12 Apr Changing Technology in Ecological Surveys: the Role of Thermal Imaging and Infra-Red Cameras
Over the last fifteen years there have been significant changes in the way many professional ecological surveys are carried out. In large part this has been driven by the standardisation of survey methods for many protected species (and species groups) brought about by the issue of widely accepted and endorsed guidance.
Advances in technology are also driving changes in the way survey work can and should be approached and it can be a challenge keeping abreast of available technology and its potential applications. An illustration of the pace of this change can be seen in the proliferation of different bat detectors over the past ten years. The sole use of a heterodyne detector, which is manually tuned in the field to identify bats based on the frequency of their echolocation, is now a distant memory: a range of equipment is used to ensure that acoustic recordings are taken for later analysis using (increasingly sophisticated) software, which creates a far more robust data set for assessment.
While some technological advances improve the ease and quality of data collection using established methods (such as improvements in bat detector technology), others have the potential to fundamentally alter the way we approach survey (such as the more routine use of eDNA analysis to determine likely presence or absence of great crested newts). Identifying the potential for new technology to add value to or replace more traditional survey techniques, particularly where these might reduce costs or risk to a consent, is therefore something we take very seriously.
Thermal Imaging and Infra-Red Cameras
Over the last few years BSG Ecology has been using thermal imaging and motion-activated infra-red cameras to supplement conventional survey and monitoring techniques. At some sites this has increased our confidence in our assessment work or in the success of features intended to mitigate impacts, as we have been able to capture footage on animals in real time rather than inferring activity or habitat use from indirect methods such as acoustic recordings or from field signs alone.
Motion activated cameras can be a very effective means of recording the use of habitats by a variety of fauna. As they are triggered by movement, the amount of footage generated is limited and can be cost-effectively reviewed.
As well as saving time and improving accuracy, a benefit of the use of motion-activated infra-red cameras is that they can allow unpredictable optimum conditions for focal species to be sampled much more effectively than traditional survey techniques. For example, we have deployed them successfully to sample newt use of tunnels under a major road, finding that animals move through them periodically and at a frequency unlikely to have been detected through visual survey. The alternative to this, pitfall trapping, would have been more intrusive and resource hungry.
Collecting the data on great crested newts was achieved by linking the cameras, infra-red lights and computer to mains power, and housing the hard drive in secure weather-proof casing. As a result we were able to record activity for a complete season with minimal maintenance. This has demonstrated the tunnels in question were being used by great crested newts and a range of other wildlife. Despite the fact that the cameras were deployed for an entire season, the footage was effectively reviewed in a few hours, thereby maximising efficiency and minimising cost.
We have also used motion-activated cameras for monitoring use of otter holts during restoration of a gravel pit, recording a range of fauna including badger, fox and rabbit using the same features over the course of a number of weeks of survey. In this situation, the data collected were successfully used to support a licence with regard to closure of one occasionally used holt (which was replaced with a new artificial structure above the post-restoration water level of the pit).
Thermal Imaging Cameras
Whilst highly effective and relatively cheap to deploy, infra-red cameras are restricted where observations are needed over longer distances or the subject of the survey is highly mobile. In these circumstances thermal imaging cameras can significantly increase survey accuracy, albeit at greater cost as they require staff to operate them. It is therefore important to understand which technology is most applicable to a project.
We have found hand-held thermal imaging cameras to be very effective at monitoring bat activity and the behaviour of nocturnal birds. Through careful selection of cameras and the use of a 45 degree lens we have been able to characterise bat flight activity at distances of up to 80 metres from the observer, allowing the nature of use of features and the number of bats using them to be recorded and correlated with data collected from static units. We have also used cameras to locate bat roosts in tunnels and trees and to assess swarming activity. Thermal imaging has also allowed us to record the nocturnal activity of golden plover and lapwing flocks (in relation to wind farms) without affecting their behaviour, and to confirm bat roost and badger sett occupancy (and count emerging animals).
To maximise our ability to make use of the cameras and to fully explore their capabilities we have invested in professional training of our staff through Thermal Vision Research Ltd, and Senior Ecologist Laura Grant has recently attended and passed a Category 1 thermography course run by the Infrared Training Centre. Through this additional training she has learnt more about the scientific principles of infrared technology.
As new technology becomes available and/or affordable, constant reflection on how we approach ecological survey is required if we are to identify opportunities to survey more effectively and accurately, thereby reducing planning risk and costs for our clients.
The next obvious step forward is likely to be the use of drones to inspect areas that are too inaccessible (often due to health and safety concerns) for conventional survey, such as the roofs of derelict buildings, areas of steep cliff or open intertidal or riverine mud. In such circumstances high resolution video and still footage obtained from drones can be very useful in supporting an assessment of, for example, bat roost potential or vegetative cover. This is an area that BSG Ecology is experimenting with; the use of drones has already been incorporated in project work.