Urszula Zaremba, Angelika Zbieć, Zbigniew Kasprzykowski
Ornis Polonica 2019, 60: 40–46
https://doi.org/10.12657/ornis.2019.1.2
Abstract: Observations of kleptoparasitism by Jackdaws Corvus monedula and Rooks C. frugilegus were performed in autumn-winter 2015–2016 on the outskirts of Siedlce. A total of 259 cases of kleptoparasitism were recorded: walnuts that had been collected by Rooks were taken over by other Rooks or Jackdaws. Rooks were involved in 160 interactions (61.8%) and Jackdaws in 83 (32.0%), while both species attacked Rooks with food in 16 cases (6.2%). The number of individuals in a group of agressors did not differ between the two species. A total of 16.2% of Rook kleptoparasitic attempts were successful, while Jackdaws succeeded in only 7.2% cases. The success of kleptoparasitic attempt was significantly related to the size of a mobbing party in the Rook, but not in the Jackdaw.
Keywords: Common Walnut Juglans regia, competition for food, interspecific interactions, Jackdaw, Rook
