Seeing in the dark

Last night, Mike and I were locked inside a forestry plantation in Cwmcarn. It seemed certain that we were going to spend the night in our cars. This is not an unusual situation for people who work in remote places at night and its not the first time we have had to drive around in the dark on bumpy tracks looking for access gates.

We have been commissioned by Natural Resources Wales to do a thermal aerial survey of one units they want to restock with Sitka and Norway spruce. We are trialling a technique to survey for the presence of nesting birds, particularly nightjars- who have a particular liking for upland clear-fell areas. It is a great project using slick technology and it has clear practical applications in conservation and industry. 

Facilitation of conifer plantation might seem like a counterintuitive conservation strategy to maintain populations of nightjar, and perhaps in some respects it is. The first way that it is a positive conservation strategy is that, if successful, the location of nesting nightjars will be identified and protected for the duration of their breeding season. Illegal or not, killing a brood of nightjars by running a mulcher over them, isn’t going to help the population.The second way is, regardless of how you might feel about conifer plantations in the uplands, at various periods in their timespan they are valuable habitats for nightjars, not just after they have been cut down but also in the early growth phases. I am less keen on the main period of stand growth, but I suppose we need timber.

the black spot is the cold (bright yellow) landing pad and the white blob is a (black) labrador

detail is sparse at 15m height

Thermal imaging is like having superhuman vision- or like being a spy in MI5 and it is very tempting to fly around all night looking for anything that has a heat signature.  It also has its downfalls that make the whole enterprise slightly more complicated than a standard aerial survey. Thermal imaging is most effective when there is a temperature differential between the (warm-blooded) creature and the surrounding environment. This happens best at night when the temperature drops- it works even better at dawn when the ground has really cooled and there are no residual hot pockets. Working at those hours really eats into your rest time (that seems to matter more to me as I get older!- although I fell asleep on the minibus today- I wasn’t driving, happily). The other downfall is that the thermal sensor is not as high resolution as cameras- so you need to fly at low heights to get good detail. Flying at low heights is bad because it requires more flight time to cover an equivalent area. Also there are more obstacles like trees at low heights.

We are yet to find a nightjar nest, not because the technique isn’t effective, but because they are few and far between. Its only a matter of time. Watch this space..