Captive breeding of birds can alter the shape of their wings and reduce the chances of survival after release | australian news Liberal-news

Captive breeding can alter the shape of birds’ wings, reducing their chances of surviving migratory flights when released into the wild, new research suggests.

A study of the critically endangered orange-bellied parrot found that in captive-bred birds, those with altered wing shapes had a 2.7-fold lower survival rate than those born with wings close to an ideal “wild-type” wing.

The total population of orange-bellied parrots once dwindled to 17 in the wild, but their numbers have been bolstered in recent years by captive breeding and release efforts in Tasmania and Victoria.

The bird breeds in Tasmania and migrates to the southern coast of mainland Australia for the winter.

Study author Dr Dejan Stojanovic of the Australian National University said there was natural variation in wing feather length in both wild and captive-bred orange-bellied parrots.

“When you look at the length of all the wing feathers, there is a significant difference between the length of the feathers in the captive wings and the wild wings,” he said.

Stojanovic has previously shown that captive-bred orange-bellied parrots tend to have less pointed and shorter wings than their wild counterparts.

“There are variations within captivity of everything from a perfect wild type [wing] to very suboptimal,” he said.

A captive type wing.

In captive-bred birds whose wings most closely resembled ideal wild wings, and which were most likely to survive, a feather known as the distal primary flight feather was longer by only a millimeter.

“Literally the change for orange-bellied parrots is a 1mm difference in the length of a feather. It’s not that easy to detect, but it has this important consequence downstream,” Stojanovic said.

“Few other recovery projects have the scale and resources that orange-bellied parrots have.

“Despite all that care, these changes emerged and also went unnoticed until now. These results also show that these undetected changes were affecting survival, which is a key measure of success to see if we are benefiting the wild population.”

Stojanovic also analyzed the wings of 16 other birds, finding evidence of altered captive wing shapes in four other species: parakeets, turquoise parrots, sunset parrots, and Gouldian finches.

“Clearly, what that shows is that this phenomenon is much more widespread…and it could actually be a [pattern] that had gone unnoticed,” he said. “The next phase is to understand what is really driving these changes.

“Maybe it’s a family trait or an environmental trait… actually, we just don’t know.”

“We need to be better overall at scrutinizing the quality of the animals we’re raising rather than just focusing on their quantity.”

The research was published in the journal EcologyLetters.

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