Since ostriches don't have teeth, they swallows small stones and pebbles which help to grind their food when it reaches the gizzard (second stomach). The gizzard contracts and grinds the stones against each other and against the food that the bird has swallowed.

A hummingbird's brain makes up a whopping 4.2 percent of its weight; proportionally, that's the largest of any bird's. Studies have shown that they can remember every flower they've ever visited, migration routes, and even recognize the humans that fill their feeders.

As their name suggests, acorn woodpeckers drill holes in which they stash acorns. A typical "granary tree" contains hundreds or even thousands of acorns--the largest on record contained around 50,000.

Almost 50% of all parrot species are endangered and almost 25% of the species are critically endangered. The main reasons for this are persistent habitat destruction, such as land clearance with fire or settlement, and the continuing trade in birds, which still offers wild-caught stock.