Ecology of Nesting Laughing Falcons and Bat Falcons in Tikal National Park, Guatemala: Foraging and Niche Breadth
Type of Culminating Activity
Master of Science in Raptor Biology
Three years of breeding season data were collected on the reproductive behavior and food habits of Laughing Falcons, Herpetotheres cachinnans, in northern Guatemala to describe aspects of foraging and nesting ecology of this little-studied species. Twenty-three nesting attempts were observed at thirteen nest sites. Vocalizations, nest sites and associated hymenoptera were described and growth curves developed from measurements of the young. There was an indication that nesting attempts associated with nidicolous ants increased fledging success, possibly by decreasing ectoparasite (likely Philornis sp.) loads. Foraging and habitat information was gathered through telemetry studies and observations of un-telemetered birds. Laughing Falcons foraged in every available habitat, showing a preferrence for intact forest and arboreal snakes. They utilized a range of forest strata, from <2 m to emergent canopy trees. It was found that Laughing Falcons were monophagous, eating only snakes in the primary forest of Parque Nacional Tikal and polyphagous outside the borders, where slash-and-burn agricultural practices have modified the landscape. Herpetofauna comprised the majority of Laughing Falcon diets from an observed total of 767 prey items. In mosaic, altered landscapes, Laughing Falcons foraged for snakes, lizards, some small mammals, birds and fish. These birds illustrate a remarkably clear example of an optimally-foraging species, acting as snake specialists in intact rainforest and generalists in human-altered, mosaic habitats.
Four pairs of Bat Falcons, Falco rufigularis, were observed in the tropical dry rainforests of Tikal National Park in northern Guatemala to describe feeding ecology and behavior of males and females in this highly sexually dimorphic aerial predator. Food deliveries were observed to identify the relative abundance and importance of different prey species in the diet of males and females. Prey items were identified to the species level when possible and prey biomass estimates were made. Prey remains were collected daily from one nest. Over 1,500 observational hours at the four nests identified 197 prey species and very little difference between sexes in prey size or type. Hunting excursions were observed above the canopy at two nests and capture attempts were recorded to reveal no significant differences in success rates between males and females. There were, however, significant differences between nests as to prey types, prey biomass and the female's contribution to prey deliveries. Novel foraging behavior was observed as Bat Falcons gleaned insects from tree leaves.
Parker, Margaret N., "Ecology of Nesting Laughing Falcons and Bat Falcons in Tikal National Park, Guatemala: Foraging and Niche Breadth" (1997). Boise State University Theses and Dissertations. 692.