Observing nocturnal animals is usually done with a spotlight. This is fine for many mammal species, as they tend to look in the direction of a bright light and have bright eye-shine – they are easily detected. You can then train binoculars or camera onto them for identification. This has been a tried and true method for decades, but has had one significant failing – some mammals don’t have strong eye-shine (usually because they are small), don’t look at the light, or are so busy moving through the tree-tops that they are difficult to detect. Hence, some species are ‘data deficient’ – they are rarely recorded, because they are difficult to detected.
Mammals, being warm-blooded, radiate heat (infra-red radiation), which means they can be ‘seen’ with equipment that detects heat. Even a few years ago IR, or thermal imaging equipment was well beyond the reach of most ecologists and naturalists, but that has now changed. Driven by military investment and demand from recreational hunting, the application of thermal imaging technology to wildlife observation is now within reach.
Not only does this technology increase the detectability of cryptic species like pygmy possums and sugar gliders, but it allows observation of more natural behaviour, because the animal isn’t in a bright beam of light. I have spent many hours spotlighting for wildlife in the forest around my home and very rarely do I see Sugar Gliders. I know they occur in the forest, as they are occasionally heard calling, but they are small, quite active, rarely sit to look at the light and have faint eye-shine. With the thermal scope, I now see them most nights when I’m out looking – and they are fascinating to watch!
Thermal imaging also ‘illuminates’ things not often considered eg. those parts of an animal’s body that emit the most and least heat. It’s a completely different way of exploring the night and promises to improve our understanding of how and where animals live in the landscape.
Here are some examples of my early IR observations from the forest habitat around our home.