Pygmy marmosets are the world's smallest monkeys, with highly specialised social structures and dietary needs that present unique welfare challenges in zoo settings despite their small physical size.
Pygmy marmoset welfare challenges arise from the mismatch between their tiny physical size — which might suggest minimal space requirements — and their complex social, dietary, and behavioural needs that are substantial for their body mass. Family group social housing is essential: isolated individuals show severe stress responses and fail to reproduce. The gum-gouging feeding behaviour is strongly motivated and must be facilitated through exhibit features that allow gnawing and access to gum or suitable substitute materials. Temperature stability is critical for animals with a high surface area to volume ratio that makes them vulnerable to thermal stress. The ultrasonic communication dimension of pygmy marmoset welfare is poorly understood but relevant: acoustic environments that interfere with communication frequencies may impair social coordination. Their small size also means that predator vigilance is high — secure exhibit design without threatening stimuli from nearby carnivore exhibits reduces chronic fear stress.