Variation in responses to conspecific and heterospecific advertisement vocalizations in sympatric grasshopper mice (Onychomys).

This article investigates the function of long-distance vocalizations in three sympatric species of grasshopper mice (Onychomys arenicola, O. leucogaster, and O. torridus) through laboratory playback experiments. The study found considerable individual and species variation in vocal responses, with the largest species, O. leucogaster, showing greater responsiveness to conspecific calls, while the smaller species responded less specifically and sometimes to control white noise. Results suggest that these vocalizations primarily facilitate localization for subsequent close-range social assessment rather than serving strictly for mate acquisition or interspecific territoriality. The authors note that laboratory conditions and individual variation, including reproductive status and acclimation to captivity, may influence vocal behavior, and they recommend field studies to validate ecological relevance.