Prothonotary Warblers (Protonotaria citrea) Break Their Beaks During Attacks on Wooden Conspecific Decoys

Abstract

ABSTRACT Researchers often use wooden conspecific decoys paired with playback of audio recordings to capture individuals of territorial avian species. Agonistic responses elicited by these decoys can be violent at times; however to our knowledge, there have been no previously recorded instances of physical attacks on a decoy causing injury. In April 2014, we witnessed two cases of male Prothonotary Warblers (Protonotaria citrea) breaking their beaks while attacking a conspecific wooden decoy used during target-netting. Upon recapture 6–8 weeks after initial breakage, beak damage had healed and both males’ mass was virtually unchanged (<1% change from their mass at initial capture). We also observed no detrimental effects of the broken beaks on within-season survival, mate attraction, or territory maintenance. Despite the lack of effect of the breakage on the birds, we suggest the use of softer materials in decoys. In addition to the development of safer practices when target-netting, our observations draw...