CONCORD, N.H. (AP) — New Hampshire wildlife officials are asking the public to report sightings of free-ranging feral swine—known more commonly as wild pigs, wild boar or feral hogs.

The animals are not native to North America and have expanded their range from 17 to 39 states in the last 30 years. They currently are found in many northeastern states including New Hampshire, Maine and Vermont.

Officials say the animals' expanded range is a concern to farmers, homeowners, animal health officials and others. The animals annually are estimated to cause $1.5 billion in damage. They use their snouts to uproot vegetation and earth in search of food—damaging lawns, backyard gardens, parks and golf courses. They also trample crops and create mud bath wallows in pastures.

Officials say the animals also devastate native habitat by thwarting forest regeneration and contaminating water supplies.

Feral swine have no legal game status in New Hampshire, but are considered escaped private property and may only be hunted with permission of a property owner.

Feral swine come in many colors, shapes and sizes, but are most commonly black or brown. An average adult weighs between 100 and 200 pounds. Most of their activity is at night, but they leave behind signs to indicate their presence such as a rooting, wallow and tree rubs. Tracks are similar to deer, though swine hoofs are rounder and tend to be more splayed and blunt at the tips.

Officials are seeking the public's help mapping distinct populations by reporting sightings to Tony Musante, a wildlife disease biologist with USDA Wildlife Services at (603) 223-6832 or (603) 340-2890.

The goal is to prevent their proliferation, as well as to reduce their population, the damage they cause and disease risks to humans and domestic swine.