Dormice and arborists
by Jon Price BA Hons, AATech Cert Arb of Ecosulis Ltd Jon Price is an ecological consultant based in the west country

I can remember the first time a grown man stood in front of me in a darkened wood, cupped his hands as if he were about to drink from a pool of fresh water and said the immortal phrase “. .it’s about the size of a grapefruit . . .”

No, he wasn’t a pervert, weirdo or even an MP - he was just the consultant ecologist contracted by Network Rail (through their engineers in that region) describing to me and my colleagues what a Dormouse nest might look like if we were to come across one whilst carrying out ‘de-vegetation’ works on the railway embankments of a Welsh branch line. This was the mid 1990’s, but I remember how he stood there in the autumn light underneath the attenuated alders that we were about to ‘de-vegetate’, scattered hazel, hawthorn, bramble and bracken all about, with his head bowed, hands cupped and a very slightly worried expression on his face. He could have been praying, I thought at the time. Maybe not praying to the Dormouse perhaps, but more likely entrusting their very existence in this particular stretch of habitat to the six scratched and scarred burly men before him, all armed with a variety of deadly power tools, scratched and patched PPE with a fleet of rumbling German and Scandinavian monster vehicles in tow. It was the first time I had come across the Dormouse, Muscardinus avellanarius, outside the context of the local Wildlife Trusts newsletter or the odd mood-lightening addition to a story in the local newspaper. We had learned all about protected species and relevant legislation at college, but the theory had seemed to evaporate in the cold light of day to day practice and job pressures. Our foreman eyed the alders, stretching into next month (and over budget) behind the ecologist as he described the distinguishing features of the Dormouse - their chestnut brown colouration, fluffy tail, characteristic ground based hibernation nests - and the contingency plan we were to follow if we found one. As it was, the job got finished on budget (just) and without major disruption to the rail traffic of South Wales - plus we found two Dormouse nests; beautifully sculpted, scruffilyy woven spheres of stripped honeysuckle bark, dried grass and sessile oak leaves with no clear entrance or exit holes. Like miniature balls wedged in the buttress roots of an over-mature hazel coppice, they could have been the prize of a particularly obscure treasure hunt. Our ecologist at the time was working under a licence from the statutory consultee, Countryside Council for Wales (being the equivalent to English Nature in England and Scottish Natural Heritage in Scotland), which permitted him to disturb a protected species. During the long drive to site and back, I had the opportunity to read more about this species and what made it different to any other mouse, and to share this knowledge with my team. The de-vegetation work we were doing on the railway embankments was, in all but intent, the finest conservation work for Dormice (and other woodland species) that money could buy. Unlike other small mammals, Dormice have a very complicated physiology and habits, asleep or hibernating for up to eight months of the year. Their dietary and breeding needs differ hugely from other, apparently similar species such as the wood mouse (Apodemus sylvaticus) or bank vole (Clethryonomys glareolus), which are in any given suitable habitat ten-times more abundant than the Dormouse. This underlines their position as relative specialists to a particular ecological niche. Where their cousins can range over a variety of circumstance and adapt to wider variations in conditions, the Dormouse relies on a particular mosaic of woodland habitats and narrow range of ambient temperatures to support a breeding population. Comparative life-spans underline this difference and specialism; Dormice in the wild are thought to live for between four and six years, whereas bank voles and most other mice would be fortunate if they saw their second birthday before they see the insides of a kestrel, owl or weasel. This is because they are, in evolutionary terms, embedded in the cycle of broadleaf woodland development and management that has been in such decline over the past century or more. They spend up to 80% of their time off the ground, climbing nocturnally through the hazel, thorn, bramble, dog rose, clematis, honeysuckle and oaks, sourcing food and bedding from extended periods of exertion interspersed with long periods of inactivity if the weather, or food resource wasn’t forthcoming. The diversity found in the structure of such woodland, from shrubs, climbers, maturing canopy species and the associated field and herb layer is what the Dormouse requires, but equally its loss, fragmentation, over-maturity and neglect is what has accounted for its significant decline. Whereas other small mammals have been able to adapt opportunistically to changing circumstance, the Dormouse has suffered greatly. This is why they are protected by law under the Wildlife & Countryside Act (1981) subsequently amended by the Countryside & Rights of Way Act, passed in 2000. As part of the European Union, the Dormouse is also protected under Annex 4A of the EU’s 1992 Habitats Directive, which was included under British law through the Conservation (Natural Habitats etc) Regulations in 1994. As tree surgeons, foresters and landscape professionals we often find ourselves working in exactly the type of environment and habitats that might support Dormouse and other protected species, (see upcoming issues of EuroArb!), and it is our legal obligation under the above legislation to ensure we are not impacting the favourable conservation status of those species. With all the best project planning in place plus centralized guidance for local authorities, statutory undertakers and general landowners (such as Planning Policy Statement 9 Biodiversity and Geological Conservation) conservation practice today is still a complex mosaic of people, professions, science and co-incidence much like the conditions vital to the Dormouse’s survival. As arborists and foresters we should be seen as a valuable and useful source of conservation data, much of our work, as described above already contributes albeit accidentally, to the welfare and survival of important species and habitats and it’s not a huge leap for these objectives to be combined. Just remember to take a closer look at the buttresses of the next over-mature Hazel (Corylus avellana) you cut to ground level; Dormice are not called M. avellanarius by coincidence!