title: Saving the best for last: Differential usage of impaled prey by red-backed shrike (Lanius collurio) during the breeding season.
abstract: 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.
authors.affiliation: 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. Electronic address: fmorellius@gmail.com.
authors.forename: Federico
authors.initials: F
authors.lastname: Morelli
authors.affiliation: 22 Rue des Roses, 87200 Chaillac-sur-Vienne, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Bussière
authors.affiliation: Siedlce University of Natural Sciences and Humanities, Faculty of Natural Science, Department of Zoology, Prusa 12, 08-110 Siedlce, Poland.
authors.forename: Artur
authors.initials: A
authors.lastname: Goławski
authors.affiliation: Institute of Zoology, Poznan University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznań, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Tryjanowski
authors.affiliation: P.O. Box 272, Eilat 88000, Israel.
authors.forename: Reuven
authors.initials: R
authors.lastname: Yosef
mesh_terms: D000818:Animals; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D008297:Male; D009425:Nesting Behavior / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000502:physiology*; D020308:Songbirds / Q000502:physiology*
keywords: Breeding stage; Food resource; Laniidae; Larder; Prey item