in assigned positions and assistants to help load shotguns. When in position, "beaters" move through the areas of cover, swinging sticks or flags to drive the game out. Such events are often called "drives". The open season for grouse in the UK begins on 12 August, the so-called Glorious Twelfth. The definition of game in the United Kingdom is governed by the Game Act 1831. A similar tradition, , exists in Spain. United States North American hunting pre-dates the United States by thousands of years and was an important part of many pre-Columbian Native American cultures. Native Americans retain some hunting rights and are exempt from some laws as part of Indian treaties and otherwise under federal law—examples include eagle feather laws and exemptions in the Marine Mammal Protection Act. This is considered particularly important in Alaskan native communities. Hunting is primarily regulated by state law; additional regulations are imposed through United States environmental law in the case of migratory birds and endangered species. Regulations vary widely from state to state and govern the areas, time periods, techniques and methods by which specific game animals may be hunted. Some states make a distinction between protected species and unprotected species (often vermin or varmints for which there are no hunting regulations). Hunters of protected species require a hunting license in all states, for which completion of a hunting safety course is sometimes a prerequisite. Typically, game animals are divided into several categories for regulatory purposes. Typical categories, along with example species, are as follows: Big game: white-tailed deer, mule deer, moose, elk, caribou, bear, bighorn sheep, mountain goat, pronghorn, pigs (both wild and feral), javelina, bison Small game: rabbit, hare, squirrel, opossum, raccoon, porcupine, skunk, ring-tailed cat, armadillo, ruffed grouse Furbearers: beaver, red fox, mink, pine marten, musk rat, otter, bobcat, coyote Predators: cougar, wolf, coyote Upland game bird: grouse, woodcock, chukar, pheasant, quail, dove Waterfowl: duck, teal, merganser, geese, swan Hunting big game typically requires a "tag" for each animal harvested. Tags must be purchased in addition to the hunting license, and the number of tags issued to an individual is typically limited. In cases where there are more prospective hunters than the quota for that species, tags are usually assigned by lottery. Tags may be further restricted to a specific area, or wildlife management unit. Hunting migratory waterfowl requires a duck stamp from the Fish and Wildlife Service in