In captive-bred birds whose wings most closely resembled the ideal wild wings – and which were more likely to survive – a feather known as the distal primary flight feather was longer by a single millimetre. “There’s variation within captivity from everything from a perfect wild type to very suboptimal,” he said. Stojanovic has previously shown that captive-bred orange-bellied parrots tend to have less pointed and shorter wings than their wild counterparts.

“When you look across the lengths of all the feathers on the wings, there’s a significant difference between the lengths of feathers in captive wings versus wild wings,” he said. Sign up for Guardian Australia’s free morning and afternoon email newsletters for your daily news roundup The study’s author, Dr Dejan Stojanovic, of the Australian National University, said there was natural variation in wing feather lengths in both wild and captive-bred orange-bellied parrots. The bird breeds in Tasmania and migrates to mainland Australia’s southern coast for the winter. The total population of orange-bellied parrots once dropped as low as 17 in the wild, but their numbers have been bolstered by captive breeding and release efforts in Tasmania and Victoria.

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