A great tit and blue tit - but what's wrong?

A great tit and blue tit - but what's wrong?

Observation - A great tit and blue tit - but what's wrong?. Description: The blue tit has been around since last year I think (sorry for the poor photo) but the Great Tit is new - what is causing the deformities?

The blue tit has been around since last year I think (sorry for the poor photo) but the Great Tit is new - what is causing the deformities?