Most birds are generally pretty secretive when building their nests (except for when they're big, like herons' nests, or just plain obvious, like house martins').
This weekend, be a bit of a bird detective and see if you can see a bumbarrel.
Yes, you read correctly.
'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.
Long-tailed tits can be quite tame and not too scared of humans. I bet that if you see a pair of long-tailed tits this weekend and watch them carefully, you'll almost certainly spot where they're building their nest. It can be quite high up in a tree, or low down in a bramble bush. Just watch for them carrying their construction materials.
It's important that you don't get too close or you could disturb the birds, so it's best to stand back a distance and watch through binoculars.
Have fun and let us know what you see!