The Orange-breasted Falcon Falco deiroleucus in Mesoamerica: a vulnerable, disjunct population?

Abstract

The Orange-breasted Falcon Falco deiroleucus, among the world's most poorly known falcons, is sparsely distributed in Neotropical forests from south-east Mexico or Guatemala to Paraguay and northern Argentina. Details of distribution and population size are poorly known throughout the species's range. From 1992 to 1997 we studied this species at 19 nest sites in Guatemala and Belize. Occupancy and productivity rates remained stable for this northernmost population over this six-year period. Sparse data on historical distribution preclude a full assessment of possible changes in population status in the Mesoamerican portion of the species's range. Today the species appears restricted to forested areas in conjunction with large nesting cliffs. No breeding record is known for any Mesoamerican nation except Belize and Guatemala. Mean number of fledglings per successful nesting was significantly higher in areas of predominantly forested mosaic habitat (2.11, n = 18) than at sites with uninterrupted mature forest (1.36, n = 11); proportion of sites occupied and of pairs fledging young did not differ between these two habitats. Based on historical and current distribution records and distribution of potential nesting habitat, we conclude that the Guatemala/Belize opulation of Orange-breasted Falcons is disjunct from the species's main range in South America, is perhaps the only local population (at best one of a small number) in Mesoamerica, and is tightly linked to the existence of suitable nesting cliffs combined with large forested areas.