A night in the forest

I may be 38 weeks pregnant but that is not going to stop me following my interest and passions, within reason of course.

So 8pm on a Thursday night finds me standing in chest high bright green bracken in a patch of forest. On all four sides the tall dark green of dense pine trees surrounds this opening. Above the darkening sky is overcast with just a hint of pale gold touching the underside of some clouds as the sun sets. It is very still, not a breath of wind troubles the pine needles or the curling fronds of bracken. Beneath the canopy brown needles have collected along with dead branches that crunch underfoot. Out in the patch beneath the bracken the dusty soil kicks up with each footstep as we head through the bracken in search of a suitable place to position our net.

In the forest setting up nets

The last few strains of bird song drift through the air, a robin, song thrush and the odd woodpigeon settling down for the night. With the net set we settle on the carpet of pine needles just within the shelter of the trees and wait. The colour drains from the surrounding landscape, the bright green of the bracken turning grey. Against the darkening sky the silhouette of a tiny bat darts across our view, twisting and turning with fluttering wings. A larger bat dashes by, a bold black dot with distinctive shaped wings. Amongst it all a new call begins to echo across the forest and its open spaces. A continuous churr followed by a soft coohick. Then there is the sound of clapping before the source of the unusual sounds is revealed. From the trees and swooping overhead in almost silent flight, comes a dark shape with pointed wings and a long tail. The flight can be direct, but also bouncy, with the bird swooping low to skim the bracken before lifting back up and away over the trees. Still although out of sight the distinctive churr picks up again. This is the nightjar.

Unfortunately and it seems like many of our distinctive migrant birds the nightjar has experienced major population declines. Fortunately like many of species there are individuals and organisations out there working to understand these declines and the movements and requirements of such species. Nightjars in Britain have actually increased in breeding numbers in recent years (whoop!) thanks to a number of conservation measures. However they are still Red Listed and we still know very little about their movements outside of the breeding season. For a number of years the British Trust for Ornithology has been conducting a tracking study of the nightjars looking at not only the habitat they are using for nesting and feeding during the summer on our shores, but also where they are going during the winter. We know that the species winters in Africa and that they pass through places like France and Spain enroute, the tracking allows us to work out the detail.

And so with a couple of birds drifting around us it was time to try and catch one. With the help of a system playing the churring call of the male it was not long before one came into investigate and was caught in our mist net.

The type of tags the team from BTO have been using are known as geolocators, these record light levels allowing position to be calculated by day length and the time of solar noon. More recently novel GPS tags have been used. Both require the birds to be re-caught in order to down load the data. Hence the intensive effort each breeding season to catch the birds.

Tonight our bird did not have a tag and was also not ringed. But this gave the team the opportunity to attach one to it in order to track its migration south.

A beautiful nightjar

Up close the nightjar is so cryptic it is stunning. The grey-brown mottled plumage with fine streaks on the breast provides the perfect camouflage against the scrub, heath and dead branches of the forest floor during daylight hours. We know it is a male from the brilliant white patches on the wing and tail. The fresh, consistent plumage indicates it is an adult (born at least 2 years ago). Large dark eyes sit on a relatively large head that appears all feather and has a tiny beak with sturdy bristles along its closed mouth, used for detecting its prey at close quarters. But that mouth holds a secret, give it time and the tiny beak will open revealing a huge wide open gape capable to engulfing moths.

With a new metal ring and a tag securely attached the bird is ready to return to the dark forest. It sits unhindered for a moment on my hand, its eyes getting re-accustomed to the dark after the torch light. It feels like no weight at all. Then with one dip of the wings it is off becoming once again the churring, wing clapping shadow against the night sky, only this time it will also be collecting valuable data to help its entire species.


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