Thursday, 21 August 2014

Seeing red: yet another post on sexing Goldfinches.

I have caught a few more adult Goldfinches in recent weeks and this has allowed me to add to my collection of photographs of known sex birds. I now have a much better understanding of the variation in the plumage features that are normally used to sex Goldfinches. Although the sample size isn't very big, only 14 birds made up of 9 males and 5 females, it should be reasonably representative of the population as a whole. All of these birds had their sex confirmed by the presence of a good incubation patch  for females and the shape/size of the cloaca for males.

These birds clearly show that there is much more overlap in the extent of the red face mask than is usually described in sexing guides and more than I had shown in my previous posts on this subject. The 14 birds caught this summer have taught me more than the 400+ caught during the autumn and first half of last winter. Four of the five females in my sample had red that extended well beyond the eye and equalled or exceeded that of some of the confirmed males. With that in mind lets have a look at some of the most recent photos. What sex do you think these birds are? - the answers are further down this post.

The colour of the mask varies quite a bit from an orange red through red to a rich crimson but both sexes display the same variation in colour so there is no help there. The colour of the nasal hairs can help but some females have dark grey or blackish nasal hairs like males. Just to confuse matters both males and females frequently have a fringe of white feathers or white tipped feathers at the front of the crown and these shouldn't be mistaken for nasal hairs although it is easy to be distracted by them.

Before I tell you the sexes of the birds shown in the pictures above lets have a look at a photo of a female that fits the description in most guides. In my experience females that look like this seem to be the exception rather than the rule.

If all female Goldfinches looked like this sexing them would be fairly straightforward but unfortunately they are not.

1. male
2. male
3. female
4. male
5. male
6. male
7. female
8. female

I hope you find these photos as useful as I have. The stand out birds for me are the female in photo 3 and the males in photos 4 and 5. The photos show that there is more overlap in the extent of the red mask than is often appreciated and described in ageing and sexing guides. In fact there is probably less overlap in the appearance of the lesser coverts compared to all the other features with most females displaying a brown shoulder patch.

Outside the breeding season quite a large proportion of birds will always be difficult to sex with any degree of certainty, even when using every criteria, and I hope my posts and numerous photos have gone some way to show that. Just don't focus on red mask and let that influence you too much as it could just point you in the wrong direction.  And finally the female in photo 3 also had 3 sub-terminal white tail spots dispelling the myth that only males have 3.

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