Master’s degree project in Animal Ecology at the GEP

Jaume Badia is joining the GEP for his Master’s degree project in Animal Ecology at the University of Lund, Sweden. Jaume work will focus on the conservation maeasures to protect the Egyptian Vulture at Fuerteventura (Canary Islands) under the direction of Ana Sanz-Aguilar and in collaboration with the Estacion Biologica e Doñana (CSIC).

New publication on Egyptian vulture demographic parameters!

Sanz-Aguilar, A., Cortés-Avizanda, A., Serrano, D., Blanco, G., Ceballos, O., Grande, J.M., Tella, J.L., Donázar, J.A.: Sex- and age-dependent patterns of survival and breeding success in a long-lived endangered avian scavenger. Scientific Report, 7 2017 Article number 40204, doi: 10.1038/srep40204

 Abstract. In long-lived species, the age-, stage- and/or sex-dependent patterns of survival and reproduction determine the evolution of life history strategies, the shape of the reproductive value, and ultimately population dynamics. We evaluate the combined effects of age and sex in recruitment, breeder survival and breeding success of the globally endangered Egyptian vulture (Neophron percnopterus), using 31-years of exhaustive data on marked individuals in Spain. 

Photo: J. Bas

Mean age of first reproduction was 7-yrs for both sexes, but females showed an earlier median and a larger variance than males. We found an age-related improvement in breeding success at the population level responding to the selective appearance and disappearance of phenotypes of different quality but unrelated to within-individual aging effects. Old males (≥8 yrs) showed a higher survival than both young males (≤7 yrs) and females, these later in turn not showing aging effects. Evolutionary trade-offs between age of recruitment and fitness (probably related to costs of territory acquisition and defense) as well as human-related mortality may explain these findings. Sex- and age-related differences in foraging strategies and susceptibility to toxics could be behind the relatively low survival of females and young males, adding a new concern for the conservation of this endangered species.

New publication on Raptors on Islands

Sanz-Aguilar A, de Pablo F, Donázar JA. Age-dependent survival of island vs. mainland populations of two avianscavengers: delving into migration costs. Oecologia, in press (doi:10.1007/s00442-015-3355-x) 

Abstract: Large terrestrial long-lived birds (including raptors) are typically sedentary on islands, even when they are migratory on the mainland. Density-dependent variation in the age at first breeding has been described as responsible for the long-term persistence of long-lived bird populations on islands. However, sedentary island populations may also benefit from higher survival rates derived from the absence of migration costs, especially for young individuals. Thus, sedentary island populations can mimic a natural experiment to study migration costs. 

Photo: Felix de Pablo

We estimated the age-dependent survival of two sedentary raptors on Menorca Island (Egyptian vultures Neophron percnopterus and red kites Milvus milvus) and compared these estimates with those reported for other migratory and sedentary populations. In Menorca, Egyptian vultures, but not red kites, showed low levels of human-related mortality resulting in extremely high survival probabilities, probably due to different diet choices and behavioral patterns. Juvenile Egyptian vultures and red kites in the studied population had lower survival probabilities than adults. This difference, however, was smaller than those reported for mainland migrant populations, which showed a lower juvenile survival rate. In fact, between-population comparisons suggested that survival of the young in migrant populations may be triggered by mortality factors in wintering areas. In contrast, adult survival may respond to mortality factors in breeding areas. Our results suggest that raptor species that become sedentary on islands may benefit from higher pre-breeder survival prospects in comparison with their mainland migrant counterparts. This fact, in combination with an earlier age at first reproduction, may facilitate their persistence.

New publication on Egyptian vulture!

Sanz-Aguilar A, Sánchez-Zapata JA, Carrete M, Benítez JR, Ávila E, Arenas R & Donázar JA. 2015. Action on multiple fronts, illegal poisoning and wind farm planning, is required to reverse the decline of the Egyptian vulture in Southern Spain. Biological Conservation  187:10-18.

Abstract: Large body-sized avian scavengers, including the Egyptian vulture (Neophron percnopterus), are globally threatened due to human-related mortality so guidelines quantifying the efficacy of different management approaches are urgently needed. We used 14 years of territory and individual-based data on a small and geographically isolated Spanish population to estimate survival, recruitment and breeding success. We then forecasted their population viability under current vital rates and under management scenarios that mitigated the main sources of non-natural mortality at breeding grounds (fatalities from wind farms and illegal poisoning).

Photo: A. Atienza

Mean breeding success was 0.68 (SD=0.17) under current conditions. Annual probabilities of survival were 0.72 (SE=0.06) for fledglings and 2 yr old non-breeders, 0.73 (SE=0.04) for non-breeders older than 2 yrs old and 0.93 (SE=0.04) for breeders. Probabilities of recruitment were 0 for birds aged 1 to 4, 0.10 (SE=0.06) for birds aged 5 and 0.19 (SE=0.09) for older birds. Population viability analyses estimated an annual decline of 3-4% of the breeding population under current conditions. Our results indicate that only by combining different management actions in the breeding area, especially by removing the most important causes of human-related mortality (poisoning and collisions on wind farms), will the population grow and persist in the long term. Reinforcement with captive breeding may also have positive effects but only in combination with the reduction in causes of non-natural mortality. These results, although obtained for a focal species, may be applicable to other endangered populations of long-lived avian scavengers inhabiting southern Europe.