The Northern Diamondback Terrapin Turtle: A Species of concern Protected by an Orenda sanctuary

Smith's Dock Sanctuary, which is part of the Great Salt Marsh in West Barnstable, is home to the Northern Diamondback Terrapin Turtle. This Orenda sanctuary is one of just 17 places within Massachusetts where these turtles can be found. The diamondback lives and breeds in salt marshes and tidal tributaries and is the only North American turtle that lives exclusively in brackish water. They prefer unpolluted tidal areas and therefore are good indicators of healthy wetland systems.

The diamondback may live as long as 50 years, which is important considering their low hatchling survival rate. Although mating occurs in May, female terrapins store sperm and thus can produce fertilized eggs up to four years after mating. In June and July, females lay an average of 13 light pink and leathery textured eggs in nests on shore in sand or loam, then cover them. Hatching occurs from August through October, depending on temperatures. The sex of hatchlings is determined by the temperature of the nest; a higher nest temperature produces more females while a lower temperature produces more males. When the hatchlings emerge, they are only an inch long and must survive on their own. Only 1-3% of the eggs that are laid produce a hatchling. The percentage of survivor hatchlings in the wild is currently unknown but is believed to be equally as low. Hatchlings are a favorite meal of herons.

A male terrapin is considered mature by seven years old, weighing about a pound and measuring four inches long. The female terrapin matures later -- at twelve years old -- and can weigh up to seven pounds, reaching lengths of nine inches long. Water temperatures and food supply play a role in growth rates. In warmer waters terrapins stay active, feed longer and hibernate less.

The terrapin, as with all turtles, has a strong beak rather than teeth. It is a predator more than a scavenger. However, unlike the aggressive snapping turtle, the terrapin can be quite docile. The top shell may be light brown, bluish gray or black, while the underside is yellow to olive in color. The outside of the top shell is covered with thin, shiny scales that have black concentric rings, earning them the name "diamondback." Diamondbacks are strong climbers and have webbed feet enabling them to swim fast.

Studies have shown that adult terrapins tend to remain in a rather small area for most of their lives. The Smith's Dock sanctuary is an especially critical habitat for these turtles because terrapins stay close to their natal beaches and are not likely to repopulate in other areas on their own.

Compiled with information from: Maryland Department of Natural Resources

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