Australian Painted-snipe gender [SEC=UNOFFICIAL]

["Perkins, Harvey" <>]

Hi all,

 

It's great to hear that so many people are seeing the two Australian Painted-snipe out at Kellys Swamp over the past four days.

 

When first found, I think there was a general assumption that the two birds represented a female/male pair, supported by the fact that one of the birds was smaller and duller and assumed to be a male. Early on I threw out the suggestion that they might in fact be two females but there has been little input on this from subscribers.

 

Having now looked at a wide range of references and familiarised myself with what painted-snipe look like (it is after all the first time I've ever seen one), there is no doubt in my mind that the two birds are both females.

 

There never was any doubt about the larger brighter bird being a female. But the colour and patterning of the wing coverts (visible as the closed wing) are the same in both birds and are diagnostically female (greenish with fine black wavy barring or "vermiculations"). A male bird would have lots of obvious creamy-buff spots. The rufous patch on the back of the neck, which the smaller bird has, is also diagnostically female.

 

The wing pattern also rules out the smaller bird being a juvenile, of either gender, as juveniles also have spotted wings.

 

The fact that the smaller bird lacks the bright (white) eye mark and is generally duller around the head and breast, presumably then indicates that it is an immature bird which is in the later stages of attaining full adult female plumage.

 

The size difference appears to be what would be expected between a female and male (a range of linear dimensions from HANZAB suggest that females are on average 6% bigger than males), but there is also overlap in size between larger males and smaller females. So this probably just happens to be a smaller female bird.

 

Finally, a couple of indirect references in HANZAB suggest that two females occurring together might not be particularly unusual.

 

Thems my thoughts, anyway.

 

Harvey

 

 

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