A Blue Tit with a deformed beak has been visiting the garden for the past couple of months. Its very overgrown mandibles clearly cause it problems when feeding but it has adapted by tilting its head to one side and searching through suet pellets on the bird table to try and find smaller pieces and crumbs it can pick up and eat. It frequently feeds on the ground below a fat ball feeder where it can also find small pieces and crumbs that other birds drop or dislodge when feeding on the fat balls.
More recently it has taken to using a window feeder that allows it to pick through sunflower hearts, suet pellets and partially crushed dried mealworms. I wouldn't normally use a window feeder but it was bought for me as a Christmas present so I decided to give it a go and I am really glad that I did. Birds didn't go near this feeder for ages but this Blue Tit eventually started to take advantage of it and brought it close enough for me to photograph it.
This isn't the first Blue Tit with an overgrown beak I have recorded in the garden and I did a blog post about one I caught in the garden nearly 10 years ago (blog post link here). That bird was more extreme case and had an even longer lower mandible. One thing I have noticed with the current bird is that its bill still appears to be growing, especially the lower mandible. When I first saw it in the garden the lower mandible barely seemed to extend much beyond the upper mandible where they cross but now it clearly extends past the upper by a few millimetres. I suspect both mandibles are still growing but it is just easier to see the change in the lower mandible. If it hangs around long enough I may be able to take more photographs to show that its bill is still growing in the absence of normal wear from pecking, feeding and bill wiping.