The weeping vocalization of the screaming hairy armadillo (Chaetophractus vellerosus), a distress call

Abstract

Distress calls are signals given by individuals experiencing physical stress such as handling by a predator. These calls have been recorded in numerous phylogenetically distant vertebrate species, and share certain acoustic features, such as high amplitude, broadband, and rich harmonic structure. Screaming hairy armadillos (Chaetophractus vellerosus) sometimes give a high-amplitude weeping call when captured by predators or disturbed by humans. We provide an acoustic characterization of this call using recordings of hand-held wild individuals, and test whether it constitutes a distress signal. The weeping call was a harsh, loud, broadband, long sound, composed of five note types: crying, inhaled, inhaled sobbing, exhaled sobbing, and grunt notes. Crying notes were the most common, distinctive, and loudest sounds. The proportion of armadillos that called when disturbed was between nearly five to seven times higher than when treated with care. Likewise, 223 hunters reported armadillos consistently weeping when trapped by dogs, and no weeping was heard in natural undisturbed conditions. Our data support a distress signal role for the weeping call.