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Why offspring delay dispersal: experimental evidence for a role of parental tolerance
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology.
2002 In: Proceedings of the Royal Society of London, Series B, Vol. 269, 1709-1713 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2002. Vol. 269, 1709-1713 p.
URN: urn:nbn:se:uu:diva-90285OAI: oai:DiVA.org:uu-90285DiVA: diva2:162588
Available from: 2003-04-03 Created: 2003-04-03Bibliographically approved
In thesis
1. The Nepotistic Parent; Predator Protection, Kinship and Philopatry
Open this publication in new window or tab >>The Nepotistic Parent; Predator Protection, Kinship and Philopatry
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Evolution is fuelled by independent reproduction events. Yet, the offspring of at least three percent of all bird species postpone dispersal and forego independent reproduction. The Siberian jay, Perisoreus infaustus, is such a species where some offspring are philopatric and remain in their natal territory for up to three years, forming family groups. The main finding of this thesis is that nepotistic anti-predator behaviour displayed by parents provided philopatric offspring benefits, which could be an incentive to stay and forego independent reproduction. Predation, (hawks - 80 % and owls - 15% of deaths observed) is the main cause of mortality. Parents increased their vigilance nepotistically; they were more vigilant against surprise predator attacks, and gave alarm calls when attacked when feeding together with offspring. However, the two parents differed in their behaviour. Mothers gave calls only when together with their offspring, while males also warned unrelated immigrants. Sitting predators were approached and mobbed more intensely by parents in the presence of philopatric offspring. The vocalisation of Siberian jays provides information about predation risk. Specific calls are given for hawks and owls, and calls also varied with hawk behaviour. The nepotistic anti-predator behaviour of parents is a benefit, which the offspring can gain only “at home”, and such behaviour appears to promote offspring to forego dispersal and independent reproduction. This was confirmed in an experimental manipulation; philopatric offspring dispersed when fathers were removed and replaced by a despotic, immigrant stepfather. From a life-history perspective, parents have an incentive to protect their reproductive investment. Nepotistic anti-predator behaviour create a safe haven in the natal territory for philopatric offspring and provides direct fitness benefits. Without such direct fitness benefits offspring may disperse and wait for a breeding opening elsewhere.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 38 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 824
Biology, referential alarm calls, delayed dispersal, nepotism, vigilance, alarm calling, mobbing, extended parental care, families, Perisoreus infaustus, Siberian jay, Biologi
National Category
Biological Sciences
Research subject
Population Biology
urn:nbn:se:uu:diva-3384 (URN)91-554-5575-1 (ISBN)
Public defence
2003-04-29, Ekmanssalen, EBC, Uppsala, 10:00
Available from: 2003-04-03 Created: 2003-04-03Bibliographically approved

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