This bird should be moulting around about now. How does it look?
I doubt it's melanism, as that's related to a severe lack of natural light (yes?) so the other birds would also be affected...unless this one has a genetic defect in that system. None of the potential crosses seem like they could produce this colouring. I'm very curious to see how it turns out after its first moult.
Hi Arthur,
I think what Finchy means is that many melanistic finches are the result of acquired melanism due to lack of sunlight rather than the genetic melanism that you speak of. I've seen it in strawberries, orange-breasts, cubans & these have moulted out once fed a varied diet & given access to direct sunlight.
Having said that, given that this is a fledgling and also looking at the colour distribution pattern I agree that this is more likely to be genetic than acquired or as others have suggested possibly even a hybrid. It will certainly be interesting to see how it moults out.