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
Endangered Species Act of 1969 passed prior to the 1969 act, and set up a list of species native to the United States that qualified as endangered. The animals on this list were then afforded certain protections from the National Wildlife Refuge System. For example, the Endangered Species Preservation Act was in part dedicated to raising awareness of endangered species of birds like the peregrine falcon, and to "conserve, protect, restore, and propagate certain species of native fish and wildlife". Despite these protections, however, researchers found that the act was insufficient. This led to the passage of the Endangered Species Conservation Act of 1969. The