According to wikipedia: "In a bird's digestive system, the crop is an expanded, muscular pouch near the gullet or throat. It is a part of the digestive tract, essentially an enlarged part of the esophagus. As with most other organisms that have a crop, the crop is used to temporarily store food. Not all birds have a crop. In adult doves and pigeons, the crop can produce crop milk to feed newly hatched birds. Scavenging birds, such as vultures, will gorge themselves when prey is abundant, causing their crop to bulge. They subsequently sit, sleepy or half torpid, to digest their food." Source: http://en.wikipedia.org/wiki/Crop_(anatomy)

Do most birds fly back to a safe location, regurgitate it out, and then snack at their leisure? If it's part of the digestive system, wouldn't the digestive enzymes start breaking the food down, and make it unsuitable for longterm storage? Why do some have them and some not? I would think it would be so handy that all birds would have them. Do crops run a danger of being lacerated by sharp seeds or is the esophageal tissue there much sturdier than our own?

I observed a Steller's Jay filling his crop to the max with corn kernels from a squirrel feeder today. In this picture, you can see the redness of a featherless area as the crop has expanded:
http://i33.tinypic.com/5vmzr6.jpg

Marian Murdoch
Belfair, WA
http://wildmaven.org
marianmurdoch at yahoo.com