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1 January 2010 Determinants of Territorial Recruitment in Bonelli's Eagle (Aquila fasciata) Populations
Antonio Hernández-Matías, Joan Real, Roger Pradel, Alain Ravayrol, Nicolas Vincent-Martin, Fabrice Bosca, Gilles Cheylan
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Recruitment is an essential component of the life history and population dynamics of bird species. We provide comprehensive information on the determinants of territorial recruitment in populations of the endangered Bonelli's Eagle (Aquila fasciata). Field work was based on a long-term study of two populations located in the northwest of this species' range, one in Catalonia (northeastern Spain) and the other in Provence and Languedoc-Roussillon (southeastern France). Nestlings were banded (n = 451 marked birds) and known territories were intensively monitored during the period 1980–2007. First, a global return rate of 9.97% (45 recruits) was calculated, with no significant differences between the two populations. Second, results showed that both the birth year and the breeding success of the birth territory had significant effects on recruitment probability: nestlings from territories with better breeding success were more likely to recruit. Third, seniority analyses based on capture—resighting techniques were used to estimate the age-specific probabilities that a territorial bird in a given year was inexperienced. The parameter estimates for this probability ranged from 0.985 to 0.999 for 2-year-olds and from 0.763 to 0.808 for 3-year-olds and then fell drastically to 0.066–0.272 for 4-year-olds and older. Fourth, females were found to disperse farther than males. Additionally, there was a significant interaction between sex and area of birth, in that females from Catalonia dispersed farther than females from France. Finally, previously occupied territories located in the highest-quality areas with the highest territorial density were found to be the most attractive to inexperienced individuals.

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Antonio Hernández-Matías, Joan Real, Roger Pradel, Alain Ravayrol, Nicolas Vincent-Martin, Fabrice Bosca, and Gilles Cheylan "Determinants of Territorial Recruitment in Bonelli's Eagle (Aquila fasciata) Populations," The Auk 127(1), 173-184, (1 January 2010).
Received: 19 January 2009; Accepted: 1 May 2009; Published: 1 January 2010
Aquila fasciata
Bonelli's Eagle
Hieraaetus fasciatus
natal dispersal
seniority probability
territory selection
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