Behaviour 2019
Take the risk: nest building in threatening sites by a bird
Katherine Porras-Brenes1,2, Jorge M. De la O1,2, Sabrina Amador-Vargas1. 1Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá, Panama; 2Escuela de Ciencias Biológicas, Universidad Nacional, Heredia, Heredia, Costa Rica

In the tropics, egg predation on bird nests is a strong selective pressure on reproductive success. Birds have adopted certain strategies to increase nest survival, such as nesting near wasp nests or in swollen-thorn acacia trees, well-known for the aggressive defense of Pseudomyrmex ants. There are anecdotal reports in the literature about the great kiskadee (Pitangus sulphuratus) nesting on acacia trees, but the extent of this behavior is still unknown. The aims of this study were to evaluate the use of acacia trees by P. sulphuratus in a dry forest of Costa Rica, to test for a preference by ant-defended trees, and to identify differences in nesting sites between protected areas and nearby non-protected areas. We documented a surprising use of acacia trees by the great kiskadee, and the use of other threatening artificial sites, which may minimize the offspring mortality and could even be dangerous for the adults. Probably P. sulphuratus individuals have learned to choose places that may hurt predators, especially mammals and snakes. Hence, birds may have also developed techniques to prevent self-damage, which could be investigated further.