Hamsters Voles Types, distribution and abundance

Public Health Significance of Urban Pests 427 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 426 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