Terry Day, who has lived in her Manoa home for 30 years, had never seen a feral pig in her yard until last year.

"I ignored it for a while," Day said. "Now the pigs are not only denuding the area around my yard, they are doing it all around the neighborhood. There are tons more pigs than there used to be."

Day lives along the edge of the state's conservation land below Wa'ahila Ridge. Two months ago she had hunters remove several pigs from her property, hoping that would solve the problem, at least temporarily. But the wild beasts are back.

"There is nothing left in the way of any greenery back there," she said. "When it rains, it sends mud and rocks down the hill."

To tackle the problem, the state is considering a return to a regular pig-hunting season that would offer three months of open hunting followed by a three-month hunting hiatus to increase the annual kill. The state now has sporadic open hunting for pigs.

State records show that the number of wild pigs killed on O'ahu grew from 200 in fiscal 1999 to 294 in fiscal 2002. Those numbers only include pigs killed in hunts on public lands, not on private property, where many pigs are taken.

The kill rate dropped slightly over the next two years, but is on a record pace this year, with 158 pigs killed since the fiscal year started July 1.

Conservation groups and state officials also are concerned that recent growth in the feral pig population on O'ahu is sending the animals into existing urban areas in search of food and is damaging the watershed.

"Certainly feral pigs have a huge ability to reproduce," said Sam Gon III, a cultural expert and scientist with the Nature Conservancy. "It is no surprise that where our urban centers go right up against forestry they come into people's gardens."

When a resident calls the state to report a pig problem, he or she is often referred to the O'ahu Pig Hunters Association, which has a permit to allow its hunters to trap or shoot pigs.

The state supports this effort by supplying some traps to the association, but the work is voluntary.

Cory Vidinha, 30, is a third-generation pig hunter who lives in Palolo. He volunteers to remove pigs causing problems in residential areas from Hawai'i Kai to Manoa. On Saturday, he went to St. Louis Heights to check some traps set behind a home on Peter Street where pigs were tearing up the yard.

Vidinha checks his rope snares every day to make sure that if an animal is caught it is not left hanging for too long.

If a large sow or boar is caught, he will take it for food, making kalua pig, sausage or smoked meat. If the pig is young or pregnant, he will take it back into the mountains away from homes and release it.

Vidinha warned that pigs are dangerous in the wild and if one were to attack, the best escape is to climb a tree.

"They are like any other wild animal," he said. "They won't attack you just to attack you, but if they are cornered or threatened, they will tear you up."

Because the pigs live in such remote areas, the state says it is impossible to come up with an accurate count of their population, but calls reporting pigs in residential areas from Manoa to Nu'uanu to Kane'ohe have increased in the past year.

"I haven't heard of any huge increase, but based on the number of calls, it is tending to move in that direction," said Ed Johnson, wildlife biologist and state hunting coordinator with the state Department of Land and Natural Resources. "Urban areas just keep expanding into rural and natural resource areas and that is going to expose more homes to pigs. If there are already pigs in remote areas and they continue to reproduce, the new ones have to find new home ranges to occupy so they will spread."

Pigs can have one or two litters a year, with up to 10 piglets per litter, he said.

Pascual Dabis, president of the pig hunters group, said there has been an increase this year in the number of requests for help.

"The majority of the pigs are on the edge of conservation land," Dabis said. "They go down and scavenge fruits or heliconia, uprooting it looking for worms. Or they turn over the garbage container."

The Nature Conservancy's Gon said pigs are rooters that rip up the ground in search of food.

"They can do an amazing amount of upturning of ground," Gon said. "Go to a yard that has been visited by a pig and it looks like it has been Roto-tilled. You have a foot-deep plowing all through the yard."

On a larger scale, the increasing pig population is damaging the watershed, he said. A watershed is a land area, such as a mountain or valley, that catches and collects rainwater, which recharges underground water supplies and also sends clean water into streams.

The state and conservation groups spend millions to protect native plants and animals from the effects of feral pigs, Gon said, including building fences around entire tracts of land.

Reach James Gonser at jgonser@honoluluadvertiser.com.