ABSTRACT

Patterns of animal space use may vary according to species identity, presence of conspecifics, presence of heterospecifics, and resource availability. We evaluated joint space use by Canyon Wrens (Catherpes mexicanus) and Rock Wrens (Salpinctes obsoletus) by comparing home range sizes, home range overlap, and foraging behavior. Canyon and Rock wrens are ecologically similar species which frequently co-occur along rocky cliffs where members of both species feed on terrestrial invertebrates. Interactions between Canyon and Rock wrens provide information about avian space use and foraging strategies in understudied cliff habitats. We estimated home range for each species using ArcGIS, and quantified foraging microhabitat use. Canyon Wren home ranges were widely spaced, did not overlap conspecifics, and were significantly larger than those of Rock Wrens. Rock Wrens occurred at higher densities and home ranges overlapped conspecifics in 33% of cases by an average of 19%. Canyon and Rock wren home ranges overlapped in 68% of cases by an average of 28%, but overlapping pairs rarely shared core use areas. The two species differed significantly in foraging microhabitat use. Results suggest that heterospecific territory defense between Canyon and Rock wrens is low, and that these species have adopted different methods for using shared resources in escarpment and cliff habitats.

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