Eagles research in Poland: history in the making

We have managed to fit an eagle with a data logger for the very first time in Poland. The procedure was a success and the patient – an adult male of Lesser Spotted Eagle – is feeling well.

While feeding its chick, it provides us with data regarding its hunting sites and its habitat preferences.

A data logger is a device which registers its position at a regular cycle in time. The position is established using the Global Positioning System and is then sent to us via a mobile telephony system.

This method has been introduced in nature conservation only in the recent years. Previously the large size of these devices made it impossible to fit on a bird. However technological advances in the last years have allowed this appliance to be used on birds without any real interference or disruption of their normal behaviour. This method is almost revolutionary as the only alternative to the use of data loggers are field observations using spotting scopes and binoculars. However in the case of such efficient fliers as eagles, these traditional methods could not provide any satisfactory results.

Although our project is concerned with Greater Spotted Eagle, there was a reason why a data logger was fitted to a Lesser Spotted Eagle. One of the tasks within our project is to establish the degree of hybridisation, i.e. mixing of the two species: Greater Spotted Eagle and Lesser Spotted Eagle. Data retrieved with the help of the data logger fitted today will enable us to define differences in these eagle’s hunting and nesting areas.

When fitting the bird with the data logger, we took the eagle’s measurements and weight and also ringed it with colour rings. These ensure easy identification in the field by not just professional ornithologists but also by any keen birdwatcher using reasonable optical equipment. Our male has a yellow and white ring marked with number 59.