The common garter snake (Thamnophis sirtalis) has between two and three yellow, brown or greenish stripes that run down its back. It can sometimes have black spots in between the stripes. It is a small snake that only measures between 18 to 26 inches. The garter snake is found throughout New Hampshire; it is not endangered or threatened.
The brown snake (Storeria dekayi dekayi) is another snake that is not endangered or threatened. It is found throughout the southern portion of New Hampshire. The brown snake has two rows of dark brown or black spots running down the back of its tan to dark brown body. It can be between 10 to 14 inches in length.
The northern red-bellied snake (Storeria occipitomaculata occipitomaculata) and the northern ringneck snake (Diadophis punctatus edwardsii) are common throughout New Hampshire. They are not threatened or endangered. The northern red-bellied snake is small in length, between 8 and 10 inches long. Most of its body is either brown or grey with a bright red belly. Some members of this species have three white spots on the nape of their necks.
The northern ringneck snake is a slender snake between 10 and 15 inches in length. Its body is bluish-black or black with a yellowy underside and a gold ring around its neck. It is found mostly in woody debris or under rocks.
The milk snake (Lampropeltis triangulum triangulum) is found throughout New Hampshire except in the far northern regions.It is not considered endangered or threatened. The milk snake is between 24 and 36 inches in length and has a slender body build with dark splotches. It has a black-and-white checkered belly with a grey back covered with brown or reddish-brown.
The Northern water snake (Nerodia sipedon sipedon) is not threatened or endangered. It is found in aquatic or semi-aquatic areas throughout New Hampshire, except in the far north. It is a thick snake between 24 and 42 inches in length. The Northern water snake is dark in color with numerous black or brown blotches over a grey base. Its belly has black or red half-moon shapes.
The smooth green snake (Opheodrys vernalis) is defined as a threatened species by the New Hampshire Fish and Game Department. This designation means if its numbers continue to decline the green snake will become endangered. It is found throughout New Hampshire and the Isles of Shoals. It is 10 to 20 inches in length and has a very slender in build. The green snake has a bright-green-colored body with a white or pale yellow belly. It is mainly found in grassy fields, pastures and forest openings.
The ribbon snake (Thamnophis sauritus) is one of the snakes considered a threatened snake in New Hampshire. It is a slender snake with three yellow or green stripes running down the length of its body, which normally is 16 to 35 inches long. It can be found throughout New Hampshire near water, except in the far north.
The Eastern hognose snake (Heterodon platirhinos) is considered an endangered species by the New Hampshire Fish and Game Department, which means the department believes if the numbers of this species continue to decline the Eastern hognose could become extinct. It is found in southern New Hampshire along the Merrimack River from Concord to the Massachusetts border. The Eastern hognose is between 20 and 35 inches in length; it is thick-bodied. It has an upturned snout. The hognose's colors change throughout its life. At one stage, the hognose is almost all grayish-black; at another, it is spotted with red or orange spots.
The Northern black racer (Coluber constrictor constrictor) is a threatened species found sparsely through southeastern New Hampshire. It is a snake with a slender body build between 36 and 60 inches in length. The Northern black racers are a glossy black on their back and white on their throat and chin.
Timber rattlesnake (Crotalus horridus) is the only poisonous snake in New Hampshire. It is ranked as a critically imperiled species, which means it is very close to becoming extinct. Currently only one known population exists in New Hampshire, as of 2011. It is a large, thick black snake between 36 and 60 inches in length. The timber rattlesnake has a large blunt rattle at the end of its tail.