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have come into increasing conflicts with people. Beaver ponds do, however, provide consi- derable benefits to wildlife and fish populations. They also help retain water in stream
drainages and recharge groundwater reservoirs.
13.2.6. Hamsters
The common hamster Cricetus cricetus is found in the grassy steppes and field edges of eastern Europe, including Austria, Belarus, Bulgaria, the Czech Republic, Hungary,
Poland, the former Yugoslavia and the Russian Federation. Pockets of these animals also exist in Belgium, north-eastern France, western Germany, the Netherlands and
Switzerland. During periods of peak population densities, hamsters sometimes emigrate, often appearing in gardens and around houses, as has been recorded in the Czech
Republic, Germany, Hungary and the Netherlands Nechay, 2000. In the eastern part of their range, common hamsters often live in close proximity to people Poljakov, 1968.
Gray hamsters Cricetulus migratorius, which occur on cultivated grasslands and are com- mon in gardens, range eastward from Greece, Bulgaria and Romania towards Asia.
Other European hamster species include Eversmann’s hamster Allocricetulus eversmanni, the Dobrudja hamster Mesocricetus newtoni, the Turkish hamster Mesocricetus brandti
and the Daghestan hamster Mesocricetus raddei. The level of contact between these spe- cies and people depends on hamster population densities, land use patterns, and ecologi-
cal and people-related factors. Their primary food sources are plant materials, including cereal grains, fruits, roots and leaves, although insects are eaten occasionally. Hamsters
hoard sizeable quantities of seeds and other foodstuffs and can be significant agricultu- ral pests. Females produce 2–3 litters a year, with each litter consisting of 2–3 young.
13.2.7. Voles
Voles are among the northern temperate region’s most abundant rodents Elton, 1942. Bank voles Clethrionomys glareolus are common in the deciduous woodland regions of
Europe, occurring as far north as the Arctic Circle and as far south as the Pyrenees and Alps, with a few relict populations present in Italy. Bank voles require ground cover and
are found most frequently in hedgerows, banks, field edges, woodlands and other well- vegetated areas, although in the northern reaches of Europe they can be found on relati-
vely open ground, and in Norway they have been reported to enter homes. Bank voles rarely travel more than about 50m and largely confine their activities to runways built just
under the ground or in ground-hugging vegetation. Bank voles feed primarily on vege- tation, including plant stems, leaves, roots, bulbs, fruits and seeds, although insects make
up about a third of their diet. They are often considered pests, because of their habit of stripping bark from small trees, especially larch, elder and young conifers. Bank vole
populations often fluctuate dramatically over cycles of 3–4-year duration, sometimes becoming serious pests at high densities. Although most voles die within a year after being
born, their high reproductive rates easily compensate for their low survivability. Voles can breed from April to October, producing 4–5 litters a year, each of which contains 3–6
pups. Another species of Clethrionomys, the southern red-backed vole Clethrionomys gap- peri
, can be found in mesic coniferous, deciduous and mixed forests in the mountains of the western United States and thoughout most of Canada.
Non-commensal rodents and lagomorphs
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part. Occasionally, escaped pet Siberian chipmunks have succeeded in establishing more or less permanent populations in Austria, Finland, France, Germany, Italy and the
Netherlands Amori Gipoliti, 1995; Chapuis, 2005. The 22 species of North American chipmunks occur primarily in the mountain forests and nearby sagebrush habitats of the
western third of the continent. A single species, the eastern chipmunk Tamias striatus, occurs abundantly in the deciduous forest regions of the eastern United States and south-
eastern Canada, routinely entering yards and gardens in many suburban areas Mahan O’Connell, 2005. Although chipmunks spend the bulk of their time on the ground,
the eastern chipmunk sometimes nests in hollows in trees, as do a few western species. Species that nest on the ground make a network of shallow burrows under stones or logs.
Some western species occasionally invade homes, where they often build nests in attics or wall spaces, sometimes damaging these structures in the process. Invaded spaces are often
partially filled with large stockpiles of nuts, pine cones and other edible items. Although chipmunk nesting and hoarding activities can cause some damage, they are of little eco-
nomic importance. Their primary foods are fruits, nuts, berries, seeds and occasional invertebrates. Depending on conditions, females can produce two litters a year, with the
first appearing in February to April and the second typically appearing in June to August; each litter usually consists of 2–8 pups.
13.2.5. Beavers
Beavers are large aquatic rodents that exist in both North America and the Eurasian continent. T he European beaver Castor fiber is confined to isolated pockets in
Scandinavia, eastern Germany and certain other sites where it has been recently intro- duced or re-established Veron, 1992. Its preferred habitats are broad river valleys with
extensive floodplains. The Canadian North American beaver Castor canadensis was introduced from North America to Finland, Poland and the Russian Federation, and
now is distributed widely in other parts of Europe. It readily occupies artificial ponds and ditches that provide suitable food and shelter.
Beavers typically build a conical lodge of branches with an underwater entrance and above-water chambers within the lodge. The outside of the lodge is covered with a layer
of mud. Beavers that live in small streams construct extensive stick dams that result in the formation of a small pond. When heavily hunted, beavers may live in burrows in banks
or construct less conspicuous lodges. Beavers eat shrubs, bulrushes, tree buds and roots of aquatic and semi-aquatic plants. In winter, they consume considerable quantities of
bark. Beavers do not become sexually mature until they are 3–4 years of age, and mating occurs from January to March, with 2–4 pups being born sometime between April and
July. Beaver lodges can contain up to three generations from the same family, although the previous season’s offspring are often driven away by the parents to make room for
the current season’s litter.
Originally decimated by the fur trade Banfield, 1974, the Canadian beaver is making a strong comeback in much of North America, as a result of attempts to re-establish for-
mer populations, natural population growth and reduced demand for beaver fur. Due either to their timber-cutting or dam-building activities, recovering beaver populations
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range water voles seem to prefer pastures over more typical riparian habitats. Due to pre- dation by introduced American mink Mustela vison, loss of suitable riverside habitat
and water pollution, water vole populations in the United Kingdom have declined by as much as 90 over the past 25 years. These animals eat various grasses, sedges and other
plants found growing near the edge of their aquatic homes. Water voles also consume cereal grains and fruits, including apples. Breeding takes place from April to October,
with females producing 3–4 litters of 2–7 young per litter. Few water voles live more than a year. If these animals are numerous, their burrowing activities can damage dikes
and canals.
Muskrats Ondatra zibethicus are basically large aquatic voles that are native to North America, but they have been transplanted to many regions in Europe. They are quite
abundant throughout much of North America and occur frequently in ponds and water- ways in suburban and largely urban areas. Muskrats require aquatic habitats with suita-
ble aquatic vegetation for food and shelter. They are valued for their fur, and their tun- nelling activities can cause damage to dikes and stream banks Danell, 1977; Corbet, 1978.
13.2.8. Old World mice
