Use of Anthropogenic Nest Substrates by Crested Caracaras

Abstract

Caracara cheriway (Crested Caracara) typically nest in Sabal palmetto (Cabbage Palms) in Florida and isolated thorny shrubs (e.g., Celtis pallida [Granjeno]) in Texas. The species has not previously been reported to use anthropogenic nest substrates. We found Crested Caracara nests in an electrical substation, on a radio tower, and on a billboard near Clewiston, FL, and in an electrical substation and on a lattice electrical-transmission tower near Houston, TX. Our observations of nesting on anthropogenic substrates may support 3 distinctly different inferences. First, the behavior could be ongoing but not previously reported. Second, because individual Crested Caracaras in breeding plumage persist for years as floaters, novel use of anthropogenic nest substrates may indicate adult Caracaras seeking any possible nesting opportunity, even if nest success is low. Third, Crested Caracaras may be modifying their breeding behavior to capitalize on high-quality resources in areas that lack traditional nest substrates. Comparison of productivity between nests on anthropogenic and natural substrates would resolve the latter 2 competing hypotheses. Because management focuses primarily on nest sites, novel nesting-behavior could have important management implications. Future research should quantify productivity on anthropogenic substrates and document whether individuals produced at these sites tend to return to anthropogenic substrates to breed.