A pedestrian spotted a live 21/2-foot-long boa constrictor on a Nuuanu Avenue sidewalk Tuesday morning.

The nonvenomous rainbow boa constrictor was seen on the sidewalk in front of the Kukui Plaza condominium at about 7 a.m., captured and turned over to police, the state Agriculture Department said.

Department officials said rainbow boas are native to Central and South America and can grow up to 6 feet long. In the wild their diet consists of rodents, birds, lizards and aquatic animals.

Snakes are illegal to possess and transport in Hawaii. They pose a serious threat to Hawaii’s environment because they have no endemic natural predators here and because they would compete with native animal populations for food and habitat.

The state offers amnesty to anyone who reports the whereabouts of snakes kept illegally as pets. They may be turned in at any Department of Agriculture office, the Honolulu Zoo, Panaewa Zoo in Hilo or any Humane Society without fines or prosecution.

In June 2010 the owner of a 9-foot reticulated python that was being kept in a Waianae garage took advantage of the amnesty law after initially trying to donate the snake to the Honolulu Zoo. Reptile handlers from the zoo and two department inspectors took the snake, which was later shipped to a reptile farm on the mainland.

Reticulated pythons, native to Southeast Asia, the Philippines and Indonesia, can grow up to 30 feet long and weigh more than 250 pounds.

The maximum penalty under state law for possessing and/or transporting illegal animals, a Class C felony, is a $200,000 fine and up to three years in prison.

Snakes periodically pop up in Hawaii and prompt quick action.

In July a family staying in a Kona condo found a 16-inch garter snake in the unit shortly after unpacking. Authorities speculated that the snake may have hitchhiked a ride in the family’s luggage.

In May a foot-long juvenile ornate tree snake was captured at Joint Base Pearl Harbor-Hickam in a maintenance bay near the airfield.

To report a snake, call the state pest hotline, 643-7378.