All 16 species of British bats rely on trees and woodlands to some extent. Trees provide valuable foraging areas, shelter from weather and predators and represent key connections between different parts of the landscape. The most important use of trees by bats is for roosting and all species are known to use them to a greater or lesser extent. Trees are used by females as maternity roosts in spring and summer, mating roosts during the autumn and for hibernation during then winter. The Noctule bat, a species almost entirely dependant on trees for roosting. This species, which can have a wingspan of up to 30cm, has declined dramatically in Essex probably due to the loss of suitable roost sites.

The presence of bats must be considered for all work affecting trees from pruning to forestry operations. For individual and small groups of trees one should consider the possibility of bats being present if any of the following are present: natural rot holes, woodpecker holes, cracks/splits in major limbs, loose bark, ivy, hollows and cavities, dense epicormic growth and within bird and bat boxes. Remember the smaller species of bat can pass through a 12mm gap or less.

If you have reasonable high pitch hearing it is possible to hear audible squeaking at dusk or during warm weather coming from roost sites. There are other signs that might indicate a bat roost in a tree but they need an experienced eye. Many roosts, unfortunately, give no indication at all of bats being present.

If you are unsure or need extra advice contact Natural England (phone number below) who will probably send out a Licensed Bat Worker. The advice and visit are FREE. It can also save time and expense when work has started as most reputable tree surgeons are increasingly seeking advice from English Nature when working on trees with potential roosts. The sail area of a tree can be reduced considerably by removing a third or less of the canopy but at the same time retaining the features that can be used by bats and other wild life.

Potential bat roosts sites should also be considered when looking at applications for work on trees. If roosts are suspected and bats are known to forage in the area comment should be made to the planning department.

Roger and Sylvia Jiggins Joint Secretaries of the Essex Bat Group  Tel. 01376 324 311

Email r.jiggins@btconnect.com.

Essex Bat Group  Web site www.essexbatgroup.org.uk

Bat Conservation Trust  Web site www.bats.org.uk. Tel. 0845 1300 228

Natural England, Essex    01206 796 666