This is Bird Note. White-breasted nut hatches aren't the toughest birds on the block.

They're petite songbirds that walk upside down on tree trunks looking for food, and their song sounds a bit like laughter.

But when it comes to their nests, nut hatches know how to put up defenses.

Squirrels could easily duck inside a nest cavity and gobble up the eggs.

That's why you might see nut hatches sweeping around their nest hole with a beetle or other insect.

It's thought that chemical compounds from the insect smell bad to squirrels, driving them away.

Nut hatches also might tuck other odorous items in their nest, like a cigarette filter, that smell unappetizing to would-be predators.

But if a squirrel ignores the stink and approaches anyway, white-breasted nut hatches have one more card to play.

They'll stretch out their wings to look as big as possible and sway back and forth threateningly.

They might be small, but nut hatches have the wits and the courage to stop squirrels in their tracks.

For Bird Note, I'm Ariana Rimmel.

Support for Bird Note is provided by Jim and beer-to-fulkner and generous listeners around the world.