Rock Cavy (Kerodon rupestris) lives in rocky grasslands across Eastern South America. It feeds on grass and leaves. Its conservation status is Least Concern.
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A real field recording of the Rock Cavy, made in the wild.
Its body and habits look almost identical to the unrelated African rock hyrax, a classic case of convergent evolution. The rock cavy is a fairly large rodent that can weigh up to 1 kg and has a vestigial or absent tail, with a grey-brown back and lighter belly. It inhabits dry, rocky terrain with low scrubby vegetation, staying close to stony mountainsides and hills.
Rock cavies have a direct link between their retina and the mediodorsal nucleus in the thalamus. This neural connection is thought to give them strong visual recognition and may enhance emotional learning or object-reward associative memory. Such heightened perception likely supports their social structure, as they are frequently observed living in large groups. The visual system therefore underpins both individual cognition and group cohesion.
Male rock cavies sometimes court other males, displaying homosexual behaviour. This behaviour has been observed in their social interactions.
Adult male rock cavies sometimes direct courtship toward younger males, a behaviour described as paedophilic. This occurs in a species where males are highly territorial, constantly defending rock-pile shelters against rival adults. The same males also display homosexual interactions, courting other adult males. Such social complexity is linked to their group-living habit centred on rock-sheltered dens.
Female rock cavies select mates based on the quality of the rock pile a male defends, so when a female settles on a pile she also chooses the defending male as her mate. Groups are organised around these rock-sheltered dens, each led by an alpha male and attended by several females.
Sources
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In the sun-baked hills of Brazil, the rock cavy navigates its arid kingdom with an air of quiet confidence, its sturdy legs and sharp claws allowing it to scale rocky outcrops with ease. As it moves through the scrubby landscape, its large, dark eyes seem to drink in every detail, ever vigilant for the predators that lurk in the shadows. With its distinctive black and brown coat glistening in the bright light, this remarkable creature embodies the very essence of resilience, thriving in a world of rugged beauty and unforgiving extremes.
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