Bioacoustics reveals the uniqueness of an ex-situ tree hyrax population

Abstract

Tree hyraxes Dendrohyrax spp. are nocturnal, morphologically cryptic and consequently highly understudied mammals. Their taxonomy has always been puzzling, thus their species-level diversity is probably underestimated. Prominent and species-specific songs and loud calls emitted by tree hyraxes are one of the key cues in recognising their diversity. In 2020, a population of tree hyraxes with a specific vocal repertoire not fully matching the vocal repertoire of any known tree hyrax species was discovered in Taita Hills in Kenya. This population might represent a taxon unknown to science. In 2015, calls of a captive group of tree hyraxes that originated from Tanzania and had previously been identified as the southern tree hyrax D. arboreus were recorded in Ostrava Zoo, Czech Republic. Here, calls recorded from this captive group are compared to those previously recorded from other known tree hyrax taxa. The vocal repertoire of this captive population mostly matches the vocal repertoire of the population occurring in Taita Hills. No loud calls nor even the components typically emitted by the southern tree hyrax were recorded from this captive population. Therefore, these captive ambassadors of rarely kept tree hyraxes may have been misidentified as the southern tree hyrax, and may actually be conspecific with the population currently known from Taita Hills in Kenya. Species identification of this tree hyrax population should be a subject of further examination and the captive animals may bring important insights. These findings highlight the importance of mutual cooperation among zoos, academic institutions and museum collections.