The aim of this study was to determine the habitat features affecting nest site selection and breeding success of the endangered Egyptian Vultures (Neophron percnopterus) breeding around the town of Beypazari. We searched and monitored nest sites in the study area (750 km2) for the years 2010 and 2011. The differences in terms of habitat features between nest sites and random points distributed along cliffs, and between successful and failed nest sites were investigated using both parametric approaches and machine learning methods with 21 habitat variables. The size of the Beypazari population of Egyptian Vultures was estimated to be 45 pairs. Seventeen nests in 2010 and 37 nests in 2011 were found and monitored. The breeding success of the population was estimated to be 100% in 2010 and 70% in 2011. Random Forests was the modeling technique with the highest accuracy and the modeling process chose 6 and 4 variables affecting nest site selection and breeding success of the species, respectively. Results showed that human impact was a potential factor governing the distribution of nest sites in the area and increased the probability of breeding failure as vultures clearly preferred to nest away from nearby villages, towns and roads, and nests on lower cliffs and nests that are close to the dump site (therefore the town center) was prone to failure. Utilization of elevation gradient and aspect showed trends similar to other populations of the species, with probability of nesting increasing at lower altitudes and for south facing cliffs. The overall results emphasize the potential conflict between human presence and the population of Egyptian Vultures in the area. Continuous monitoring of the nest sites and conservation activities towards raising public awareness are advised.

Pour limiter l'impact des activités humaines sur la biodiversité, les populations animales sont gérées dans de nombreux contextes. La gestion des populations animales comprend la conservation des espèces menacées, comme l’exploitation/régulation des espèces gibiers ou considérées nuisibles. Elle consiste à modifier la dynamique des populations soit en favorisant leur croissance, soit en réduisant leur abondance. Face à l’urgence d’agir dans un contexte de ressources financières limitées, une gestion efficiente des populations animales requiert une bonne compréhension de leur dynamique en réponse aux actions mises en œuvre. Durant mon doctorat, j’ai travaillé en partenariat avec des gestionnaires agissant sur deux systèmes biologiques : la conservation de rapaces méditerranéens (aigles de Bonelli et vautours percnoptères) et la régulation des densités de renards en paysage rural. Pour chaque système, mon travail a consisté i) en l’analyse des suivis de populations qui sont réalisés pour ii) évaluer l’effet de la gestion sur la dynamique des espèces gérées. Dans les deux contextes, j’ai pu iii) mettre en évidence la contribution de l’immigration à la croissance des populations menacées, comme à l’atténuation des effets de la régulation. Après iv) avoir extrait des recommandations pouvant améliorer l’efficience de la gestion en tenant compte de ces processus d’immigration, mon travail s’est conclu par v) une réflexion en retour sur l’optimisation des suivis de populations, afin qu’ils génèrent le plus d’informations pour un investissement moindre. Dans l’ensemble, ce travail aboutit à une réflexion sur les moyens favorisant une gestion efficiente des populations animales. / Due to the multiple interactions linking species together, human activities and animal species influence each other. Animal populations are therefore managed to favour long-term cohabitation. Wildlife management includes the conservation of endangered species, the harvest of game species and the control of species considered as pest. It consists in impacting population dynamics (density variation in a territory) either by favouring or limiting population growth. Faced with the complexity of ecological processes and the urgent need for acting in a context of decreasing allocated resources, an efficient management requires a precious understanding of population dynamics in response to actions. During my PhD, I collaborated with managers supervising two contrasted biological systems: the conservation of endangered Mediterranean raptors (Bonelli’s eagles and Egyptian vultures) and the control of fox densities in French rural landscapes. For each case of study, my work consisted in i) analysing data from population monitoring designed to ii) evaluate the management impact on population dynamics. In both systems, I highlighted iii) the crucial importance of immigration either in boosting endangered population or compensating for fox regulation. After having iv) derived concrete guidelines to improve management facing with immigration. I concluded my PhD by v) searching in turn for cost-effective designs of population monitoring. Overall, I questioned the contrasted systems I studied to understand pitfalls and solutions favouring an efficient management of animal populations.