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
Catcher pouch train's catcher arm, he might miss the catcher pouch altogether. In the United Kingdom as early as 1855 an apparatus for snatching mailbags on-the-fly and delivering mail without stopping a train was in use at Slough, England. It continued in service until 1939. Catcher pouches could not be used for any other purpose. The catcher pouch was to be used only for letters (sometimes newspapers were an exception). The maximum weight of a filled catcher pouch was to be 50 pounds. The catcher pouch was to be locked and placed upside down on the mail crane no sooner than 10