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| Photo F. Sergio |
Congratulations Fabrizio, nice picture !
The Bloooooog!
Mostrando entradas con la etiqueta raptors. Mostrar todas las entradas
Mostrando entradas con la etiqueta raptors. Mostrar todas las entradas
lunes, 16 de noviembre de 2015
Check the cover !
Congratulations Fabrizio, nice picture !
lunes, 13 de julio de 2015
Award! Watson Raptor Prize 2015
The publication by Sergio et al. won the Watson Raptor Prize for the best publication on raptors of 2014. Congratulation to all (again) and thank to the Watson Birds Organization !!
jueves, 28 de mayo de 2015
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.
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.
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.
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| 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.
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