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
Retort pouch Retort pouch A retort pouch or retortable pouch is a type of food packaging made from a laminate of flexible plastic and metal foils. It allows the sterile packaging of a wide variety of food and drink handled by aseptic processing, and is used as an alternative to traditional industrial canning methods. Packaged foods range from water to fully cooked, thermo-stabilized (heat-treated) high-caloric (1,300 kcal on average) meals such as Meals, Ready-to-Eat (MREs) which can be eaten cold, warmed by submersing in hot water, or through the use of a flameless ration heater, a meal component introduced by the military