Taiga Bean Geese, sea Eagles & field workers

We can look back at the many successful HABITRACK field catches of waders, ducks, and geese during the spring and summer of 2024. For example, over 30 wigeon and pintails were tagged in the Netherlands, Finland, and France, with relatively high return rates in the autumn. Also, 18 pre-nesting and 4 moulting  Taiga Bean geese were successfully equipped with HABITRACK GPS tags in northern Finland.

However, a field action to tag individuals of the still relatively unknown Western population of Taiga Bean geese in Mecklenburg-Vorpommern (Germany) held serious challenges. Together with a Dutch goose catcher and his tame geese, a set of nets was set up at the beginning of November 2024 in an area with many wild geese enjoying the high-quality food of crop remains and grasslands.

On the first day, we could equip one goose with a GPS transmitter; on the second day, two geese; on the third day, three… That seemed a good start, and with a total fieldwork duration of 20 days, expectations became high as to the further development of these numbers. We were optimistic about obtaining a good sample size of tagged birds. But many white-tailed sea eagles resided around the catching area, probably feasting on the multitude of geese present only during this time of the year. As highly valued the present increase of sea eagle numbers is to conservationists (to whom we also count ourselves), in our catching setup, we were highly worried about the tame decoy geese, especially after an eagle tried a first attack at them on day 4.

From our studies, we know that geese are by no means stupid, precisely timing their migration to far-away weather conditions or reacting cautiously to various disturbances. But the cunningness of the sea eagles surprised us: After just a few days, they realized that we were attracting geese to the specific field and mistook it as us humbly presenting them with feeding opportunities. Plainly, after day 6, they did disturb any catching efforts, swooping down towards us, even injuring tame birds. We had to stop the field action prematurely. In total, five Taiga Bean geese were tagged in Mecklenburg-Vorpommern for the HABITRACK project.

Unfortunately, the bad luck did not end there. After only a few days, one of the transmitters sent repeated signals from the exact location and seemed stationary. Checking for it in the field, we retrieved it with shot pellets in the plastic cover. So, clearly, the bird had been shot, which is illegal in Germany. After another week, a second tag had to be retrieved, this time next to feathers left by an animal predator – most likely a sea eagle. The three remaining transmitters nicely show the movements of the birds, one even moving to the coast of the Baltic Sea. It remains to be seen if this will be the first tracked bird pointing towards mixing of the different populations of Taiga Bean geese in Scandinavia and Northern Germany.

Andrea Kölzsch for HABITRACK