European Water Vole (Arvicola amphibius or A. terrestris) of Pauline's Swamp

August 3rd 2017 a water vole was spotted at the pond in Pauline's Swamp. I did not have a camera at the time but later that day I donned wellingtons and entered the pond edge to look for, and find, characteristic signs.

The signs to look for are a latrine where the vole defecates characteristic shaped faeces, plants bitten off at a characteristic 45 degree angle and characteristic footprints. The edge of the water is hard, not capable of taking footprints but the other signs are definite identification.

So there was definitely a water vole in Pauline's Swamp - it is impossible to know if there was just one, or more. Water voles generally live in loose colonies, within which each vole is rather territorial. The pond is very small to support such a colony!

In retrospect, the vole explains the first photo of the great spearwort, taken May 27th 2017.

How do water voles travel?

In 2016, Burwell Brook had a flourishing colony of Water Voles. There must have been several females. A female can have 2 or 3 litters a year of about 5 babies. If there were 3 females that is at least 30 babies. The babies when they leave the nest travel or 2 Km mostly along waterways and ditches, to find a new home. In the season when it is wet enough, Pauline's swamp drains into Burwell Brook - distance along the ditches is less than a kilometer. But we cannot know how many made this trip.

What do water voles eat?

Water voles are largely herbivorous and have been known to eat over 200 plant species including sedges, rushes and grasses. In winter they will also eat bark, roots, bulbs and rhizomes. Occasionally they, especially breeding females, will eat frogs, tadpoles, fish, snails and crayfish.

The feeding signs in Pauline's Swamp include a single Great Spearwort stem that was cut, a water plantain that has many leaves and shoots chomped and several water lily flower buds that had been cut off and partially eaten.

Crayfish have been caught in the pond. Hopefully, as there is a lot of suitable vegetation for the voles to eat, as well as lots of tadpoles, frogs and snails, the crayfish are safe.

General biology

They are most active by day. They live for about 5 months in the wild but have been known to live for over 2 years in captivity. Few wild voles live for two years.

Breeding season is March to October during which time 2 or 3, sometimes as many as many as 5, litters of 4-6, sometimes up to 8, offspring will be reared. Pregnancy lasts about 21 days and the young are ready to leave the nest after a similar time. Young voles will travel 1-2 kilometres along water courses in search of suitable habitat, but once they have found a suitable place to live they don't move far from their burrows.

They live in loose colonies but in the breeding season they are territorial. The males defend a length of bank typically 100m, the females about half of that.

Diary

August 13th 2017. The channel through the Chara appears to be diminishing, so we suspect the vole has moved on. Donning my wellingtons once again, I could find no sign that the previous latrine is still in use and there appears to be no new latrine. Furthermore the water plantain, which seems to be a preferred food, is now growing healthy looking new flower spikes. So it appears the water vole has moved on - or it has been predated. Evidence of the vole's presence was first found May 27th 2017 so it has been here about 11 weeks, maybe more.

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Document URI: http://nathist.torrens.org/Aqua/Animals/watervoleps.html
Page first published Thursday the 3rd of August, 2017
Last modified: Wed, 15 Nov 2017 08:53:44 GMT
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