Tijdelijke aansluiting van jonge Rode Wouwen Milvus milvus na het uitvliegen bij andere Rode Wouwen en Haviken Accipiter gentilis

Ruiter R. de, van Rijn S. & Bijlsma R.G. 2024. Young Red Kites Milvus milvus visiting active nests of congeners and Goshawk Accipiter gentilis in the postfledging period. De Takkeling 32: 79-87. Nest switching during the post-fledging period was recorded in three out of twelve Red Kites from The Netherlands equipped with GPS-GSM logger in 2023. A 70 days old fledgling from a nest with three chicks moved in a northeasterly direction to another Red Kite nest with two fledglings 4.5 km away (a nest that hitherto had not been known to the local raptorphiles, despite several observations in early spring). It stayed there for 12 hours, including roosting at night, before it returned to its natal site. The same fledgling was registered roosting some 900 m away from another nest of Red Kite at 6.3 km from the natal site, when it was 78-79 days old; the oldest chick of this nest was three days younger than the visiting fledgling. Similarly, a fledgling from a nest in Drenthe stayed at another Red Kite nest 54 km away between 30 July and 8 August, when 86-95 days old. It was 8 days older than the oldest chick of the nest to which it had switched. And in southern Limburg a fledgling with a GPS-logger switched to another Red Kite nest 6.0 km away on 30 July (when 84 days old), where it remained from 16 to 19 August. The visiting bird was 9 days older than the oldest fledgling of the visited nest. A probable case of interspecific nest switching was recorded once, i.e. on 20 July 2020, when a Red Kite fledgling moved from its natal site in Twente to the forested region of the Veluwe near Staverden, 88 km away from the natal site. Upon checking the latter site, begging fledglings of Goshawks Accipiter gentilis were heard in a tall stand of douglas fir Pseudotsuga menziesii, with the Red Kite in close attendance for 24 hours. The young kite was then seen leaving the Goshawk site in an easterly direction. Checking the data retrieved from the GPS-logger it turned out that after its departure the bird had flown back in a straight line to Twente, the region where is was born. It is suggested that the loud begging-calls of the Goshawk fledglings may have attracted the young kite during its post-fledging dispersal. Exploratory behaviour after fledging is thought to be beneficial when in later life decisions should be taken where to settle as a breeding bird. In the short term a fledgling may profit from nest-switching by being fed for slightly longer than at its own nesting site, especially regarding the fact that fledglings of the visited nest were always younger than the interloper.