Geolocation, geolocation, geolocation

Female Nightjar on nest. Photo  © Jacques Turner-Moss

Over the past month and a half I've spent pretty much every night out tagging, tracking or nest-finding Nightjars at two sites at either end of Wales. Both sites are major wind farm developments in the construction stages and the Nightjar monitoring is part of agreed planning conditions aimed at avoiding disturbance to breeding pairs and assessing any effect of the developments on the resident Nightjar populations long-term. Two or three years of pre-construction monitoring at each site will be followed by post construction surveys and the results can then be used to inform any similar future developments.

One of this year's nests in South Wales was very close to a major track upgrade and, whilst I was sure the passing lorries etc wouldn't disturb the birds during the day as long as a suitable buffer zone was instigated, the earthmovers did need to get quite close! As there was a significant cost to any delay Mike Shewring and Dan Carrington (onsite ecologists for Natural Power Limited) and I agreed to install a nest-camera to monitor any disturbance so that operations could be go ahead but be instantly halted if the birds were disturbed. As the above clip shows, all progressed well and the single hatched chick fledged successfully last week.

Another part of the monitoring, being conducted in conjunction with the British Trust for Ornithology and Natural Power Limited, is using state-of-the-art GPS dataloggers to record the Nightjar's location to a high degree of accuracy at frequent intervals in order to study their foraging patterns. We tried this a few years ago using conventional radio-tags and it was almost impossible to keep track of the birds. These new tags record the bird's location to within 10m every 3 minutes!!! 

The downside is they cost about £350 each and you need to retrap the bird to get them back so that the data stored onboard can be downloaded. We have so far deployed 4 tags in South Wales and on the night of the 21st/22nd, on one of  my most successful Nightjar trapping sessions ever (7 birds - 4 new and 3 retraps), Mike and I recovered our first tag.

As the map above shows the bird in question didn't move very far in the 5 days the tag was recording but the results are, none-the-less, nothing short of amazing - effectively over 650 retraps in 5 days!!  There is a massive potential here to finally get to grips with exactly how these upland Nightjars cope with the vagaries of the Welsh weather and where exactly they go to find moths when it is doing what it often does in Wales - p***ing it down!!

Male Nightjar brooding two large young.  Photo © Steve Parr

Despite the awful summer we are having the Nightjars seem to be doing rather well. So far 11 chicks have fledged from 7 first brood nests and 4 of the females are currently back down on eggs so hopes are high that we can deploy and retrieve a few more tags yet.