Bird anatomy Birds have a four-chambered heart, in common with mammals, and some reptiles (mainly the crocodilia). This adaptation allows for an efficient nutrient and oxygen transport throughout the body, providing birds with energy to fly and maintain high levels of activity. A ruby-throated hummingbird's heart beats up to 1200 times per minute (about 20 beats per second). Many birds possess a muscular pouch along the esophagus called a crop. The crop functions to both soften food and regulate its flow through the system by storing it temporarily. The size and shape of the crop is quite variable among the birds. Members
An Annotated Checklist of the Birds of the Oriental Region An Annotated Checklist of the Birds of the Oriental Region An Annotated Checklist of the Birds of the Oriental Region is a 1996 softback book published by the Oriental Bird Club, and authored by Tim Inskipp, Nigel Lindsey and Will Duckworth. It contains a list of all 2,586 species recorded in the Oriental Bird Club's areas of operation up to the date of publication. This area approximates to that covered by the Oriental zoogeographical region, with the exception that for countries such as China and Pakistan which straddle the Oriental / Palaearctic boundary, the whole country is included; those species