Looks can be deceiving. If you showed me this photo of a Red-winged Blackbird (Agelaius phoeniceus), there’s a good chance I’d say it was a female. For all intensive purposes, it does appear to be of the fairer gender. But there’s a hint that should give the expert pause. The gape, as in the bit of skin at the base of the bill, looks rather prominent, suggesting a young bird. Do you really know that it’s a female if this is a young bird?
This is a little window into how bird banding works. You start with your presumed knowledge and then, if you’re good, try to falsify your hypothesis on species, age, sex, etc. (To be clear, when you catch birds to band, it’s not just to hold a bird and take pictures of them, you are recording data). It’s actually a very fun process.
As it turned out this bird was a young male. A bit of hunting in his coverts and we found the beginnings of his “red-wing” and black feathers were pushing up through his breast plumage. Females are significantly smaller than males also, but without thinking of wing length or weight it’d be easy to make a base assumption and go with it. In the case of a blackbird where size is significant this would be important because a band for a female bird wouldn’t fit properly on a male, it could even be dangerous.
This photo was taken on Shelldon National Wildlife Refuge in Northwestern Nevada at a place called Badger Camp. Although it was late July in Nevada, banding birds here was fantastic, particularly because of the creek that ran right through. Birds came in from all over for water including Western Scrub Jays ( or this blackbird) that you wouldn’t associate with the scrub steppe or grasslands that predominated the landscape.