The endangered state of H. atrimaxillaris is of concern to conservation due to its restricted and increasingly fragmented range on the Osa peninsula. The differentiation of variables in certain types of forest that may affect the distribution, abundance and the nest requirements are important to know to develop a conservation strategy that will allow decision makers to have information that will help in the protection and recovery of the species. This project will be carried out during the breeding season when birds are in the reproductive process and exhibit territorial sedentary behavior and high site fidelity. Sites chosen are areas where the species is known to occur. As a pilot project, this study also documented the nests found within the study sites, almost unknown subject in this species. The information obtained from this information will be used to define study sites for reproductive ecology in consecutive years.