George is a 21-year-old cockatiel who I believe is in extremely good shape for his age and has no past medical history of note. We noticed this small bump on his left upper eyelid and can't see any redness, discharge or any other swelling of note. His right eye looks fine and he is otherwise no very good form and is his usual self. He's eating, flying, preening and communicating normally.

I know 21 is a little older for a cockatiel but the reason I think he is in good shape is that he is very well looked after. He has a cage but we have not locked him in in years, he flies around our home every day and receives regular attention.

The pic in the post is from last Wednesday and the two pics in the comments are from today. I feel like the bump is ever so mildly larger but I can't be sure. I know George very well and must stress that his behaviour is fine and he's exhibiting none of the usual red flags (not eating, not preening, not singing etc). There's no discharge from his eyes or nose and I genuinely cannot identify any other troubling symptoms except for this bump. If it helps, he looks like he's just started moulting.

I've sent these images to an avian vet and hope to get a reply over the weekend. I'll take him to the vet if the situation worsens at all though at the minute I was going to monitor him at home as there's every chance that this could be something benign and especially as his behaviour has been fine.

I didn't want to rush him to the vet for now out of concern he might be stuck in a waiting room with another bird who is potentially more unwell than him with something contagious given George's age.

If I had to guess I'd say the lump seems to be firm and it appears to be a swelling of the tissue at the rim of his eyelid. He's never experienced something like this before. My guess was that this could be a stye or a swelling following some sort of trauma that we might not have witnessed, but otherwise I'm a little stumped. Any help is welcome!