Tracking ratty: Week 6 of the Water Vole Displacement Project

Compared to the hectic days of strimming week, this week has been rather uneventful. Our main aim has been to track each collared water vole 15 times over the week, taking a GPS reading each time and doing our best to determine whether they are still alive. This then allows us to determine their post vegetation removal home ranges.

A close up encounter with one of our collared voles. Photo credit to Emily Haddy

Working out whether a water vole is still alive is surprisingly difficult. Most voles can be found at different locations throughout the tracking day and so can reasonably be classified as alive. Fear of providing inaccurate data has lead to wild speculations such as “What if a stoat has taken this vole, eaten it, then carried the collar to another location to entertain its stoat children?” but we are assured that this is unlikely.

The location of the burrow of vole number 972 in the vegetation removal zone.

However, there are some voles who seem to be able to sit in the same spot underground for days on end. Of course our data only provides snapshots of a day in the life of a vole; we cannot track the voles throughout every hour of the day, so this is not entirely unexpected but does lead to some confusion. One vole, frequency number 972, had been found in the same location each time we tracked him, after trapping and collaring him, 2 weeks before strimming week. This particular vole elected to stay put DURING the vegetation removal above his burrow too. Charlotte had a good look for the collar, finally despairing and pronouncing number 972 likely to be dead underground (or at least to have left his collar there), much to our disappointment. Needless to say, this vole has now been found away from his burrow several times post strimming, presumably having to cut his super long naps short in order to forage further away from his burrow in the strimmed section of bank.

Misty morning on the Oxfordshire river banks. Photo credit to Emily Haddy

In short, we are learning more about these little creatures every day, and can conclude that, like any good human student, these voles could nap for days.

Having established the home ranges post strimming for each vole this week, we will now spend 3 weeks monitoring their locations and mortality before re-trapping begins. Each location will be logged in GIS, building up a map of the home ranges before and after vegetation removal.

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