During two weeks of September 2012 we trying a new ornithodolite system to track birds on south-eastern Öland. An ornithodolite is a range finder, in this case a Vector 21 Aero, which is a pairs of 7x42 binoculars equipped with a laser range finder, and sensors for azimuth and elevation angles. The Vector is sending data directly to a PC. Simultaneous measurements of the wind are obtained from an ultrasonic anemometer, placed on a 3 m high pole, which sends data every second via a radio link to the same PC. For wind recording at higher altitudes we track balloons with the Vector to achieve wind profiles at the altitudes where birds are flying. The weather has been perfect for fieldwork and we have been able to test the system under field conditions, and changed some procedures to work optimally.
The selection of a site along the coast of Öland is based on the fact that many migrants pass there on autumn migration, and the birds are able to use the coastline to compensate for the effect of cross-winds. The system allows us to track birds and flocks that are within 2 km form the observer, and often we obtain very long tracks that can be plotted in google earth maps. So far, we have mainly managed to track flocks of geese, ducks and waders (such as bar-tailed godwit, below),
but even passerines can be tracked if they fly directly towards or away from the observer. As we now have a working system this opens up a great number of opportunities to test different predictions about flight behaviour. We have also enjoyed the bird life during migration on Öland, and among others we have seen a red-footed falcon, several peregrines, and a lesser spotted eagle, in addition to the regular migrants.
During the field season of 2012 the team has been Prof. Colin Pennycuick, University of Bristol, Susanne Åkesson and Anders Hedenström, CAnMove, LU.
|Prof. Colin Pennycuick, University of Bristol|