Water voles () inhabit the Paleartic region, spanning most of central and western Europe, Siberia, Mongolia and some parts of southwest Asia (Nowak, 1991).
Water voles live in the banks of rivers, streams, ponds, and other bodies of water that maintain a fairly constant water level. They prefer areas with good vegetation cover. They are mainly found in lowland areas near waterways but also sometimes occur in gardens and fields. Water voles dig lengthy burrows, ranging from 34 m in the winter up to 74 m in the summer. Burrows contain one or two nests and in the winter contain storage chambers for food (Niethammer, 1989; Nowak, 1991). (Niethammer, 1990)
- Aquatic Biomes
- rivers and streams
Average male body length is 210 mm, with females averaging 187 mm. Tail length averages 124 mm in males and 116.5 in females. Males average 263 g, while females average 232 g (Thompson, 1964).
With a dense coat of fur, small, rounded ears, and short tail,resembles other voles of similar size. Water voles are relatively large voles. Their pelage is thick and extends from the head to the end of the tail. Coloration ranges from light to dark brown on top (sometimes black); and from white to slate gray on their underside. This coloration makes them difficult to see in the dense vegetation they prefer. Claws on each of the feet are well developed, and flank glands on the sides of the body used to mark territory are visible most of the time as well. Water voles possess the typical rodent dental formula and posses continuously growing cheek teeth (Niethammer, 1990; Nowak, 1991).
- Range mass
- 70 to 250 g
- 2.47 to 8.81 oz
- Range length
- 120 to 220 mm
- 4.72 to 8.66 in
Male home ranges overlap those of several females and males continually compete for access to receptive females. Research using microsatellite analysis of genetic patterns confirmed that the mating system was promiscuous (Stewart et. al., 1999).
- Key Reproductive Features
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- Breeding interval
- Water voles can have up to 4 litters in each breeding season.
- Breeding season
- Breeding occurs from April to October.
- Range number of offspring
- 2 to 8
- Average number of offspring
- Range gestation period
- 20 to 22 days
- Average weaning age
- 21 days
- Range age at sexual or reproductive maturity (female)
- 5 (low) weeks
- Range age at sexual or reproductive maturity (male)
- 5 (low) weeks
While males sometimes participate in the raising of the young, the females are the main care givers (Niethammer, 1990). The young are born helpless but rapidly develop and become independent.
Water voles are short-lived, probably suffering the highest mortality rates in their first year. They can live up to 5 years in captivity but average lifespan is less than a year in the wild.
- Average lifespan
- 5.4 months
- Average lifespan
- Range lifespan
- 5 (high) years
- Range lifespan
While sometimes living in close proximity to large numbers of other individuals, water voles tend to live in smaller family units, usually comprised of several individuals. Usually present in these family units is the adult generation and up to two generations of young (Niethammer, 1990; Nowak, 1991).
Water voles are mainly active during the day or during dusk and dawn. In addition, water voles tend to limit the extent of their activity to a set range. Some accounts list the maximum "home range" as being 200 square yards, while other experiments have shown the range to extend up to 300 square yards or more from the burrow (Thompson, 1964).
Territories are delimited by scent marking using the flank glands. In marking the territory, these voles wipe the flank glands with their feet, and then proceed to stamp the ground (Niethammer, 1990).
Other behaviors of water voles include the building of latrines for defecation. There is also some reason to believe that latrines serve a dual purpose during mating season of helping to mark territory (Woodroffe, 1990).
Communication and Perception
The diet ofis comprised mainly of various forms of vegetation. This includes different types of grasses, herbs, and sometimes fruits and seeds. Water voles also feed on the roots of some plants, causing extensive root damage and sometimes destruction of crops. In addition to vegetation, water voles will sometimes supplement their diet with water snails, freshwater mussels, and mollusks (Cobet, 1966; Thompson, 1964).
In the winter, water voles usually maintain at least one chamber in the burrow as a place to store grasses and other food to feed on during lean winter months. They do not live entirely off this store, and will still forage for food during the winter (Nowak, 1991).
Common foods eaten include: reed grass, reeds, flote-grass, water snails, freshwater mussels, grasses, sedges, rushes, mollusks, dandelions, cattail, soft grass, moor grass, water milfoil, water crowfoot, herbs, twigs, buds, bulbs, fallen fruit (Thompson, 1964; Niethammer, 1990; Nowak, 1991).
- Animal Foods
- Plant Foods
- seeds, grains, and nuts
- Foraging Behavior
- stores or caches food
Water voles seek safety in their burrows and restrict their movements mainly to areas of dense vegetative cover to avoid predation. Their prodigious reproductive rates generally help to maintain viable populations under predation stress by natural predators. However, non-native American mink (Neovison vison) are decimating water vole populations in the British Isles.
- Anti-predator Adaptations
Water voles are an important prey base for many small to medium-sized predators. They are also important in nutrient cycling through their burrowing and grazing activities in the ecosystems in which they live.
Economic Importance for Humans: Positive
Although their economic benefit is somewhat limited, in some regions (such as that once occupied by the former Soviet Union), water voles are hunted for fur. (Niethammer, 1990)
- Positive Impacts
- body parts are source of valuable material
Economic Importance for Humans: Negative
Negative economic impacts fromon humans stems mainly from the destruction of human crops such as beans, peas, and some forms of apple trees (Niethammer, 1990). In rare circumstances they have also been known to weaken river banks due to their extensive burrowing (Thompson, 1964)
In addition to crop damage and bank damage,is also known to sometimes carry and transmit tularemia. The disease affects mostly wild rodents and rabbits, but can be transmitted to humans by contact with animal flesh or tick bites (Nowak, 1991; WebMD, 1999).
- Negative Impacts
- crop pest
Some humans have attempted to take actions against water voles in efforts to minimize damage to crops (Neithammer, 1990). However, water voles are on the decline in some regions. For example, in England changes due to habitat and introduction of American mink, Neovison vison, is thought to be playing a large role in the decline of water vole populations (Storey, 2001). Conservation efforts are underway in various parts of the British Isles to protect water vole populations.
One interesting piece of information is that water voles (sometimes also known as "water rats") are thought to be the inspiration for the character of "Ratty" in the British novel "The Wind in the Willows" by Kenneth Grahame (Mammal Society, 2001).
Matthew Oliphant (author), University of Northern Iowa, Jim Demastes (editor), University of Northern Iowa.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
living in landscapes dominated by human agriculture.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
active at dawn and dusk
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- female parental care
parental care is carried out by females
an animal that mainly eats leaves.
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- male parental care
parental care is carried out by males
marshes are wetland areas often dominated by grasses and reeds.
having the capacity to move from one place to another.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- seasonal breeding
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
- stores or caches food
places a food item in a special place to be eaten later. Also called "hoarding"
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- young precocial
young are relatively well-developed when born
Jan 2001. "The Mammal Society: Mammal Fact Sheets" (On-line). Accessed 4 Dec 2001 at http://www.abdn.ac.uk/mammal/watervol.htm.
1999. "WebMD - Tularemia" (On-line). Accessed 25 Nov 2001 at http://my.webmd.com/content/asset/adam_disease_tularemia.
Bazhan, N., E. Makarova, T. Yakovleva. 1996. Deprivation of Food During Pregnancy and Reproduction in the Water Vole (*Arvicola terrestris*). Journal of Mammalogy, 77: 1078-1084.
G. B., C. 1966. The Terrestrial Mammals of Western Europe. Philadelphia: Dufour Editions.
Niethammer, J. 1990. Water Voles (Genus *Arvicola*). Pp. 242245 in S Parker, ed. Grzimek's Encyclopedia of Mammals, Volume III. NY: McGraw-Hill Publishing Company.
Nowak, R. 1991. Walker's Mammals of the World, 6th Edition. MD: The Johns Hopkins University Press.
Stewart, W., J. Dallas, S. Piertney, F. Marshall, S. Telfer. 1999. Metapopulation genetic structure in the water vole, Arvicola terrestris, in NE Scotland. Biological Journal of the Linnean Society, 68: 159-171.
Storey, G. 2001. "Environment Agency - Water voles" (On-line). Accessed 4 Dec 2001 at http://www.environment-agency.gov.uk/yourenv/eff/wildlife/mammals/watervoles/?lang=_e®ion=&projectstatus=&theme=&subject=&searchfor=water+vole&topic=&area=&month=.
Thompson, H. 1964. Water Vole (Water Rat) *Arvicola amphibius* L.. Pp. 286-289 in H Southern, ed. The Handbook of British Mammals. Oxford: Blackwell Scientific Publications.
Woodroffe, G., J. Lawton. 1990. Patterns in the production of latrines by water voles (*Arvicola terrestris*) and their use as indices of abundance in population surveys. Journal of Zoology, 220: 439-445.