Invasive American mink My plan this morning was to conduct the bird survey in three large fields, Tinkers, Telegraph and Warner’s Corner – these three make up a block of land that we survey six times during the spring/summer. I got up nice and early, but found a message from the Mink Police that one of the traps had been activated a little earlier, at 05:10.

We’ve been running mink traps in the Bourn Brook all through the autumn and winter, without a single mink, so I was expecting to find something else like one of the water voles. (Water vole that have been leaving their evidence close to the mink raft recently). Therefore I decided to get to the trap straight away in case it was a vole that needed releasing. However, it turned out to be the first mink for a long time – the last ones were caught 12 months ago! Chances are, this is a wandering individual that has been searching for a female without success.

This is the first one I’ve trapped since we linked up with Prof. Bill Amos at Cambridge University. He’s going to analyse DNA from the mink to see if we can find where it might have come from. If it has genes from another local mink, or from a distant mink, it might help us learn more about the population structure and how many more mink we might expect to catch. Once it was dispatched, I took a small sample for DNA extraction, once the labs are open again!

KingfisherA little bit later than planned I made a start on the bird survey at 7:30am. (There were still plenty of birds on the Bourn Brook that would be potential prey for a mink, so I am fairly sure he had only just turned up). I logged a couple of moorhens, several mallards and two kingfishers.

BlackcapThe bushes along the brook were alive with small warblers, many no doubt just arriving or passing through on their migrations and taking advantage of the insect-rich habitat. They were still made up of the two earliest to arrive species – chiffchaff and blackcap. One of the chiffchaff pairs were already nest-lining (carrying feathers into the herbage somewhere) so they have been around for a few days.

This survey area has a lot more mature hedges and areas of scrub and developing woodland, so there are some species of birds here that we don’t see so much on the other areas of Lark Rise Farm, particularly bullfinches (two pairs today), willow warblers (two singing) and song thrushes (about half a dozen territories). There are also a couple of areas of open agricultural buildings which attract swallows, and three were seen today, perhaps enough to make a summer? It certainly felt warm enough. There were more people walking around than I’ve seen on any of my recent surveys, with 19 people logged during the three hours. Fortunately everyone was very well behaved and showing good social distancing!

Grass snake As the morning started warming up, plenty of bees and butterflies started to come out and about, but also my favourite sighting of the morning, a grass snake was warming itself up in a patch of cut scrub that we created during the recent winter. We had made a large habitat pile with some hawthorn that was taking over an area of woodland. The pile was intended for nesting birds and maybe hedgehogs to use, but it was also perfect for this snake as the sun could filter through the branches to a resting place where it could warm up in a safe place – they are vulnerable while cold as they cannot escape predators quickly until their muscles have been warmed up by the sun. Once up to temperature, it would be off into the nearby meadows looking for small mammals, frogs and so on. My first mink and snake of the year!

Dr Vince Lea
Head of Wildlife Monitoring 

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