Raymond Klaassen, Adri Clements, Kjell Janssens & Henk Beckers (2025) Home range size and habitat use of Eurasian Hobbies Falco subbuteo in a Dutch agricultural landscape. LIMOSA 98 (3): 101-116.

Four adult Eurasian Hobbies were tagged in 2021-23 with GPS-loggers to study home range size and habitat use in an agricultural landscape in the Dutch province of Limburg. Three birds provided sufficient data for analysis, one female (tracked for 37 days) and two males (tracked for 11 and 53 days). The female (Jacoba, 2021) generally remained near the nest (90% of all positions within 600 m from the nest) and ranged only occasionally up to about 8 km from the nest. The first male (Thei, 2021) used a larger area (90% of all positions within 2 km from the nest), with maximum distances of 9 km from the nest. The second male (Lex, 2023) also used a larger area than the female (90% of all positions within 3.2 km from the nest), and ranged up to 11.4 km from the nest. Our results suggest that the home range size of Hobbies is relatively large compared to the similarly sized Common Kestrel Falco tinnunculus, and more comparable to other wideranges species such as Honey Buzzard Pernis aviporus and Montagu’s Harrier Circus pygargus. For the habitat use, the categories ‘trees and forest’ and ‘grassland’ stood out. These were also the two main common habitat types in the area. For Lex, exceptionally much data was obtained (13 363 GPS positions in total), which allowed a more detailed habitat use analysis. For example, for this bird we could distinguish between flying and stationary positions (based on the instantaneous speed). This showed a preference for ‘trees and forest’ for stationary positions and a preference for ‘grassland’ for flying positions. By using the Dutch tree database (bomenregister.nl), we could show that Lex was mainly using relatively large trees such as Aspen Populus sp., probably as watch points for hunting. For the flying positions also a preference for the categories ‘Other’, ‘Roads’ and ‘Buildings’ was noted. This turned out to be related to the bird hunting near dairy farmyards. The preference for grasslands and farmyards reflects the diet of the Hobbies in the study area that mainly consist of birds such as swallows Hirundinidae, and sparrows Passer sp. In the varied agricultural landscape of the Dutch river Maas valley, Hobbies have notably large home ranges. The question is whether this is a natural aspect of their aerial lifestyle, or whether a large home range is a sign of (too) low prey population densities. Conservation measures such as Nature 2000-areas and Agri-Environment Schemes do not seem particularly important for foraging Hobbies, thus the conservation of the enigmatic species in agricultural landscapes seems to depend in the first place on the conservation of common bird prey species.

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