Un-bill-ievable Blue Tit

It was a beautiful day today and far too sunny to put a net up in the garden until the sun moved round behind the house and put the front garden net site and feeders in shade. I put a net up at around 2:15 with the intention of catching a few more Goldfinches and the first birds were caught within a few minutes. These were a Starling, a Goldfinch and a Blue Tit with an incredibly deformed bill.



Un-bill-ievable Blue Tit

I have caught birds with deformed bills before but nothing like on this scale. Both the upper and lower mandibles were hugely overgrown. How it feeds is any ones guess but it clearly does well enough as it was a healthy adult. That makes it in the region of 18 months old at the very least but it could be much older.

The uniform blue colour of all the coverts and blue primary coverts
in particular show that this bird is an adult.

I have not seen this bird in the garden before and it wasn't a bird I had ringed previously so I don't know any of its history. It will be interesting to see if it turns up in the garden again as I would like to see how it feeds. It is always tempting to interfere and trim the bill in a case like this but I didn't and wouldn't. It is a natural deformity and ringing is all about studying birds without any undue interference.

Whichever way you look at this bird it sure looks odd.

BTO garden bird surveys have revealed Blue Tits to be the most frequently recorded species with beak deformities and you can read more by clicking here. Coincidentally a post about a Blue Tit with a deformed bill has been published recently on the BTO 'Demog Blog' and can be seen by clicking here.

Here are some of the measurements.

Ringing totals for 30/11/13 with retraps in brackets.
Goldfinch 5 (1)
Starling 1
Blue Tit 1
Robin 1
Long-tailed Tit (1)
Total 8 (2)