European Water Vole

European Water Vole
Conservation status
Least Concern (IUCN 3.1)[2]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Cricetidae[1]
Subfamily:	Arvicolinae
Genus:	Arvicola
Species:	A. amphibius[1]
Binomial name
Arvicola amphibius (Linnaeus, 1758)
Synonyms
Arvicola terrestris

The European Water Vole or Northern Water Vole, Arvicola amphibius (formerly A. terrestris), is a semi-aquatic rodent. It is often informally called the Water Rat or Ratty, although it only superficially resembles a true rat.^[3] Water voles have rounder noses than rats, deep brown fur, chubby faces and short fuzzy ears; unlike rats their tails, paws and ears are covered with hair.

In the wild, they survive for 2 years on average; most do not survive a second winter. In captivity, they normally start to deteriorate in condition as they approach their third year, becoming thinner and losing much of their fur; they nearly all die during their third winter.

The water vole is legally protected in the United Kingdom.

Appearance

Water voles reach 140–220 millimetres (5.5–8.7 in) in length plus a tail of 55–70 millimetres (2.2–2.8 in) of this. Adults weigh from 160–350 grams (5.6–12.3 oz), juveniles weigh less but must reach around 140–170 grams (4.9–6.0 oz) to be able to survive their first winter.

Taxonomy

The binomial applied to the Water Vole is Arvicola amphibius, it was formerly known by the junior synonym A. terrestris. The confusion stems from the fact that Linnaeus described two species of Water Vole on the same page of the same work. Those two forms are now universally considered the same species. It has been recognized as A. amphibius (Linnaeus, 1758) because the first source to unite the two forms that Linnaeus had treated separately into a single species chose A. amphibius as the valid name.^[1] The species is widely known by the synonym A. terrestris which for many decades was treated as the valid name.

Some authorities consider the Southwestern Water Vole (Arvicola sapidus) to be the same species, but this is now generally considered to be distinct.^[2][4]

Range

The water vole Arvicola amphibius is found in much of Great Britain, northern and central Europe and in parts of Russia.^[2]

Habitat

Water vole, Ore Mountains, Germany

In Britain, water voles live in burrows excavated within the banks of rivers, ditches, ponds, and streams. Burrows are normally located adjacent to slow moving, calm water which they seem to prefer. They also live in reed beds where they will weave ball shaped nests above ground if no suitable banks exist in which to burrow.

Water voles prefer lush riparian vegetation which provides important cover to conceal animals when they are above ground adjacent to the water body. Areas of heavily grazed and trampled riparian habitats are generally avoided.^[5] Water voles may be displaced by the introduction of riparian woodland and scrub as they prefer more open wetland habitats away from tree cover.

As well as frequenting typical lowland wetland habitats dominated by rank marginal aquatic vegetation, water voles are also just as at home in areas upland 'peatland' vegetation where they utilise suitable small ditches, rivers and lochs surrounded by moorland up to 1000 m asl (e.g. northern Scotland).^[6]

In Europe and Russia, they may venture into woods, fields, and gardens. They live under the snow during the winter.

Diet

Water voles mainly eat grass and plants near the water. At times, they will also consume fruits, bulbs, twigs, buds, and roots. In Europe, when there is enough food to last water voles a long time, water vole "plagues" can take place. Water voles eat ravenously, destroying entire fields of grass and leaving the fields full of burrows, during these plagues. Ecologists have discovered that normally vegetarian water voles living in Wiltshire, England have started eating frogs' legs and discarding the bodies. It has been speculated that this is to make up for a protein deficiency in the voles' diet.^[7]

Food remains alone are not a reliable indicator of the presence of this species, as other smaller voles can also leave remains of large grasses and rushes.^[8]

Breeding

The mating period lasts from March into late autumn. The female vole's pregnancy lasts for approximately 21 days. Up to 8 baby voles can be born, each weighing around 10 grams (0.4 oz). The young voles open their eyes three days after their birth. They are half the size of a full grown water vole by the time they are weaned.

Behaviour

Water voles are expert swimmers and divers. They do not usually live in large groups. Adult water voles each have their own territories, which they mark with faecal latrines located either near the nest, burrow and favoured water's edge platforms where voles leave or enter the water.^[6] Latrines are known to be a good survey indicator of this species, and can be used to gauge abundance of animals.^[9] They also scent-mark by using a secretion from their bodies (a flank gland), although this is not normally detectable during a field survey. They may attack if their territory is invaded by another water vole.

Conservation

The water vole population in the UK has fallen from its estimated pre-1960 level of around 8 million to 2.3 million in 1990 and to 354,000 (other source: 750,000) in 1998. This represents a 90-95% loss. It is still declining dramatically, the most recent estimate for 2004 is around 220,000. This decline is partly attributed to the American Mink, an aggressive predator of the vole, together with unsympathetic farming and watercourse management which destroyed parts of the water vole's habitat.

On 26 February 2008, the UK Government announced full legal protection for water voles would be introduced from 6 April 2008.^[10]

Consequently, the water vole is the UK's fastest declining mammal and efforts are under way to protect the water vole and its habitat from further destruction. One aspect of water vole conservation in the UK is focussed on non-linear habitats such as reed bed which support extensive networks or metapopulations. Other areas supporting healthy populations of water voles are large conurbations such as Birmingham and London and some upland areas where American Mink are scarce. Across the UK the Wildlife Trusts and other organisations are undertaking many practical projects to conserve and restore water vole populations.

Water voles have recently returned to Lindow Common nature reserve in Cheshire, UK, after many years of absence.^[11] The reserve rangers credit this to conservation management, which included thinning of woodland.

There are also indications that the water vole is increasing in numbers in UK areas where the European otter has made a return.^[12] The otter predates on the American Mink.

Literary apperances

A water vole named Ratty is a leading character in the 1908 children's book Wind in the Willows by Kenneth Grahame: the locality used in the book is believed to be Moor Copse in Berkshire, England, and the character's name "Ratty" has become widely associated with the species and their riverbank habitat, as well as the misconception that they are a species of rat.^[13][14]

In the comic novel and film Cold Comfort Farm by Stella Gibbons, one of the characters, Urk, refers to the subject of his unrequited love, Elfine Starkadder, as his little water vole. Throughout the story, Urk spends a lot of time talking to the water voles on the farm.

References

1. ^ ^{a b c} Musser, Guy G.; Carleton, Michael D. (16 November 2005). "Superfamily Muroidea (pp. 894-1531)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=13000176. 
2. ^ ^{a b c} Amori (1996). Arvicola terrestris. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006.
3. ^ Freeston, Helen (1997). "Tales of the Riverbank—How to spot 'Ratty' (previously "Water Volewatch 97")". Lincolnshire Wildlife Trust. Archived from the original on September 25, 2006. http://web.archive.org/web/20060925091301/http://www.lincstrust.org.uk/conservation/wvole/ratty.php. Retrieved 2006-08-23. 
4. ^ Amori (1996). Arvicola sapidus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 23 August 2006.
5. ^ Strachan, R. and Moorhouse, T. (2006). Water Vole Conservation Handbook (2nd edition). Wildlife Conservation Research Unit, University of Oxford.
6. ^ ^{a b} Harris, S. and Yalden, D.W. (2008). Mammals of the British Isles: Handbook, 4th Edition. The Mammal Society.
7. ^ "Water voles get a taste for frogs". BBC News. 30 April 2010. http://news.bbc.co.uk/1/hi/england/wiltshire/8654410.stm. 
8. ^ Ryland, K. and Kemp, B (2009). "Using field signs to identify water voles - are we getting it wrong?", In Practice, Bulletin of the Institute of Ecology and Environmental Management. 63, March 2009 (pp. 23-25).
9. ^ Strachan, R. and Moorhouse, T. (2006). Water Vole Conservation Handbook (2nd edition). Wildlife Conservation Research Unit, University of Oxford.
10. ^ "Press release on Government news network". 26 February 2008. http://www.gnn.gov.uk/Content/Detail.asp?ReleaseID=355365&NewsAreaID=2)). 
11. ^ "News from Lindow". http://www.macclesfield.gov.uk/standardpage.asp?pageid=10564. Retrieved 2006-08-23. 
12. ^ "Otters 'prompt vole resurgence'". BBC. 2006-09-10. http://news.bbc.co.uk/1/hi/uk/5331740.stm. Retrieved 2006-09-11. 
13. ^ RSPB
14. ^ BBC Devon

External links

• General information on Water Voles