This Northern Water Snake (Nerodia sipedon) is hunting along the edges of a marsh in Great Meadows National Wildlife Refuge in Concord, Massachusetts. This a large, nonvenomous, common water snake native to North America and can grow up to 135 cm (4 ft 5 in) in total length. In the wild, adult females generally weigh between 158.9 and 408 g (5.61 and 14.39 oz) while the smaller male averages from 80.8 to 151 g (2.85 to 5.33 oz). The largest females can weigh up to 560 g (20 oz) while the largest males can weigh 370 g (13 oz). The coloration of the Northern Water Snake is quite variable (brown, gray, reddish, or brownish-black) and they darken with age. Some individuals, as shown here, can become almost completely black. The belly of this snake also varies in color including white, yellow, or gray - usually with reddish or black crescents.
The Northern Water Snake is found throughout eastern and central North America, from southern Ontario and southern Quebec in the north, to Texas and Florida in the south. They are active during the day and at night. During the day, they hunt among plants at the water's edge, looking for small fish, frogs, worms, leeches, crayfish, salamanders, small birds and mammals. At night, they concentrate on minnows and other small fish sleeping in shallow water. They hunt using both smell and sight.