Protecting the hazel dormouse in Oxfordshire and Berkshire

© Helen Miller

article written by Elliott Cocker 

One of the most charismatic wildlife species found in Britain, the hazel dormouse (Muscardinus avellanarius) is the focus of significant conservation effort, as a symbol of the idealised British woodland. Despite this ongoing attention the species has received, it has been categorised as ‘vulnerable’ in the UK by the Mammal Society, and has experienced an estimated 72% population decline between 1993 to 2014. Why have the energy and resources poured into hazel dormouse conservation failed to protect the species’ population?

In the context of Oxfordshire and Berkshire, we might approach the issue of hazel dormouse protection by assessing the coverage of its range by the various protected sites in the region. Using GIS, it is possible to simultaneously map protected sites with the locations of TVERC-verified dormouse surveys. This enables us to see the extent to which the existing protected areas encompass confirmed hazel dormouse habitats.

Figure 1 displays this mapping, showing us the locations of all survey points upon protected sites of all designations in the region. It is important to note that hazel dormice were not necessarily recorded at each site; only 297 of the 1356 surveys compiled by TVERC recorded at least one dormouse. It is apparent that most of the survey points occur within the various protected sites; most notably including a cluster of 1,032 hazel dormouse surveys within 1.5km in South Berkshire, in the protected areas of Bowdown Woods and Greenham and Cookham Commons. At the outset therefore we have a shortage in the scope of our data, and a need for more widespread surveying for the species to better determine its range. Throughout Oxfordshire in particular, the lack of survey points is apparent, and the failure to monitor incidence of the species outside protected areas limits the ability to pinpoint sites for expansion of protected space to better conserve the population.

Given the lack of surveying outside of protected sites, it would be inappropriate to conclude that protected areas cover such a high proportion of the species’ range as suggested by this data (>90%). We can only state for certain that over 90% of the confirmed range is covered by protected areas. At the very least, this tells us that there are documented hazel dormouse populations within the region’s protected areas. While we can begin to tentatively point to sites for expansion with the available data, in the absence of more comprehensive surveying, we might instead shift our focus to consideration of how effective our protected areas are in preserving this population of the species. It is not enough to simply draw a line around our wildlife and designate it protected; we must assess whether our protected sites are fulfilling the needs of the species they are designed to protect.

This is of particular relevance to the conservation of the hazel dormouse. As stated earlier, it has been at the centre of conservation effort in Britain, yet its population has still declined sharply in recent decades. Protected areas have apparently not fulfilled the needs of the species; indeed, it has been suggested that protected areas, in some cases preventing traditional woodland management practices such as coppicing, can be linked to reduction in early-successional forest habitat (generally smaller, less mature trees and plant life). This is the type of habitat in which the hazel dormouse thrives. Therefore, of chief importance is the facilitation of early successional forestry, which provides the best quality habitat for dormouse nesting, hibernation and reproduction. This may be achieved by allowing controlled areas of coppicing and other traditional woodland management practices to artificially produce and sustain early successional habitat. There is also a highly ambitious and tentatively suggested option: the reintroduction of keystone, ecological engineer species such as the Eurasian beaver, to the region, which naturally coppices trees, to increase habitat diversity. Of course, this would require a great deal of in-depth impact assessment, but any measures which increase the availability of early successional woodland habitat would likely be beneficial to the region’s hazel dormouse population.

So what does all of this tell us? The main conclusion from this assessment is that much greater, more widespread surveying is needed to better map the range and population status of the hazel dormouse in Oxfordshire and Berkshire, particularly to identify more sites of dormouse incidence that might benefit from protection. Even within existing protected areas, however, facilitation of early successional forestry, not simply protection of maturing forests lacking engineer species, is vital to the sustenance of the hazel dormouse and other wildlife. While we should not always treat declines in individual species as an ecological problem- declines in the dormouse might for example be partly linked to positive increases in populations of birds of prey and mammalian predators- enabling habitat diversity should be a priority of conservation efforts. For the hazel dormouse in Oxfordshire and Berkshire, gathering more data and reviewing woodland management practices should be the focuses for protection of the species.

Posted: January 4, 2021