Wild Mustang Horses Roaming Free on a Mountainside Aerial Video View taken from a Helicopter Flyby. More than half of all feral Mustangs in North America are found in Nevada (the State Quarter has 3 horses on one side of the coin), with other significant populations in Montana, Wyoming and Oregon. Many animals are kept as pets as opposed to as opposed to livestock, laboratory animals, working animals and sport animals which are kept for economic and business reasons. The most popular worldwide pets are dogs and cats, but there are also rodent pets, such as gerbils, hamsters, chinchillas, fancy rats, and guinea pigs; avian pets, such as canaries, parakeets, and parrots; reptile pets, such as turtles, lizards and snakes; and aquatic pets, such as tropical fish and frogs. Many dog species are kept bred for working purposes such as - livestock herding, game retrieving, detecting narcotics, search and rescue, and racing. Horses are still used on farms worldwide, as pack animals, and for recreation and sporting events. Animals are also widely used in food production including - meat, dairy products, eggs, and fish products. The principal methods of obtaining these products can be grouped under the following categories - Organic farming, Free range farming, Intensive livestock production, Subsistence agriculture, Hunting, and Fishing.