My Love of Recording Mammals - NMW Blog
Written by David Groves of Cornwall Mammal Group
I guess the collecting gene probably evolved when my (distant) ancestors were scurrying around in the undergrowth collecting seeds to last them through the winter. I’ve always enjoyed collecting records of wildlife, partly I think it is competitive and partly a desire to understand where we fit into the world around us. Anyway, when Cornwall Mammal Group (CMG) were working on our 2012 Cornwall Mammal Atlas it became very clear that information on many mammal species was very thin and often told us more about the location of recorders than anything else. Records are particularly sparse for our smaller terrestrial mammals, even though they are critical to the survival of other more iconic species. I’m in awe of good wildlife trackers, but regular filed surveys, a good camera, a little patience and a few good test books can take you a long way.
Longworth trapping is a great way of getting to see these animals, but a really time consuming and inefficient way of collecting distribution data, so I have always been keen to find easier routes. Cat kills and road casualties have been good for some species, digital photography has been productive. However, the most useful methods of recording are based around evidence left by particular species – so we have used otter spraint (droppings) to collect plenty of data for an animal only rarely seen. For smaller species droppings are less reliable but feeding signs can be very productive. Many of our records of field voles, a species that is perhaps under-represented in trapping surveys, come from observations of their characteristic larders of neatly cut grass stems. There are several CMG members (including myself) who cannot resist peering through the grass in search of these at every opportunity. In the Autumn, fallen hazelnuts provide clear evidence of wood
mouse, bank vole and (most excitingly) dormouse in Cornwall as each species opens the nut in a distinctive way. When droppings and feeding signs can’t deliver its is necessary to think outside the (owl) box. Owl pellets are a great way of recording – especially the pellets of barn owls which hunt within a relatively small radius of their roost. Nothing fills those long Winter evenings like picking through rancid owl pellets. CMG collaborate with the county bird groups to collect pellets from monitored roosts, subject to all the rules and regulations, of course. Owls are a lot better than ecologists at collecting small mammals, particularly shrews, and since it is easy to identify shrews to species level from their tiny skulls this has been a great to amass distribution data for these under-recorded insectivores.
Tracking larger animals is straight forward compared to looking for footprints of mice and shrews – it is difficult to tell mice from voles, or water shrews from common shrews but one species where this can work well is the hazel dormouse. We have been using tiny footprint tunnels (similar to the hedgehog tunnels with ink pads and paper) up in the shrubbery to pick out the distinctive prints.
Nests are another great way of monitoring small mammals. Two species in particular build very distinctive nests: the hazel dormouse and the harvest mouse. I have been involved in long-term monitoring of a number of sites as part of the National Dormouse Monitoring Programme using nest boxes where the dormice set up home (sharing with birds, shrews, wood mice and the occasional toad). Although this works well on established sites it is much more difficult to find ‘wild’ nests which are well camouflaged and hidden away. Some people seem to have a sixth sense for finding wild nests, not me.
Field vole nests are not uncommonly found when searching in grassland but this is one of those pieces of evidence that I’m never 100% sure about – I prefer to have feeding evidence to back them up. Which brings me to harvest mice – my ideal subject: firstly they have been highlighted as ‘near threatened’ on the recent IUCN Red List for Britain's Mammals; secondly there are very few recent records for Cornwall; and thirdly there is a simple, reliable method of recording them which has limited welfare concerns. Importantly, the National Harvest Mouse Survey has provided us with a structured survey, moving away from incidental records such as sightings or road kills and from intensive and expensive surveys methods such as trapping, we have a better approach to understanding distributions and populations, and more importantly monitoring change. I had been looking at harvest mouse recording for a couple of years but the Mammal Society project was the boost I needed to get trained and get out there recording. There is a great buzz walking onto a new site (generally in the pouring rain….) hoping to collect a new record for the map. I’ve also found the surveying to be a great social event – especially after all the issues of lockdown – it is something everyone can do and there is a site close to most people. The camaraderie of the Harvest Mouse Team has been inspiring and the links with other regions and the national team has also been very productive. I hope people who have taken part will join in with other surveys and projects in the future.
Of course, there is no point in collecting this information if it sits in a notebook on a shelf! I have always tried to encourage everyone in Cornwall to submit their records to the Local Records Centre, ERCCIS. CMG’s County Mammal Recorder supports the records centre with any queries. I’m hoping that this year we will be able to carry out harvest mouse surveys in each of the 55 hectads across the county and maybe begin to focus down to tetrad level next year. More usefully we need to correlate this with landcover information to see if harvest mice are present in all suitable habitat and if improved habitat is reflected in increasing numbers of mice. I suppose it will keep me out of trouble anyway.
This blog was written by David Groves who is the current chair of Cornwall Mammal Group and lifelong mammal enthusiast .
The theme for National Mammal Week in 2022 is Recording Mammals Around You. Did you know that mammals are some of the most under-recorded species in Britain! With one in four of our native mammals threatened with extinction, and many others are in decline we need your help. Consider becoming a member of the Mammal Society today for as little as £3 a month.