at all, and four toes on the forefoot against three behind, ending in hoof-like nails. The food is grass and herbs, broken down by bacteria behind the stomach in a capacious caecum; the soft pellets this produces are taken up again. Gestation is long for a rodent and the young are born far advanced: furred, seeing, and able to eat solid food within a day. The mara is the long-legged member of the family, built like a hare, with a galloping and bounding gait over open plains; pairs stay together for life and the young are reared in a communal creche to which several pairs come to suckle their own. Europe holds one small population escaped from captivity.