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Article Dans Une Revue Auk Année : 2010

Determinants of Territorial Recruitment in Bonelli's Eagle ( Aquila fasciata ) Populations

Determinantes del Reclutamiento Territorial en Poblaciones de Aquila fasciata

Résumé

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 agespecific 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.
Resumen.-El reclutamiento es un componente esencial de la historia de vida y de la dinámica poblacional en las aves. En el presente estudio se proporciona información detallada sobre los factores que determinan el reclutamiento territorial en una especie amenazada: Aquila fasciata. Se estudiaron dos poblaciones localizadas en el extremo noroccidental de la distribución de la especie, una en Cataluña (NE de España) y la otra en Provence y Languedoc-Roussillon (SE de Francia). La metodología de campo se basó en un estudio a largo plazo que incluyó marcaje de volantones (n = 451 pollos) y seguimiento de territorios en ambas poblaciones durante el período comprendido entre 1980 y 2007. En primer lugar, se estimó una tasa de retorno global del 9.97 % (45 reclutas), que no difirió significativamente entre las poblaciones estudiadas. En segundo lugar, se detectaron efectos significativos del año de nacimiento y del éxito reproductor del territorio de origen sobre la probabilidad de que un volantón fuera posteriormente reclutado: aquellos pollos de territorios con mayor éxito mostraron mayor probabilidad de reclutamiento. En tercer lugar, se utilizaron técnicas de captura-reavistamiento para estimar la probabilidad de que un individuo territorial de una determinada edad fuera un recluta. Este parámetro mostró valores entre 0.985 y 0.999 para individuos de dos años, entre 0.763 y 0.808 para individuos de tres años, y se redujo drásticamente para individuos de cuatro años o mayores, mostrando valores de ente 0.066 y 0.272. En cuarto lugar, las hembras se dispersaron a mayor distancia que los machos. Además, las hembras de Cataluña se dispersaron a mayor distancia que las hembras de Francia. En último lugar, aquellos territorios previamente ocupados, situados en áreas con elevada densidad y situados en áreas de mayor calidad se mostraron más atractivos para individuos sin experiencia territorial previa. Abstract.-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.

Dates et versions

hal-02126324 , version 1 (11-05-2019)

Identifiants

Citer

Antonio Hernández-Matías, Joan Real, Roger Pradel, Alain Ravayrol, Nicolas Vincent-Martin, et al.. Determinants of Territorial Recruitment in Bonelli's Eagle ( Aquila fasciata ) Populations. Auk, 2010, 127 (1), pp.173-184. ⟨10.1525/auk.2009.09143⟩. ⟨hal-02126324⟩
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