Canis lupus
Gray wolves usually live in packs, led by an "alpha pair." The pack includes some of the alpha pair's offspring and may include some unrelated wolves. A pack's territory can be as large as 13,000 square km. Howling probably helps advertise who "owns" a particular piece of territory.
digestive system
Inside the digestive system, the stomach is large and muscular, making it possible to eat large amounts of food in a small time span. The stomach is highly acidic, allowing for ingestion of whole bone pieces that can be broken down into a powder-like substance. This extraordinary acidity also allows a canine to ingest large amounts of harmful bacteria without being affected. This provides dogs with the ability to eat rotting carcasses in times of need, a good survival mechanism. The pancreas of the dog is much smaller than a human's and only contains a fraction of the enzymes that we are able to produce. This means that the food items that a dog eats must come complete with the active enzymes needed to bind with stomach acid and break down food for absorption.