par Corbera Serrajordia, Mireia 
Promoteur Jean, Hugé
Co-Promoteur Fessel, Birgit
Publication Non publié, 2024-08-29
Promoteur Jean, Hugé
Co-Promoteur Fessel, Birgit
Publication Non publié, 2024-08-29
Mémoire
| Résumé : | Avian nest usurpation and nest predation exert significant impacts on reproductive success, actingas potent selective forces shaping the evolution of nest defence behaviours. Furthermore, it canbecome a threat for the host population, in cases where the host species is vulnerable orendangered. This study focuses on the enemy recognition and nest defence strategies adopted bythe Green Warbler-finch Certhidea olivacea, an endemic passerine species to the GalapagosIslands whose population trends are currently decreasing. Invasive species, habitat degradationand increasing pressure from a potential usurper species (Small Ground-finch Geospiza fuliginosa)could be possible reasons that explain this trend. Bird mounts of the usurper (Small Ground-finch)and two different nest predators (Galapagos Barn Owl Tyto alba puncatissima and Smooth-billedAni Crotophaga Ani) were displayed to host nests during nest building and feeding phases. A cubethe size of the Small Ground-finch was used as control. Using various indicators (e.g., alarm calls,closest approach to dummy, community response) we found out that Green Warbler-finchesdisplay significantly different behaviours towards the different enemies, particularly against thepredators. The defence behaviour against the invasive Ani was significantly lower compared to theOwl. The reaction towards the potential nest usurper didn't significantly differ between nestingstages, and it was lower if compared to the predator's response. The preliminary bioacousticsanalysis of their alarm calls suggests conspecific cooperation against predators. Novel insights intothe nest defence mechanisms of the Green Warbler-finch are presented, highlighting theimportance of understanding these behaviours for future conservation efforts. |
