We compared the prey composition of the red-backed shrike's (Lanius collurio) larders in agricultural habitats in Italy, France and Poland. This species exhibits the behaviour of impaling prey in larders, a behaviour attributed not only to storing food, but also as a social indication for sexual selection and/or demarcation of territories. A total of 426 impaled items were identified in 244 larders. Most common prey were identified for each country: Insecta (Hymenoptera) in Italy, Amphibia, Insecta (Diptera) and Clitellata in Poland, and Insecta (Orthoptera, Lepidoptera) in France. We found no relationship between type of prey impaled and height of impalement, however, we noted a negative relationship between the height of impalement and the distance to the nearest road. Furthermore, impaled toxic prey were found in all three countries, strengthening the possibility that prey are exposed to expedite the degradation of toxins or used as a social signal. Our results showed that the average weight of impaled prey was greater during the last reproductive stage (hatching and feeding young), providing evidence of differential usage of impaled prey during the breeding season. We therefore hypothesize that larger animals provide more energy, then vertebrates are preferred to invertebrates, especially when parents are feeding their nestlings.

Faculty of Biological Sciences University of Zielona Góra Institute of Biotechnology and Environment Protection Prof Szafran St 1 PL 65 516 Zielona Góra Poland; Czech University of Life Sciences Prague Faculty of Environmental Sciences Department of Applied Geoinformatics and Spatial Planning Kamýcká 129 165 00 Prague 6 Czech Republic

Institute of Zoology Poznan University of Life Sciences Wojska Polskiego 71C 60 625 Poznań Poland

P O Box 272 Eilat 88000 Israel

Rue des Roses 87200 Chaillac sur Vienne France

Siedlce University of Natural Sciences and Humanities Faculty of Natural Science Department of Zoology Prusa 12 08 110 Siedlce Poland

Citace poskytuje Crossref.org

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