Intra- and inter-specific territorial response of diurnal raptors in the tropical dry forest of western Mexico

Abstract

Little is known of intra- and inter-specific territoriality in Neotropical raptors that may defend territories throughout the year, and face greater inter-specific competition for resources. We evaluated intra- and inter-specific territorial responses of four species of Neotropical raptors in the tropical dry forest of the Chamela-Cuixmala Biosphere Reserve, Mexico. We conducted broadcast calls in territories of the Collared Forest-Falcon (Micrastur semitorquatus), Crane Hawk (Geranospiza caerulescens), Gray Hawk (Buteo plagiatus), and Roadside Hawk (Rupornis magnirostris), and measured the latency, duration, and type of territorial response to broadcast calls of conspecifics and sympatric raptor species. We applied repeated measures analysis to determine differences in intra- and inter-specific territorial responses of raptors, and GLMMs to evaluate whether traits of body size, nest type, and hunting technique were associated with territorial response by focal raptors. Large-bodied focal raptor species showed high intra-specific territoriality, giving faster, prolonged responses of various types, including duets and combined responses, to broadcast calls of conspecifics compared to sympatric species. All focal raptors showed some inter-specific territorial response, but this was mainly as vocalizations or displacements towards sympatric species broadcast calls. Species traits of body size, nest type, and hunting technique were associated with latency and duration of territorial response by the larger raptor species that nest in the forest canopy. These traits may be more strongly associated with territorial response of forest raptors that defend limited resources in a structurally complex environment.