crop
A pouched enlargement of the gullet of many birds that serves as a receptacle for food and for its preliminary maceration. [ http://purl.obolibrary.org/obo/BTO_0000301 http://en.wikipedia.org/wiki/Crop_(anatomy)#Birds ]
Term info
crop
we follow WP and place as part of the esophagus
esophageal diverticulum
uberon
esophageal pouch
UBERON:0007356
Aves specific structure - consider adding functional grouping class. Kardong: some cetaceans have a crop-like structure