20" x 20" Hidden Zipper in Back Linen with Feather Down Fill and Sunbrella with Faux Down Poly Fill Knife Edge or Corded Finish Hummingbirds are the tiniest birds in the world; a baby is often smaller than a penny. These tiny birds are very smart, though, and can remember every flower they have been to. They can even hear better and see farther than humans. Hummingbirds are able to flash their bright colors and hide them when needed.