Searching for field signs
As with many mammals, it is not always possible to see water voles, even if they are present. Therefore, the best way of looking for them is to keep an eye out for signs they have left behind.
These include their droppings (usually left in piles called latrines), feeding stations and burrows in the bankside (or, in certain habitats, nests).
Latrines, feeding stations and actual sightings of the animals are all accurate ways of telling us that water voles are living in the area. Burrows can persist for a number of years however, so cannot be used as evidence of current occupation.
The number of feeding signs (each pile of chopped vegetation counts as one), latrines (trampled and untrampled), burrows/nests and sightings in each 100m length of your transect should be counted and recorded on the record form and the grid reference/GPS location of the first and last latrine in each 100m length should also be noted.
Working out the GPS location of field signs: this can either be calculated using a handheld GPS device or most smart phones will have an app you can download to calculate this (such as the OS Locate app or Gridpoint GB app). If you don’t have a GPS handheld device or a GPS app on your phone, then you can mark the location of the field sign on your map and then once you have access to the internet you can go to www.gridreferencefinder.com Once there, zoom in on your site and then right click over the location of the field sign – you will then be told the grid reference/longitude and latitude figures for that location and can record this information on the record form.
- + Latrines
- Latrines are the most distinctive field sign left by water voles
- Droppings are cylindrical with blunt ends, usually 12mm long and 4-5mm wide, resembling a large ‘tic tac’
- Colour varies depending on the diet, from greenish through to dark purple/black
- Can be found individually but usually deposited in discrete latrines
- Latrines are used to mark out territories between February and November
- As the droppings themselves are odourless, voles will often rub their hind feet on scent glands they have on their sides and then stamp on the droppings, resulting in some latrines looking trampled or If a latrine is at least partially trampled, please record as trampled
- Trampled latrines are a good indication that breeding is taking place
To see similar/confusion droppings please refer to Your guide to looking for signs of water voles and other riverbank species.
- + Feeding signs
- Water voles often bring food items to favoured feeding stations along their pathways or on platforms along the water’s edge
- Neat piles of chewed lengths of vegetation are left after feeding
- Sections are typically 8cm long and have 45 degree cuts to their ends
- Commonly eaten plants include coarse grasses, reeds, sedges and rushes
To see similar/confusion field signs please refer to Your guide to looking for signs of water voles and other riverbank species.
- + Burrows
- Water vole burrows appear as a series of holes along the water’s edge, some just above or at the water level on steep banks, others can be below the water level
- There can also be burrows occurring further up the bank, up to 3m from the water’s edge.
- The holes are typically wider than they are high with a diameter of 4-8cm.
To see similar/confusion burrows please refer to Your guide to looking for signs of water voles and other riverbank species.
- + American mink
American mink are a medium-sized member of the weasel family. They are non-native and are a predator of water voles.- They are generally dark brown, with a distinctive white patch on the bottom of the chin
- Mink mark their territories using distinctive scats. Mink scat has an unpleasant rancid odour and usually contains mammal hair or feathers.
- Mink tracks usually follow the soft edge of a water body and are easy to spot.
- They have five toes which radiate from a crescent-shaped central pad which can be clearly seen in soft mud, while on harder surfaces often only four toes imprints are left. A large male may leave prints up to 35mm long and 35mm wide, whereas the footprints of females and juveniles usually measure 28mm long by 25mm wide.
Mink rafts
- Mink rafts are used to both detect the presence and absence of mink on waterways and control their numbers.
- They were designed by the Game and Wildlife Conservation Trust (GWCT)
- + Otter
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Otters are around the size of a fox but with much shorter legs and a brown back and creamy coloured chest and belly.- Otter spraints can usually be found on prominent objects e.g. on top of fallen logs, on stones in the river or on the bank, on tree roots. Spraints have a musty fishy smell – often likened to jasmine tea! – and usually contain fish bones and scales.
- Otter tracks are larger than those of mink – about the size of those of a spaniel-sized dog, though they often show five claws (whereas dogs only have four).
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As part of the survey we would also like you to record mink and otter signs so we can gain an insight into the distribution of these two species at the survey sites.
Download a printable version of these guidelines and your guide to looking for signs of water voles and other riverbank species:
Next: Carrying out your survey
Training menu:
• An introduction to the NWVMP
• Planning your survey
• Searching for field signs
• Carrying out your survey
• After your survey
• More training links
Feedback – we would really value your feedback on these training pages and also on the monitoring programme. Please email any comments to watervoles@ptes.org.