Water Vole Surveying

Back in January, I agreed to carry out a water vole survey as part of the People's Trust for Endangered Species National Water Vole Monitoring Programme. They are carrying out surveys across the country in May each year and calling on volunteers to survey selected sites. The site I chose from their list was a 500 metre stretch of Bishop Wilton Beck, a small stream that crosses the fields between my village and the next one. It had been surveyed before and water voles were found, so I was optimistic about finding them again.

 In the 1990s water vole numbers crashed by 90%

In April, I attended a water vole and otter survey training day, run by Yorkshire Wildlife Trust at Alkborough Flats. We had a talk about water vole and otter ecology and survey methods, followed by a walk around the flats - a huge area of reedbed. It was a good site for the training day, as we found evidence of water voles and otters, as well as lots of badger footprints and latrines.

Stuffed water vole

Water vole latrine

Water vole feeding site

Next, I went to the farm that my survey stretch belongs to and asked the farmer for permission to carry out the survey on his land. I was worried he'd set the dog on me, but in fact the dog was rather elderly and docile, as was the farmer - he was very friendly and supportive. He reckoned they had water voles, an otter, possibly mink and a good population of brown hares on the farm. I asked about the hares, as I've seen very few in the area this year.

I carried out a recce and realised that my survey stretch was rather too shallow and overgrown with tall hawthorn trees, which may once have been a hedge. It's far from ideal habitat for water voles. Walking along the stream itself was like being in woodland, with wild garlic and ivy along the banks. Finding anything here was going to be difficult.

The survey had to be carried out in May, so at the start of the month I put out water vole rafts every 100 metres. Water voles will use these as latrine sites and the number that are used give an indication of the territories occupied, and therefore a reasonable estimate of the population can be worked out. I also set up a camera trap on a small gravel beach, and baited it with apple - water voles love apples!

 Water vole raft in the stream

On May 6th, I got my waders on and walked the length of the survey stretch, in the stream as much as possible, though in many places there was overgrowing vegetation that I had to circumvent. I soon found droppings, but they were too large for water voles and smelt dreadful, so they must be those of a brown rat. There were also holes in the bank, but again they looked more like rat holes than water vole burrows.

Rat dropping

Rat holes

I checked the rafts every week, but none were ever used. The camera trap recorded blackbirds eating the apple I'd put out and took a fuzzy picture of the rear end of a small mammal, most probably a rat. I've had to conclude that water voles are not present on my survey stretch. Negative results are, of course, just as important as the positive ones, but positive ones are more fun.

 Brown rat or water vole?

Further downstream it gets deeper and is more open, so looks to be much better habitat for water voles. I've walked part of this stretch, but have found no positive signs of their presence so far, though under a bridge in Wilberfoss I found an otter spraint.

Otter spraint in Wilberfoss



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