A crop is a thin-walled expanded portion of the alimentary tract used for the storage of food prior to digestion that is found in many animals, including gastropods, earthworms, leeches, insects, and birds.
Cropping is used by bees to temporarily store nectar of flowers. When bees "suck" nectar, it is stored in their crop.
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.
- Worm World: About Earthworms- http://yucky.discovery.com/flash/worm/pg000102.html
- R. T. Sawyer, Leach Biology and Behaviour, Volume II - http://www.biopharm-leeches.com/pdf/bioandbehav.pdf
- Honeybee Biology - http://koning.ecsu.ctstateu.edu/Plants_Human/bees/bees.html
- The Alimentary Canal in Birds - http://www.earthlife.net/birds/digestion.html