Western Scrub Jay in Santa Fe, NM.
© Peter Wallack
Most people, even most kids, know that birds have no teeth.
Likewise, it’s common knowledge that quite a few birds consume almost exclusively hard foods such as grains and seeds.
So so how do birds digest these tough morsels if they can’t chew them into more edible pieces?
The answer lies in a bird’s stomach—in the lower part of its stomach, to be specific, the area called the gizzard. It’s here that the powerful mixing and gnashing of food that occurs in human mouths takes place in birds.
But rather than bicuspids, molars, and the like, the gizzard uses small rocks, shells, and sand to break apart hard foods. The bird swallows these rocks and whatnot specifically to help with digestion. And when they wear down, as inevitably happens, the bird simply passes them on as waste and consumes a fresh supply.
Almost every species of bird has a gizzard,as do some species of reptiles, earthworms and fish. A bird’s gizzard has thick, muscular walls and is lined with a protective substance known as koiln.
So having a gizzard is a bit like having a drawer filled with spare teeth—only without the dentist’s bills!