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You can contact Stuart Spray Wildlife Consultant at the following addresses:

England: 9 Basford Road, Manchester M16 0FT

Scotland: SSWC. Laundry Cottage, Clarencefield, Dumfries, DG1 4NA

Phone: 07894 081164

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Bat Surveys of Trees

We conduct bat surveys of trees throughout Wales, northern England and Scotland.

Most British bats have evolved to roost in trees. Features such as rot holes, cracks, flaking bark and old wood pecker holes can all be suitable for roosting bats. Many mature broadleaf trees are also important for a host of other wildlife and for their landscape and cultural values.

Unfortunately, our mature trees and the wildlife they support have for many years been under threat from misunderstanding and poor management. Many trees, thought to be dying or dangerous, continue to be unnecessarily felled or damaged by inappropriate tree surgery. It is not known how many bat roosts are been lost each year as a result of this type management.

UK legislation requires landowners and developers to carry out a bat survey for roosts prior to tree surgery taking place.

This page describes a three stage methodology for surveying and assessing trees’ potential for roosting bats.


This methodology is agreed as best practice by Natural England, Scottish Natural Heritage, Natural Resources Wales and The Bat Conservation Trust.

Stage One – Ground Survey

Trees are surveyed from the ground with the aid of binoculars looking for features capable of supporting bat roosts, including rot holes, cracks, splits, woodpecker holes, folds, overhangs, wound callus rolls and flaking bark, and will be identified as one of the following categories:

A ground survey can take place at any time of the year.

Stage Two – Aerial Inspection

All trees identified as having unknown or high potential in the Stage One ground assessment are inspected from rope and harness or Mobile Elevated Work Platform with the aid of an endoscope and are allocated to one of the following categories:

The aerial inspections are carried out by licensed bat workers who are experienced in using endoscopes and qualified to climb trees.

The numbers of bats, species and location of exit holes are recorded using maps and digital photography.

An aerial inspection can take place at any time of the year.

Stage Three – Dawn and Dusk Emergence and Re-entry Surveys

During spring and summer an emergence count, with the aid of Anabat SD 1 and SD2 bat detectors, is recommended for roosts where bats are present to ascertain the number of bats using the roost and confirm the species. Numbers of bats, species, emergence times and location of exit holes are recorded using maps, digital photography and infra-red cameras.

A stage three survey is also highly recommended for trees with large cavities that can not be fully surveyed with an endoscope due to its size.

Licences to disturb European Protected Species 

Where possible, it is recommended that proposed developments avoid all trees with confirmed roosts and also those identified as having high potential for roosting bats.

However, if this is not possible a European Protected Species (EPS) license to disturb/destroy the confirmed bat roost(s) will be required from Scottish Natural Heritage, Natural Resources Wales or Natural England before any work on the trees can commence.

A Bat Mitigation Plan is required as part of the application process.

Stuart Spray Wildlife Consultancy can prepare Mitigation Plans and guide you through the licence application process.

The footage below is of the Leisler’s maternity roost at Culzean Castle in south Ayrshire which was discovered during the  Scottish Leisler’s Bat Project.

The roost was not originally spotted from the ground despite being large and obvious when the tree was climbed.

The film shows how useful camcorders are for accurately recording the number of bats leaving a roost. The use of infra-red or thermal imaging means the counts can be accurate even in dim light or the pitch dark.

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