Does a gape flange always indicate a bird is juvenile? (1 Viewer)

I was ringing some Northern Masked Weavers today and I had my first opportunity to handle some juveniles. I have not worked with juvenile passerines for many years, but I assumed the ID of juveniles would be easy. However, I found myself a bit confused, especially with birds that were moulting flight feathers and had pale eyes (as I had, perhaps foolishly, assumed the lighter coloured eyes would the older birds). Many of the birds had a distinct gape flange, which I remember from many years ago being a good indicator of a juvenile, but I am wondering how certain it is.
There is little information on weaver moult, but it seems that many have a complete post-juvenile moult, so it may be that my confusing birds were early fledgelings that have already developed a pale eye and are moulting, yet still have the gape flange.
The first two photos show the head and wing of one of these confusing birds. The moulting remiges show a distinct difference between the older pale brown feathers and the newer ones, which made me first think it was an older bird. However the head shot seems to show a distinct gape flange. Also, the older unmoulted feathers show little wear, which would indicate that it might be a juvenile. Many of the adults caught today had very abraded tips to their primaries. I have also attached a photo of a known adult for comparison, which was trapped near the start of the breeding season in May when there would be no juveniles around.
I would appreciate your comments on my identification of the first bird as a juvenile based on the gape flange. I did not record skull ossification.
Thanks

Tom

I've sometimes wondered about this myself. I'll be very interested to hear what the experts have to say.

I´m by no means an expert but I´ll not hesitate to post my belief.

IMO the birds with the bright gape flangs are juveniles. I´ve breed a lot of estrildae finches: Cordon bleu´s, Gouldian Finches, parrotfinches, gras finches, etc.
I very well know that weavers aren´t Estrildidae but all juv. of them has bright gape flanges, often "supported" with differend bright colors.
Eg.: Gouldian Finch:
http://static.panoramio.com/photos/original/29613807.jpg
By all my birds the flange gape went away during post- juvenil moult. Approximately ~6 month, depending on the species.
In your case it doesn´t go away just darken, both flange color and eye color.
Maybe I was of some help.

Thanks for the comments so far. I would still welcome further confirmation.
Thanks

Tom

Something I've observed in juveniles of House and Spanish Sparrows is the apparent retention of some minute feathers on the lores following an otherwise complete PJ moult. Your adult bird seems to have bare lores, while the supposed juvenile has some feathering. Maybe worth keeping an eye on this?

Many years ago a very experienced ringer suggested to me that the soles of the feet might be used to gauge the age. This was before the arrival of the modern technique of looking for a moult limit in presumed young birds that have undergone partial moult. Unluckily, you are dealing with a group of finches that have complete PJm.

As you are in a warm country, I'd see nothing wrong in wetting the crown to aid 'skulling'. A jeweller's eyeglass or similar aid is also invaluable in doing this.

Thanks for the advice John. I take lots of photos of every bird, so I will go back and look at the lores, and maybe even the soles of the feet! I think I will have to start looking at the skull ossification when I next catch some weavers, especially any that are ambiguous.

Tom

Have a look at the ringing guide on the A.P. Leventis Ornithological Research Institute:

http://www.aplori.org/database/default.aspx

I suspect eye and bill colour is going to be your best bet.

Ross

A very useful website for me Ross. Thanks you.

Tom

If I remember correctly, the adult Bananaquit (yes, very different family compared with your weavers) have swollen gape flange (red) in adult male, so different passerines do different things

Niels