The presence of kleptoparasitic fledglings is associated with a reduced breeding success in the host family in the barn owl

Motti Charter, Ido Izhaki, Alexandre Roulin

Research output: Contribution to journalArticlepeer-review


Fledgling birds sometimes abandon their own nest and move to neighboring nests where they are fed by host parents. This behaviour, referred to as ‘nest-switching’, is well known in precocial birds that are mobile soon after hatching and can easily reach foster nests. In contrast, due to the difficulty of observing nest-switching in territorial altricial birds, the causes and consequences of moving to others’ nests are poorly known in this group of birds. Nest-switchers can be adopted by the foster parents or they can steal food from the host parents meant for their offspring, a form of kleptoparasitism, which may result in reduced breeding success of the host nest. In Israel, 12 barn owl fledglings left their natal nests and were found in 9 host nests out of 111 monitored nests (8.1%). Nest-switchers that fledged earlier in the breeding season flew shorter distances to reach host nests probably because the density of nests with younger nestlings is higher early in the season. The number of host nestlings fledged and the percentage of nestlings fledged was lower in host nests than in nests without switchers. The occasional nest-switchers were always older than host nestlings (respectively 80 and 50 days of age, on average) and host parents fledged fewer young when nest-switchers occupied host nests with younger nestlings. This suggests that nest-switchers are kleptoparasites because the presence of the older alien fledglings is associated with a lower breeding success of the host parents.

Original languageEnglish
Article numbere01770
JournalJournal of Avian Biology
Issue number7
StatePublished - Jul 2018

Bibliographical note

Funding Information:
Acknowledgements – We give special thanks to Yossi Leshem for logistical help, Kobi Meyrom for assistance in field work. We thank Marek Kouba and Jan-Åke Nilsson for excellent suggestions on an earlier draft. Funding – This work was funded by Univ. of Lausanne.

Publisher Copyright:
© 2018 The Authors


  • barn owls
  • host nests
  • kleptoparasite
  • nest-switching
  • parasitism

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology


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