Thermal Imaging as a specialist bat survey technique

11.04.2019 3 min read

Surveying nocturnal animals poses unique challenges for field ecologists, especially when surveying small mammals such as bats. Bats usually emerge after sunset and low light levels make obtaining accurate observations difficult with the naked eye. One way of overcoming these challenges is to use a thermal imaging camera.

How does thermal imaging work?

Thermal imaging (TI) does not rely on light levels but instead detects infrared radiation to produce images called thermograms. These thermograms allow variations in temperature to be viewed on a screen.

Bats, like other animals (such as the badger pictured below), produce metabolic heat forming a distinct thermal image against a cooler background when viewed through a TI camera lens.

What are the advantages of using TI as a bat survey technique?

The use of thermal imaging cameras for surveying trees and built structures makes it possible to obtain accurate information on roost locations and counts of bats emerging and/or commuting.

Not all bats will emerge from their roost before it is too dark to see them. Therefore, thermal imaging cameras are a non-invasive method of detecting the individuals, by providing a clear view of objects that are a different temperatures to their surroundings, without using artificial lighting.

The accuracy of the thermal imaging cameras also means it is possible, in some cases, to reduce the number of surveyors required, which therefore lowers survey costs while increasing result precision.

What type of projects can TI be applied to? 

We have an experienced team of specialists (including qualified Thermographers) trained in the use of this high-level technology and can tailor our surveys to the specific needs of your project.

Our specialists have extensive experience in using TI cameras to survey bridges, trees and buildings, including churches, and have applied this survey technique on large infrastructure projects in the rail, airport, and highways sectors.

Bats near wind farms and linear infrastructure schemes

This technology is particularly beneficial for use on road and rail infrastructure schemes; the camera lens’ long-range detection enables surveyors to be positioned in an area of safety whilst still ensuring that the survey area is adequately covered. We have applied this method to survey motorway bridges, bridges crossing rivers and railway infrastructure.

We have been applying a similar approach to determine bats’ key crossing points and the level of commuting activity along linear infrastructure corridors and near wind farms. These surveys have been used to inform mitigation at key locations to reduce the risk of these bats being harmed by fast-moving objects (trains, vehicles, aeroplanes, wind turbines).

As part of an ongoing research project, The Ecology Consultancy’s specialists are working on developing a collision risk survey methodology and statistical model that will be applicable to large infrastructure projects such as airports, railways, roads and wind farms.

Bats in churches

We have also used thermal imaging cameras on sites with large bat roosts, including several churches across the UK. This allows us to determine accurate counts of the roosts in order to define the importance of the roost within a local context.

The results of our surveys have contributed to the Bats in Churches partnership project which aims to design appropriate and novel bat mitigation techniques to enable the church community and bats to coexist without resulting in the loss of important bat roosts or unsympathetic modifications to historical, listed buildings.

How else can thermal cameras be applied?

Thermal cameras can also serve as an invaluable tool for monitoring populations of other nocturnal mammals such as badgers. Thermal surveys have been carried out in the UK to successfully monitor mitigation measures such as motorway underpasses for badgers and other wildlife.