'Bumbarrel' is an old name for the Long-tailed Tit, everyone's favourite garden bird. And the reason they're called that is for the shape of their nest. It's almost spherical, with a little hole at the front, and made from a special weave of moss, lichen, spiders' webs and feathers.
Spent a few hours at Rainham Marshes today, bitterly cold northerly wind but I did manage 52 species. Highlights included a pair of Bullfinches and the ice had pushed a few Wigeon and Pintail close to the hide.