Range sizes and habitat use of non-breeding Crested Caracaras in Florida

Abstract

In Florida, habitats that include the breeding territories of Crested Caracaras (Caracara cheriway) are protected, but non-breeding individuals may be vulnerable because they may occupy different areas and habitats. We captured and radio-tagged 58 non-breeding caracaras in Florida from July 2006–March 2009, determined their locations during weekly flights, and used GIS and compositional analysis to evaluate range sizes and habitat use. Non-breeding caracaras (N = 58) ranged five times more widely during breeding seasons (N = 573 locations) than during non-breeding seasons (N = 592 locations), and ranged >250 times more widely than breeding caracaras that defend territories year-round. The large ranges of non-breeders suggest they may be searching for and evaluating prospective territories or breeding opportunities (territory prospecting). Pasture occupied by cattle was the most used habitat relative to availability and was used more than pasture without cattle, likely because insects associated with cattle are an important food source for caracaras. Cattle numbers in Florida are declining and, because both breeding and non-breeding caracaras primarily occupy pasture, this may present difficulties for long-term management. Citrus groves were also used more than expected given availability by non-breeding caracaras, but are rarely included in nesting territories. Because pasture and citrus were often adjacent, we suggest that citrus groves may function as refugia from socially dominant breeding caracaras. Conservation and recovery efforts for Florida's caracara population are needed throughout the range of non-breeders, and should include management that ensures availability of habitat matrices of cattle pasture and citrus groves.