Royal Netherlands Institute for Sea Research
Royal Netherlands
Institute for Sea Research

GPS bird tracking techniques

A 2 gram satellite transmitter with harnas, as applied on red knot. Photo: Rob Buiter


Advanced technologies in bird tracking with loggers and transmitters enable us to study behaviour of mobile animals such as birds on large scales in time and place. Technicians are continually working to reduce the size and increase the capabilities of avian satellite transmitters. Nowadays not only gulls are tracked, but even red knots. In general 3% of the weight of the bird is accepted as an upper limit for the weight of the tracker. The system includes a solar-powered, light-weight GPS tracker with rechargeable batteries, a tri-axial accelerometer, two-way data communication to a ground station network, automated data processing and visualisation in the Virtual Lab.

Trial study

In April 2016 -as part of a trial study-  a red knot (called Paula) was caught on the Dutch mudflats and equipped with a prototype satellite with a weight of only two grams. An average knot of 120 gram can easily carry it. The transmitter contains a very small but also very powerful solar panel, the battery is constantly charged in the Arctic summer.  Satellites then are able to generate a lot of high quality position data. The trial study learned that red knots, Calidris canutus islandica, are able to bridge huge distances in non-stop flihts without fuelling at suitable foraging ground. 

By means of Paula’s incredible high quality track, a couple of conjectures about red knot migration are confrimed. Based on radar observations on Greenland, and resightings of colour-ringed birds, there was quite a good idea about the migratory routines of red knots between the Wadden Sea and their breeding grounds in northeastern Canada. But this bird carrying the satellite transmitter clearly confirmed and visualized the ideas based on indirect observations and interpretations. (Interview Eva Kok and Theunis Piersma).

Satellite tracking occurs in close collaboration with UvA-BiTS (gulls, bar-tailed godwits, crab plovers), and Microwave Telemetry Inc. (red knots).

For technical specifications or other information, please contact Eva Kok by email (preferred). You will get a response as soon as possible. In urgent matters, you can contact her directly. 

T +31 (0) 222 452