Deriving the functional significance of olfaction in a solitary non-territorial herbivore: The bare-nosed wombat Vombatus ursinus

An understanding of mechanisms by which non-territorial solitary mammalian species receive, produce, and respond to communication signals has remained limited, particularly for marsupials. The bare-nosed wombat (Vombatus ursinus) represents a potentially tractable marsupial system to understand communication in a solitary non-territorial herbivorous mammal, particularly as a function of their distinct cube-shaped faeces that facilitate deposition in aggregations. We undertook a multifaceted approach to assess evidence of scat-associated olfactory communication and create a foundation for further research in bare-nosed wombats, linking themes of capacity for signal reception, signal location in the environment and emission and signal response. First, cranial sections identified gross morphological features consistent with a vomeronasal organ, indicative of developed olfactory signal reception. Second, field surveys demonstrated that bare-nosed wombat latrines are associated with features in their landscape (particularly rocks, logs, and burrow entrances), which we hypothesize serve as a visual cue for locations where olfactory communication is concentrated. Third, gas-chromatography/mass-spectrometry on scats showed individually distinctive chemical signatures. Finally, using field experiments, we showed that introducing scats from unfamiliar bare-nosed wombats increased investigatory behaviors at manipulated latrines, and that these effects may depend on local recruitment and latrine density. Collectively, our research provided evidence that olfaction is functionally significant in bare-nosed wombats, provides a foundation from which more detailed investigations can build upon, and suggested this marsupial species is a tractable system for research on communication in a non-territorial solitary mammal.