Suchergebnisse

In natural conditions, Griffon Vultures typically show shy behaviour and escape by flying if approached by humans. According to the state-dependent foraging theory, Griffon Vultures should modify their foraging behaviour depending on food availability and predation risk, humans being the main potential predator. We tested the Reaction Time (RT) and Flight Initiation Distance (FID) in five different artificial feeding schemes over three years in which food availability in the field varied significantly. The first scenario was set in a so-called "vulture restaurant", in which government employees feed vultures that may exhibit tame behaviour and stay within a few meters from a feeding person. Scenario 2 involved similar conditions, but here the researchers not employees placed the food in the vulture restaurant. The vultures did not land at the restaurant until one day had passed, and they flew away when people approached them within 250 m. The third scenario was established in a local zoo several months after the closure of the vulture restaurant. Here, employees fed captive vultures that were often accompanied by wild birds that landed to take food. The RT was 14.2 min and the FID was 50 m. The fourth scenario was established during the subsequent breeding season in a mountain where vultures were fed by the authors of the present study. The RT was 2.8 min and the FID was 15.2 m. The fifth scenario was established in another mountain after the breeding season. Now, the RT was 19.2 min and the FID was 52.2 m. These results demonstrate the ability of vultures to evaluate the predation risk depending on food availability and their state of hunger, and their ability to modify their behaviour from "natural" caution ("shyness") towards a more tolerant ("fearless") behaviour. ; Peer reviewed

We analyse the reply by Suárez et al. (2003) to our previous paper (Martínez et al., 2003), concluding that both reached the same general conclusion. The low quality of studies and evaluations of environmental impact assessment on birds is mostly due to a lack of interest and political will for using the information available and for detecting and solving relevant gaps in our knowledge. For this reason, the regulation of the Environmental Impact Assessment of projects is not applied efficiently in Spain. We also conclude that the disagreements between both papers refer mostly to details on (1) the relevance of gaps in basic information, (2) methods for using such information and (3) proposals to improve the quality of studies and evaluations. There are gaps in basic information, but a proper use of available sources which are seldom used would improve significantly studies and evaluations in the short term. Such sources are scientific papers on the biology of bird species and reports on the results of monitoring programs of the efficiency of correction measures of previous impacts. Increasing the scientific skills of technicians would improve the efficient use of these sources of information. Finally, the development of a variety of methods for the control of the quality of studies and evaluations, as well as of some regulations seldom used such as Territory Planning and Strategic Environmental Assessment, would further contribute to solve its general low quality. ; Peer Reviewed

Natal dispersal, the movement between the birth and the first breeding site, has been rarely studied in long-lived territorial birds with a long-lasting pre-breeding stage. Here we benefited from the long-term monitoring programs of six populations of Egyptian vultures (Neophron percnopterus) from Spain and France to study how the rearing environment determines dispersal. For 124 vultures, we recorded a median dispersal distance of 48 km (range 0–656 km). Linear models were used to assess the effect of population and individual traits on dispersal distance at two spatial scales. Dispersal distances were inversely related to vulture density in the natal population, suggesting that birds perceive the abundance of conspecifics as a signal of habitat quality. This was particularly true for declining populations, so increasing levels of opportunistic philopatry seemed to arise in high density contexts as a consequence of vacancies created by human-induced adult mortality. Females dispersed further than males, but males were more sensitive to the social environment, indicating different dispersal tactics. Both sexes were affected by different individual attributes simultaneously and interactively with this social context. These results highlight that complex phenotype-by-environment interactions should be considered for advancing our understanding of dispersal dynamics in long-lived organisms. ; Funds were partially provided by Diputación General de Aragón, Junta de Andalucía, Comunidad de Bardenas and Projects CGL2009-12753-C02-02, CGL2009-12753-C02-01/BOS and CGL2010-15726 of Spanish Ministerio of Economía y Competitividad. ACA was supported by a contract Juan de la Cierva Incorporación (IJCI-2014-20744; Ministerio de Economía y Competitividad, Spain) and a Post-Doc contract Programa Viçent Mut of Govern Balear, Spain (PD/039/2017). EA was supported by La Caixa-Severo Ochoa International PhD Program 2015, JM was supported by a Basque Government predoctoral fellowship PRE_2018_2_0112 (2017). ; Peer reviewed