Behavioral Ecology Advance Access originally published online on July 9, 2007
Behavioral Ecology 2007 18(5):811-821; doi:10.1093/beheco/arm052
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Sequential settlement and site dependence in a migratory raptor
a Department of Conservation Biology, Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, Avda. de María Luisa s/n., Pabellón del Perú, Apdo 1056, 41013 Seville, Spain b Department of Biology, University of Saskatchewan, S7NSE2, Canada
Address correspondence to F. Sergio. E-mail: fsergio{at}ebd.csic.es.
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Abstract |
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Habitat selection models, such as the ideal free, ideal despotic, site-dependent, and conspecific cuing models, are of great importance to behavioral ecologists given their capability to predict habitat distributions and to link individual behavior to population processes. However, there have been relatively few field tests of their predictions. We tested the 4 models by studying the process of sequential settlement on territory in 2 distant populations of a migratory raptor, the black kite Milvus migrans. Results were mainly consistent with the site-dependent model: on arrival, kites settled on progressively lower quality territories, and earlier arriving individuals were older, larger, and in better body condition than later arriving ones, leading to a state-dependent arrival sequence also predicted by a previous theoretical model of settlement pattern. Occupation of superior territories by superior phenotypes resulted in cascading advantages for earlier arriving individuals in terms of subsequent reproductive performance. At the population level, the populations expanded/retracted from lower quality sites during population increases/declines. The above scenario was consistent across the 2 populations, and a review of the literature uncovered a remarkably consistent picture of state-dependent arrival, progressive monopolization of best quality sites, and cascading effects on subsequent breeding performance. We propose as a general paradigm of sequential settlement the following process: 1) arrival date is a reliable surrogate of phenotype quality, 2) early-arriving individuals have preferential access to the best quality sites and partners, 3) the above conditions cascade into a number of benefits ultimately related to higher fitness for earlier arriving individuals.
Key words: arrival date, dominance, ideal despotic, individual quality, Milvus migrans, preemption, site dependence, territory quality.
Received 25 October 2006; revised 11 April 2007; accepted 15 April 2007.