Forestry: How sustainable forest management could save the dormouse

IN case you have never come face to face with one, the hazel dormouse (Muscardinus avellanarius) is a small native rodent with golden brown fur, large black eyes and long whiskers – and the only little British mammal with a furry tail. They are active in late spring, summer and early autumn in the trees and shrub canopy and hibernate in a nest on the ground over winter.

This small native rodent should not be confused with the far larger alien fat or edible dormouse (Glis glis), which is present and well established in central England radiating out from the Chilterns and can reach pest proportions in dwellings and forestry.

STATUS AND DISTRIBUTION

Orchestrated by the People’s Trust for Endangered Species or PTES, every few years an army of volunteers monitor the success and failures of this native dormouse. 

The latest survey from 2023 suggests a total GB population of 930,000, but there is some uncertainty around this estimate. That is a crash of over two thirds since 2000. It is believed to have disappeared from a score of English counties. This creature is nowadays only found south of a line between Flintshire and Suffolk. 

A PROTECTED SPECIES

At rest. (Image: Szymon Bartosz)

Hazel dormice are protected in the UK under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017. They are also a priority species in the UK Biodiversity Action Plan. 

You may be able to get a mitigation licence from Natural England or NRW if you can’t avoid disturbing them or damaging their habitats, for example during forestry operations. 

The Forestry Commission has a protocol for managing woods inhabited by this protected species.

ANY AROUND?

As a protected animal, only licensed folk can handle them. But there are other ways of discovering if this creature is still around in your woodland, if you wish to give them a try.  A quick and easy means of checking for this animal – avoiding hours poking round for nests in the undergrowth – is to check out any discarded hazel nut shells. Each class of animal feeding on these nuts opens them in a telltale way – so no need to actually see or handle the creatures. The PTES website explains more. 

Putting up tree tunnels is an alternative. These are just what they sound like – plastic or wooden tubes attached horizontally along branches transited by wildlife. 

In each contraption is a section with an inked floor and a white paper one that picks up the paw prints of whatever creature ventures through. And the tiny foot prints of dormice are easy to identify. 

That is also one way to put square tree tubes to a practical use. 

So how come this tiny member of our fauna has come to this plight, and what can be done to save it?

CONSERVATION MEASURES

Wildlife organisations have devised various ways of helping to save this charismatic creature.
Nestboxes have been designed over the years that are tailor-made for these dormice and are shown on websites. These are available for anyone to put up, but should only be checked by licensed handlers.

Surviving dormice can persist in a variety of habitats, particularly old managed woodlands linked by continuous hedgerows. Their long-term decline reflects the loss of many old woodlands over the last century, the lack of management of those remaining and grubbing up of hedgerows no longer needed to enclose livestock.

Black plastic and wood dormouse (Muscardinus avellanarius) nest tube survey box attached underneath a tree branch. (Image: John Biglin)

Where hazel dormice are still around, they are fully arboreal and nocturnal. Moving at night through the often poorly connected tree and shrub canopy can be challenging, so dormice don’t travel very far to feed nor cross open ground and are relatively sedentary in their woodland homes. When they wander further afield to disperse as juveniles, they do need good tree shrub and hedgerow connectivity to be successful within their home woodland or beyond and avoid ending up as a snack for predators.

To assist them in crossing safely from one place to another in fragmented habitats, and disperse as juveniles, rope ladders have been tried with some success, strung between one suitable environment and the next to aid dispersal – a murine ‘Go Ape’.

But loss of suitable habitat must be a major factor. 

REINTRODUCTION

PTES and collaborators are striving to prop up populations by releasing captive-bred animals. Over the past two decades, over a thousand of these tiny creatures have been released back into the wild.

An example to hit headlines this summer was the secret Forest Enterprise woodland in Bedfordshire and, in 2023, efforts to establish a viable population in the National Forest in the English Midlands. 

A phased release into a Natural England property in Lancashire is scheduled by now, to recreate a northern stronghold.  

To bolster genetic variation and resilience, the dormice released are drawn from stocks across the UK, screened for fitness before release and afterwards in their acclimatisation release cages in their newfound homes.

Others may be rescued and relocated from major infrastructure developments destroying their habitats and making them homeless.

WHY THE DECLINE?

As a rather specialised feeder in an artificial man-made habitat and a slow breeder, it can be real trouble when conditions change for the worse.

It seems fairly safe to deduce that the huge waning in the area of worked hazel coppice has had a knock-on impact on the many wildlife species that had come to benefit from this ancient form of management.

This traditional craft has been practised in the UK for eons. By the early 1900s – decades after the heyday in coppicing – it was estimated there were still in the region of 2,300 hectares of productive managed coppice woodlands across the UK. By 2003 this had plummeted by nearly 95 per cent.

Hazel coppice cants predominate, although there are areas of sweet chestnut in south-east England and local oddities such as lime or oak.

THE OUTLOOK

Dormice are thought to be declining because of:
• inappropriate or lack of long-term woodland and hedgerow management
• fragmentation of woodlands and hedges 
• our variable maritime climate of warm winters and wet springs that sometimes lead dormice to wake more frequently from hibernation and feed poorly in the spring. That may adversely affect their breeding success.

Climate change, as well as declines in woodland management, farming practices and loss/grubbing of hedgerows, have all taken a heavy toll on their living space. Dormice are good indicators of animal and plant diversity, and dormouse-friendly habitats are also good for woodland birds, bats, butterflies and biodiversity in general, which is why eclectic organisations are working hard to reverse the decline and promote recovery in British woodlands.

Hazel dormice rely on good tree and shrub diversity to provide them with food when they are active. They will feed on shrub flowers in spring, insects over the summer and fruit and nuts in the autumn. Their specialised diet isn’t available over winter so they must hibernate on the ground for about five months until the following spring.

Coppiced wood stacked. (Image: Steven Corton)

Such a long hibernation reduces their activity. And they generally produce only a single litter of four young, usually late in the year in August or September. On average dormice live for three years but they can subsist up to five in the wild.

Dormice prefer the new growth of woody vegetation that arises after woodland management such as coppicing, ride-widening, thinning or glade creation. In the UK, they tend to favour old worked coppice but they’ve also been found in scrubland, old hedgerows and sometimes even young conifer plantations.

A COPPICING COMEBACK?

Commercial coppicing and conservation often go hand in hand. Yet working coppice nowadays accounts for less than one per cent of woodland cover across the UK lowlands. There is a resurgence in interest in coppicing, especially for conservation goals by wildlife organisations.

Ongoing surveys launched this year in two regions of England through the Small Woods Association aim to catalogue where coppicing does still take place or could make a comeback.

Yet another example of how sustainable forest management aids biodiversity.