A bird builds a compost-powered nursery and checks its temperature with its own beak

The malleefowl of Australia builds a mound of leaf litter and sand up to a metre high and several metres wide, where decomposing plant matter generates steady heat to incubate its eggs. The male spends nearly all year tending it, repeatedly digging into the mound and apparently using sensors in his beak or tongue to gauge the temperature, adding or removing material to hold it near 33°C.

— H.J. Frith, Malleefowl — CSIRO behavioural field studies, 1950s-60s