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
Birds of the West Indies figure — an anonymous, blunt instrument wielded by a government department." The book has since become a collector's item amongst Bond fans and was featured as an homage in the twentieth James Bond film, "Die Another Day", when Bond poses as an ornithologist while in Cuba. The final shot of the miniseries "" is of a copy of "Birds of the West Indies" next to Ian Fleming's typewriter. Birds of the West Indies Birds of the West Indies () is a book containing exhaustive coverage of the 400+ species of birds found in the Caribbean Sea, excluding the ABC islands,