Tag Archives: Gatwick Airport

In search of harvest mice again… and again… and again

For my British Animal Challenge I am trying to see every species of mammal, reptile and amphibian living in the wild. For some that’s been fairly straightforward – a case of going to the right place at the right time. Others have been more elusive. My focus this month has been on two of the trickier subjects: harvest mice and water shrews (more on the latter in my next post).

Harvest mice live up to their scientific name: micromys minutus. They are tiny. As their common name suggests, they like living among crops (grains) or areas of tall, seedbearing grasses. This makes spotting them while out and about unlikely.

Harvest mouse on seedhead

Helping out with some scientific harvest mouse trapping projects was likely to be my best chance to see them. So last autumn I volunteered to help with harvest mouse surveying at Gatwick airport. While it was a fascinating experience, we didn’t find any harvest mice. Undeterred, I volunteered for a session this year at Gatwick (work has been pretty intense lately, so I could only get to one).

Once again I got to drive through 10ft high gates topped with barbed wire, past the intimidating signs saying authorised vehicles only, before leaving the car in the glow of the runway lights, and heading off into the mini wilderness just a few hundred metres from the runway, by the River Mole. I was helping out Gatwick’s resident ecologist, Rachel Bicker (they do a surprising amount of biodiversity work at the airport). Like last year, we didn’t find any harvest mice, although we did have a good crop of voles, shrews and woodmice.

Surrey Mammal Group (working with Surrey Wildlife Trust) have been busy on a new harvest mouse project this autumn. They’re working with geneticists to see if hair samples from harvest mice can tell us about connectivity across the landscape. How related are populations in different sites to each other? Are they isolated by habitat fragmentation, or are they able to disperse and mix? This is important for the resilience of the population. And if harvest mice can move between sites, other animals will be able to as well.

Of course, to test this we first need to get samples from harvest mice. Last year the mammal group did a lot of work surveying various sites for harvest mice, and, while they were at it, tested 3 different trap designs. Based on these findings, they selected the sites with the most harvest mice last year to resurvey this year to get the samples, starting with the most harvest mousey site.

Frustratingly, work commitments meant I couldn’t get along to any of the checks at the first site, and I was ill for the week of the second site. I was restricted to seeing the updates on Facebook. The weeks progressed with plenty of voles and shrews (including my nemesis, the water shrew), but not a single harvest mouse. The dedicated volunteers consoled themselves by collecting mouse, vole and shrew poo for students to analyse for parasites.

I was finally able to help for the last check on the third site. Once again, it was the same story, the harvest mice from last year seemed to have disappeared, leaving only voles, woodmice, shrews. It was an interesting and pleasant way to spend the Friday evening, after a stressful week at work, but did leave me wondering what’s happened to the Surrey harvest mouse population.

The next site I volunteered at was by the River Wey, where I used to walk during my student days. I’d never thought about the wildlife that might live in that meadow, but looking at it now, it seems like ideal habitat for small mammals. The news from Facebook was encouraging – the group had finally caught some harvest mice, and got enough samples to analyse the population at that site, at least. Was it the night I would finally see a harvest mouse in the wild?

Harvest mouse site by the River Wey
Harvest mouse site by the River Wey

There are two moments of suspense in checking the Longworth traps. Firstly looking to see if it’s been triggered, and then, once you’ve opened the trap in a bag, waiting to see what will emerge.

Checking a longworth trap
Checking a longworth trap

We hit gold with the first triggered trap we found that evening: a harvest mouse. They are tiny. And lovely. This particular mouse had already been caught, fur clipped and sampled earlier in the week, so we didn’t need to weigh or take a sample from him again.

A not very good photo of the harvest mouse we found
A not very good photo of the harvest mouse we found

In total we had 10 small mammals in traps that night, but only one harvest mouse. Still, I had finally done it: I had seen one of Britain’s smallest and cutest mammals in the wild for the first time.

The surveys are continuing for another week or two, and hopefully we will get enough samples from other sites to compare. It will be interesting to hear the results from the lab. And hopefully it will help us find out more about habitat connectivity in Surrey. If this approach works it may help other parts of the country monitor their living landscape.


Top posts from 2014

As the year draws to a close, it’s a good chance to look back over what’s happened. I’ve been going through the stats to see which posts have had the most views (per month) in 2014. Here are the top 10:

10) 10 more Christmas present ideas for wildlife enthusiasts: It seems lots of people are looking for inspiration for Christmas presents. I just hope Dr C is among them!

9) Looking for harvest mice at an airport: my (ultimately unsuccessful) attempts to see micromys minutus in the unusual setting of Gatwick Airport.

8) Fascinating wildlife fact #11: sharks don’t have bones: a short but interesting glimpse into the anatomy of sharks.

7) On the trail of wild beavers: an account of an expedition to find traces of the first beavers living wild in the UK for hundred of years, and the campaign to keep them that way.

6) Hope for the River Otter beavers: An update on the saga of whether the beavers who were discovered living wild on the River Otter will be allowed to stay free, or rehomed to a zoo. No doubt there will be more posts about this topic next year, as there’s still no definite plans.

5) Kingfishers: Another post from the River Otter (3 in the top 10!). This time it’s some of my better attempts at photographing kingfishers. Still room for improvement, but I’m getting better at it!

4) How to tell who’s been nibbling your nuts: This post outlines how to tell the difference between a nut nibbled by a squirrel, woodmouse, bank vole or dormouse. It contains close up photos to help with identification.

3) Dormouse license! I’ve finally received my dormouse license. This post reflects on what this means, and  the journey to get this far…

2) 5 more recent posts that have made me think: This post links to 5 posts by other bloggers that have made me think. It includes reintroduction of large carnivores in the UK, the hunting act, hedgehogs, flooding, and Christian’s relationship with nature.

1) Plan to cull badger cubs shows the cull’s not about bovine TB: Like the River Otter beavers, the badger cull has been a saga with many twists and turns. This post discusses the recent announcement that the timing of the culls next year will be moved forward to when cubs are first emerging from the sets.


Looking for harvest mice at an airport

6.10am on a chilly November morning. It will be almost another hour before the sun rises, and a mist clings to the ground in the pre-dawn gloom. Most sensible people are still in bed, but I’m at Gatwick Airport. Not catching a flight to somewhere warm, nor waiting to welcome a loved one home. I’m here to see some wildlife.

An airport seems an unlikely place to see any exciting animals. Acres of tarmac, deafening noise, light and air pollution. I was intrigued, which is partly what brought me there so early in the morning. That and the hope of seeing a harvest mouse.

Beyond the public areas of the airport there are some pockets rich in wildlife. They have Bechsteins bats, the rare long-horned bee and great crested newts. But it was harvest mice I was interested in.

Chilly morning at Gatwick airportThe previous night Jim Jones from Surrey Wildlife Trust and Rachel Bicker, an ecologist at Gatwick, had set out 60 small mammal traps, and we were here to see what had been caught.

Jim showed us how to check the traps, and if occupied, how to weigh and sex the animal, then reset the trap with fresh bait. Our first occupant was a male field vole. Jim clipped his fur (so we could tell if we catch him again) and released him into the long grass. Voles are quite laid back creatures compared to mice – their response to danger is to stay still in the hope of not being seen, which makes them relatively easy to handle. The woodmice we found in some of the other traps were a bit more challenging.

Jim the trap-happy field vole
Jim the trap-happy field vole

So, nothing more exciting than a field vole from the first check. Time to go home and try to warm up.

The traps need to be checked three times a day, so I still had a couple more opportunities to see a harvest mouse. I returned at lunchtime, and the whole scene had transformed. The mist had disappeared, and the sun warmed us as we worked. The vole we had caught and released that morning had found his way back into a trap. The next occupied box we found gave us a surprise. It felt like it was buzzing when I picked it up, and I expected a very angry mouse to bounce out, but it turned out to be a disgruntled wren, who flew off to safety. That was our lunchtime haul, but we were also treated to views of a kingfisher and a sparrowhawk.

wrenThe evening check felt very different again. The planes seemed bigger and closer in the dark, and we had to rely on torch light to see the traps. The same vole had found his way back into a trap. Having seen him three times in one day, we decided he needed a name, and settled on Jim. No wrens this time, but another woodmouse or two.

Sadly no harvest mice showed up for me. The traps stayed out the rest of the week. Rachel and a team of dedicated volunteers checked them three times a day, come rain or come shine. But no harvest mice turned up.

It was a worthwhile experience. I’ve seen a field vole and learnt how to distinguish it from a bank vole. I’ve learnt how to use three types of small mammal traps, and seen a kingfisher. And I’ve had a fascinating glimpse into the wildlife of Gatwick Airport. You can read more about biodiversity at the UK’s second busiest airport on the Biodiversity Gatwick blog.