The northern red-bellied cooter (Pseudemys rubriventris pop.) is endemic to ponds in eastern Massachusetts . It formerly occurred in a patchy distribution in most of the state's coastal counties including Essex, Middlesex, Plymouth, Barnstable, and Dukes. The only non-coastal county with a historical record is Worcester. Today it occurs only in Plymouth County.
Due to the loss of historic populations, increasing shoreline and between-pond development, and increased predation pressure, the northern red-bellied cooter was placed on the endangered species listed and granted critical habitat in 1980 . Twelve occupied ponds were known at the time. Three additional populations, including Federal Pond, were discovered in subsequent years. Federal Pond was and is the largest population. An active "headstarting" program introduced the cooter to ten additional ponds and two rivers by 2005 [2, 3, 4]. All nests discovered each year are caged to protect the eggs and hatchlings from predators (about 95% of uncaged nests suffer predation) . When hatching is complete, 50% of the hatchlings are released into the same pond and 50% are moved to headstarting facilities which raise them to a size that is less vulnerable to predation. The headstarted turtles are reintroduced to the same or new sites. Between 1985 and 2005, the program released over 2,500 turtles [3, 4]. Headstarted turtles were first documented to breed in the wild in 2000 .
Due to the difficulty of censusing the species, quantitative population trend data have not been gathered . However, species experts are in agreement that the number of occupied sites and the number of individuals has increased in size since 1980, primarily due to the headstarting program and to a lesser extent natural reproduction [2, 4]. The 1994 federal recovery plan requires a total of at least 600 breeding-age turtles distributed among at least 15 self-sustaining populations for downlisting to be considered . Delisting will require at least 1,000 breeding-age turtles in 20 or more self-sustaining populations.
When listed as an endangered species, the taxon was called the "Plymouth red-bellied turtle" and was considered a subspecies (Pseudemys rubriventris bangsi) . The subspecies has since been invalidated, but the 1994 federal recovery plan explains that as an ecologically and geographically distinct population, it still qualifies as an endangered species. The nearest individuals of the southern population are 250 miles away in southern New Jersey. The northern population is also unique in only being found naturally in ponds. The southern population is often riverine. The taxon's status as an endangered species will be reviewed in 2006 in response to a delisting petition [2, 5].
 U.S. Fish and Wildlife Service. 1994. Plymouth Redbelly Turtle (Pseudernys rubriventris) Recovery Plan, Second Revision. U.S. Fish and Wildife Service, Hadley, Massachusetts. 48 pp.
 Amaral, M. 2006. Personal communication with Michael Amaral, U.S. Fish and Wildlife Service, Concord, NH, February 7, 2006.
 Amaral, M. 2006. Released northern red-bellied cooters, 1985-2003. Spreadsheet provided by Michael Amaral, U.S. Fish and Wildlife Service, Concord, NH, February 7, 2006.
 French, T. 2006. Personal communication with Tom French, Massachusetts Natural Heritage and Endangered Species Program, Westborough, MA, February 7, 2006, and February 8, 2006.
 Gordon, R. 1997. Petition to Remove the 'Plymouth Redbelly Turtle' ('Pseudemys rubriventris bangsi') from the List of Endangered and Threatened Wildlife and Plants. National Wilderness Institute, February 3, 1997.