Slow continuous wing-moult of Zebra Finches Poephila guttata from southeast Australia

Moult of the remiges was studied over eight years in a population of Zebra Finches from southeast Australia. In first-year birds the first primary was lost at mean age of 80 days in both sexes; moult took 204 days to complete in males and 223 in females. Birds hatched in autumn postponed the start of their primary moult until spring. Primaries were replaced slowly in a rigid, non-overlapping, ascending order from #1 to #9 but the secondaries did not display a rigid sequence.
Adult Zebra Finches moulted remiges throughout the year. Primary moult was initiated in any month. Primary moult had a mean duration of 229 days for males and 240 days for females. Primaries moulted in continuous waves: the interval between successive moults in males was –16 days and +6 days in females. Limited food, low temperatures and breeding slowed, but did not stop, wing-moult. Birds caring for eggs and young actively replaced remiges.
The pattern of wing-moult displayed here by Zebra Finches is exceptional for passerines and may be related to the opportunistic breeding strategy necessary in an arid, unpredictable environment. Its presence in the Victorian birds may be non-adaptive.