Growth and development of Buff-banded Rail chicks

Abstract

The Buff-banded Rail Gallirallus philippensis is not uncommon in favourable parts of its range but its elusive nature makes it difficult to study and, in particular, development of chicks to attainment of juvenile plumage and adult size is incompletely reported. In the northern suburbs of Canberra, Australian Capital Territory, planned storm-water management has resulted in the formation of wetlands, watercourses and pools, an ideal environment for rails and crakes. Physical and behavioural development could therefore be followed from opportunistic observations and photography of three broods of chicks, from black downy hatchlings to fully fledged juveniles, at Forde Creek in 2014–2015. The first feathers were visible on the fourth day. All the down had been replaced with feathers by around the third week, by which time the juveniles were about half the size of the adults. The juvenile Rails took another 3 weeks to fully develop the distinctive juvenile plumage patterning, similar to but duller than in adults, and by this time they were the same size as the adults. Although the rate of plumage development is broadly consistent with the literature, the growth rate was slower than the widely quoted figure of adult size being reached in 3 weeks. Observations over 107 days in summer 2014–autumn 2015 provided an opportunity to observe the behaviour of dependent chicks and adults as the chicks developed into juveniles and gained independence.