The most important aims of this project are to link reproductive success of Barnacle Geese to their migration strategies and timing of migration and arrival. There we need to be able to successfully track spring migration of Barnacle Geese from their wintering grounds in the Netherlands to their breeding grounds in Arctic Russia.
The technology of tracking birds has advanced fast over the last decades, from overweight satellite transmitters to ultralight, solar powered GPS-trackers that are enable to send their data either via satellite, GSM network or bluetooth. The University of Amsterdam has developed one of the most state of the art devices, their UvA-BiTS logger, specially designed to track bird movements. Besides its ability to track and store a large number of GPS-fixes before sending this data via a type of bluetooth-network, this logger also has an accelerometer on board. This meter measures acceleration in 3 directions, making it possible to distinguish different behaviors of a bird. Flying will have an acceleration signal that is very different from sleeping, but also more subtle behaviors such as walking, preening or different types of foraging can be recognized.
As GPS-loggers are still rather heavy (the lightest devices with similar capabilities are now around 6g – fit for a large wader), one would need still smaller devices to track the smallest birds, migratory passerines. Already for years exists the geolocator, a device, now lighter than 1g, that measures light intensity and can thus track daylength. In combination with an internal clock and thus time of sunrise / sunset, one can determine the position of a bird on the globe at approximately 100 km precision.
We use both UvA-BiTS GPS-loggers and Intigeo geolocators to track Barnacle Geese. We use the larger GPS-loggers to precisely determine migration timing but also behavior of geese along the flyway and precise movements on the breeding grounds. These loggers collect detailed data which are the tracks you will occasionally see on this website. With the smaller geolocators attached on leg colourbands we can track migration strategies, but these also enable to determine whether the larger GPS-loggers have any detrimental effect on migration speed of the geese, by comparing migration timing as tracked by GPS-loggers and geolocators.
Some first results show an interesting divergence in migration strategies, animated below.