Abstract
The greater horseshoe bat is an insectivorous bat species that maintains a close proximity to humans, including the choice of its roosts and foraging areas. In 2016, this bat species was listed as Vulnerable on the regional red list of the former Poitou-Charentes region following the observation of a decline in the last fifteen years. In this context, the aim of this thesis is to describe the biology of the greater horseshoe bat populations and to understand the influence of the landscape on their functioning. Specifically, it involves i) analyzing if the landscape can limit gene flow between populations, ii) identifying potential vulnerable populations, and iii) determining, from the prey spectrum of the greater horseshoe bat, the landscapes to be preserved as a priority to preserve the key resources of this species. First, the population genetic approach showed the existence of a large stable population with high genetic diversity from France to the south-west of the Pyrenees (Spain). A weak pattern of isolation by distance between these colonies and strong coefficients of relatedness between very distant individuals underline the great ability of the greater horseshoe bat to move. However, the colonies at the north of the range show lower genetic diversity and greater genetic differentiation with the other colonies, suggesting that these northern colonies are more vulnerable to extinction. Then, we developed a molecular approach to study the diet from guanos that allows a simultaneous identification of the bat species and its prey - without penalizing the amplification of the prey by an over-amplification of the predator - from guano samples. Our comparative multicriteria analyzes of primers sets enabled us to determine the optimal protocol for studying the diet of insectivorous bats according to the type of sampling, the type of colony studied and the logistical constraints. Finally, our sampling of seven colonies throughout the maternity season showed that the greater horseshoe bat feeds on much more diverse prey than expected from the literature, but that the majority of these are poorly occurrents. Diversity analyzes reveal a high plasticity of diet strategies according to the quality of the surrounding landscape, the phenology of the prey, and the energetic needs of the greater horseshoe bat. The most commonly detected prey species are associated with the presence of permanent hedgerows and grasslands, and some with woodlands. These elements of the landscape are therefore primarily to conserve, not only to maintain connectivity between colonies and foraging areas, but also to preserve the key resources of the greater horseshoe bat. In conclusion, this thesis made it possible to define suitable conservation units that take into account genetic processes. Although the landscape does not appear to limit breeding dispersal in this species, some landscape features strongly affect the diet of greater horseshoe bat and should be considered in conservation strategies.