BTCV Handbooks Online

Book:	Woodlands
Chapter:	12 Woodland habitats
Section:	Mammals
Metadata:	Details	Buy this book

Bats

All British bat species feed on insects associated with trees, and woodlands, copses and hedgerows are vital for their survival. All bats and their roosts, whether in use or not, are protected by law (see trees and the law).

Bats naturally roost in cavities and other sheltered places in mature, old and dying trees, with oak, ash, beech and Scot's pine preferred. Bats also roost in caves, and in buildings of many types. Bats in buildings face problems of disturbance, intolerance, and danger from toxic timber preservatives.

Habitat management for bats follows the general guidelines appropriate to woodland management for biodiversity:

If planting, use native species, preferably of local provenance. These will support the insects on which bats feed.
Retain dead, dying and mature trees, and those with holes, splits and broken branches. Do not 'tidy up' trees for appearance sake. If there is danger to the public, consider other measures, such as fencing off the tree, to allow it to be conserved. Legal requirements regarding bats (see trees and the law) must be considered.
Retain or encourage ivy on trees, as this provides bat roosts and insect habitat.
Provide and manage glades, rides and sheltered open spaces which will encourage insects.
Encourage a diverse woodland edge habitat.
Maintain or plant hedgerows, lines of trees and other woodland corridors. These are not only important in supporting the insects on which bats feed, but are also vital features which bats use to find their way around the countryside at night. A gap as short as 10m can deter bats, and cut off routes between roosts and feeding sites.
Ditches, ponds and marshy ground are important bat feeding areas.

Management work

Woodland management work which may disturb bats should be done in spring (March, April, May) or autumn (September, October, November), as this avoids the most vulnerable periods when bats are hibernating or non-flying young are present. The legal requirement not to disturb bats or their roosts must be followed (see trees and the law).

Bat roosts are found in holes, cavities and splits in trees. Look out for dark staining on the tree around and below a hole, tiny scratch marks around the hole, or any squeaking or chittering sound from a hole, especially on a hot day or at dusk. Droppings, which crumble to a powder, may be found below holes.
Watch for bats emerging after sundown, or returning at dawn.
Retain any trees known to be used by bats, and those trees adjacent. Avoid removing maturing trees which may be suitable for bats in the near future.
Avoid or minimise tree surgery work which may adversely affect bats.
Seek specialist advice from your local bat group (contact English Nature or the local Wildlife Trust for details).

Bat boxes

Bat boxes cannot replace natural roosts, but they can be an important addition in habitats where suitable roosts are scarce.

Bat boxes should be made of preservative-free, rough sawn, and preferably weathered timber, at least 25mm thick. Concrete/sawdust boxes are also suitable.
Site boxes close to a continuous linear woodland feature such as a line of trees, hedgerow or woodland edge, which bats use for feeding and navigation.
Boxes should be firmly attached (see birdboxes and other nesting sites) as high as practicable in trees or on buildings or other structures. On buildings, fix the boxes under the eaves to be safe from cats and other predators.
Site boxes where they are sheltered from wind, and in the sun for part of the day. Ideally put up three or more at each site, facing from south east through to south west, providing a range of temperature conditions.
It may be several years before bat boxes are used. Never open a box, but look for droppings, urine staining and other signs of occupation. Avoid any disturbance between June and mid-August, when bats are giving birth and lactating.

Use the cutting pattern shown, and fix together with waterproof glue and screws. Secure the lid with screws, so that it can be removed by a licensed bat handler, while deterring others. The box should last at least 10 years, and longer if durable hardwood is used.

For further information contact your local Bat Group, or the Bat Conservation Trust (see appendix B). A selection of 'woodcrete' boxes designed for different species of British bats is available from Jacobi Jayne & Company (see appendix B).

Badgers and foxes

Foxes are common in most areas where there is sufficient food and cover, and will be present in most woodlands and copses, especially near urban areas. Badgers are also associated with woodlands, and will make their setts in sandy or other easily excavated soil in woods, copses, hedgerows and other uncultivated places. When fencing new or existing woodlands against rabbits, deer or stock, take care not to fence across established badger runs, as the badgers will burrow under or break through the fence, making it no longer proof against other animals. If fencing across a run is unavoidable, install a badger gate. See Fencing (BTCV, 2001) for details. Badgers and their setts are legally protected (see trees and the law).

Deer and rabbits

These are often pests of woodland, and measures to prevent them eating young planted trees, natural regeneration and woodland flora are often necessary. See planting and early care and coppicing.

Small mammals

Small mammals are encouraged with plantings of native berrying shrubs which provide food, and by plenty of undergrowth and other cover. Hedges, hedgebanks, dry stone walls and piles of logs, stones or rubble provide valuable cover for many small mammals. Provision or retention of such features will provide habitat for a variety of animals.

Voles and squirrels can become pests in woodland, because of the damage they can cause to newly planted and pole stage trees (see young woodland).