Saturday, 2 August 2014


In spite of the photos above, I've been concerned this last week that there has been a drop in water vole numbers at one particular site, and in fact I've had three days where I've seen nothing at all. I haven't spotted any sign of mink but there is quite a lot of stoat scat about, and I've had a couple of trail cam clips. So as soon as this rain stops, I'll go back out and have a really good look to try and work out what's going on. Stoats are native predators, therefore they shouldn't be a problem, but I suppose if there's been a big enough explosion in the population this year then that might have reduced water vole numbers severely.


WendyB said...

That does sound worrying...

Still concerned here in Cambridge too - it's only ever a small colony, but I'm now lucky if I get one brief water vole sighting a week - and always in the same part of the ditch, nowhere else along its 500m length. In May I was seeing several different individuals in at least 3 territories, including juveniles, maybe 4 or 5 times a week.

I did see a grass snake a couple of days ago! It shot out from nearly under my feet, then didn't exactly swim, but "skimmed" across the duckweed, to the far bank - the moorhens weren't happy. Someone further along had seen another, larger grass snake in the same area a few weeks ago.

Another predator I guess? The college cat is also under suspicion. Plus a juvenile pike. And a heron. Also disturbance from drunken rowdies in the adjacent park (they sometimes create a real kerfuffle trying, not always successfully, to retrieve footballs from the ditch).

The latest batch of 8 ducklings soon disappeared - but, the moorhens are doing OK, so... (I even wonder if the chicks' over-sized feet are offputting to snakes, pike etc?)

Kate said...

There are natural fluxes throughout the spring/summer/autumn - late May is a breeding peak and you'd expect to see a lot of voles around then and June. Similarly, juveniles tend to disperse and seek new territories in September, so numbers appear to drop. But normally here there are a lot of voles about now, so I don't know what's up.

The grass snake must have been a lovely sight. Snake and pike and heron will all take voles, but again they're native and shouldn't clear out a colony. Footballs aren't much of a problem either: the voles will just hide till the shouting stops. Cats can be, though. Can you ask the college about fitting this one with a flashing collar? They really do help cut down kills, as does keeping the cat in at night, and both actions are better for the cat too.

All we can do is keep watching. I have seen crashes before, and mostly they recover the next year. or, as I say, it may just be a natural flux.

WendyB said...

Thanks yes - I'd also wondered about suggesting a bell on a collar, too. It depends whose cat it actually is - I will investigate - and ask if it's been catching voles (terrible thought..)

There were certainly a lot more voles here last July and August.

The snake was amazing - there are some astonishing photos online of them swallowing frogs..

Kate said...

I gather vole populations are four-yearly cyclic. They have boom years and bust years. In fact, I think archaeologists have sometimes used vole remains to date artefacts, on that premise.