Foerageergedrag van Rode Wouwen Milvus milvus in Duitse akkergebieden

On a nest in the eastern Netherlands, two of three Red Kite chicks were equipped with a GPS-transmitter in 2022. One of the juveniles started its post-fledging dispersal when 67 days old (on 27 July). Between 29 July and 4 August it worked its way eastwards towards Dannenberg near the river Elbe (distance 295 km) where it remained for 32 days till 5 September. This bird was observed in its temporary stopover on 3 and 4 September. The region is mostly farmland, dominated by rapeseed, maize and cereals both north and south of the Elbe. Harvested fields of rapeseed and cereals were favoured by the local assembly of 65 Red Kites, whereas unharvested fields of maize and hayfields were largely avoided. The harvested fields were lightly cultivated in August and September, and attracted many Red Kites, among which the GPS-carrying juvenile from The Netherlands. Inspection of the fields showed that vole density must have been low: 0.08 burrows/m² on average in rapeseed, 0/m² in cereal stubble and 0.28/m² in ungrazed grassland. The latter field was the only one where the GPS-kite returned to forage on two consecutive days. Red Kites followed the cultivation of arable land, where they foraged on earthworms that had become exposed. At least six full-grown kites captured on average 7.5 earthworms/min (199 catches, 1582 sec), the only juvenile 4.0/min (3 catches, 45 sec). Of all prey taken, 53% was too small to be identified, 3% consisted of large earthworms and 45% of small ones. All prey was taken whilst walking or sitting on the ground. It is surmised that the scarcity of voles forced the kites to forage on earthworms, which became available in this particular region where harvest was followed by light cultivation in August and September. The earthworm bonanza was also harvested by a multitude of Starlings and Lapwings, and some Herring Gulls and Buzzards.