Plymouth Redbelly Turtle
Pseudemys rubriventris
***Description:***1
The redbelly turtle is a large 26-32cm (10-12in) variably patterned basking turtle that can weigh up to 4.5kg (10 pounds). The carapace (top shell) of an adult redbelly is generally black to mahogany colored with light chestnut to red markings along the margin. The plastron (bottom shell) of the males is pale pink overlaid with dark mottling, while the females have red plastrons with borders of grey along the seams of the shell plates. The ground color of the head, neck, limbs and tail is black, marked with yellow or ivory lines. Males have shorter shells and longer tails and front claws than females. In old males, scales on the legs and lines on the soft parts often turn dull red, and males usually become progressively melanistic (blacken) with age.
A wild, unmarked adult female Redbelly basking with Painted turtles at a newly discovered site in Plymouth County, Massachusetts. Note the size difference between the two species.
Another wild, unmarked adult female from the same site, disturbed from her basking site by the photographer’s boat.
Hatchlings are about 2.5cm (1 inch) long and are more circular in shape than adults. They have a slightly keeled light green carapace marked with orange bars and greenish yellow hieroglyphics, and light green circular spots along the perimeter of the underside of the carapace. The head, neck, limbs and tail of hatchlings are green but transform to brown and then black over a two year period. Like adults, juveniles have yellow stripes on the head, neck and limbs.
Plastral view of hatchling Redbelly turtle (P. rubriventris) showing remnants of egg yolk.
A group of hatchlings dug from a marked nest in November 1997. Notice the identification notches on the margin of the carapace.
Carapacial view of hatchling Redbelly turtle (P. rubriventris) showing distinctive markings uncharacteristic of other New England turtle species.
1From the Natural Heritage & Endangered Species Program’s Redbelly Turtle Endangered Species Fact Sheet
Similar Massachusetts species:
In Massachusetts, the only other chelonian usually mistaken for a redbelly turtle is the painted turtle, also known locally as the “sun turtle”, from their habit of basking atop logs and rocks for extended periods on sunny days. The markings of the two species are similar with the notable exceptions of carapace color, facial markings, size and plastral color. Painted turtles have a slate grey or olive black carapace, while redbelly turtles have a mahogany colored carapace which is flattened in the middle and longer and broader than the Painted turtles. Painted turtles posess a large yellow spot on the side of the face which the redbelly turtle lacks. The redbelly turtle also has a prominent notch at the tip of the upper jaw flanked by cusps along each side and an arrow-shaped stripe running atop the head between the eyes to the snout and a reddish plastron with dark markings along the margins. The painted turtle has no cusp and no arrow-shaped stripe and the plastron is usually clean orange or yellow, with some striping along the perimeter. Redbelly turtles also tend to inhabit more remote ponds, and are much less tolerant of human disturbance than painted turtles.
Range and Habitat:
Redbelly turtles in Massachusetts are only known from ponds within Plymouth County (Plymouth, Carver and Kingston). The population distribution of the Redbelly turtle is from the coastal plain of New Jersey south to North Carolina and inland to West Virginia. Formerly known as P. rubriventris bangsi, the Massachusetts population was thought to be a distinct subspecies. In 1990, research confirmed that the subspecific designation was not valid and that the two populations were disjunct with no subspecies.
In Massachusetts, the Redbelly turtle is a denizen of freshwater ponds of varying sizes and depths with an abundance of aquatic vegetation. Further south, this turtle usually inhabits river systems. Sandy soil on land surrounding the pond or river is required for nesting.
Biology:
The Redbelly turtle feeds primarily on aquatic vegetation, particularly milfoil. Crayfish and invertebrates may be taken in the first few years of life. Females reach maturity at eight to fifteen years of age and males at four to six. Sexual dimorphism is apparent at five to seven years. Redbelly turtles may live as long as 40 to 55 years.
Females may begin nesting activity in June or July. Usually, nests are located within 100 yards of the pond and are usually located approximately one meter above the pond level. Redbelly turtles will utilize both vegetated and unvegetated areas for nesting as well as both disturbed and undisturbed substrates. Nests are usually between five to seven inches deep, depending upon the degree of difficulty associated with digging, the size of the female and the degree of disturbance of the female during nest digging. The usual clutch is from 10-20 eggs and incubation may last from 73-80 days if the temperature remains consistently at 25 degrees Celsius. Hatchling emergence usually occurs from late August through October and is governed more by substrate conditions, temperature consistency, rainfall and nest site location than by egg deposition by the female. Females may lay a second clutch in the fall and these hatchlings usually overwinter in the nest and emerge in the spring.
Massachusetts population status:
The Massachusetts population of the Redbelly Turtle is listed as an endangered species by the Massachusetts Division of Fisheries & Wildlife and the U.S. Fish & Wildlife Service. There are approximately 300 breeding age individuals known to exist in this population. Redbelly Turtles are specialists with certain physiological requirements that make it vulnerable to the effects of environmental changes such as housing construction, which has altered the turtles habitat by reducing the amount of available nesting areas and also by homeowners proclivity for eliminating aquatic weed growth by the use of herbicides which alters the food source of this turtle. In the past, the land around these ponds was periodically subjected to burning, which created pitch pine/ scrub oak forests interspersed with open areas and grasslands. The openings around the ponds perimeter allowed sunlight to incubate eggs more efficiently. Today, these areas are developed and protected against fire. As a result, closed-canopy forests tend to predominate in these areas, blocking out the sunlight needed to incubate the turtle eggs. Residential dwellings also bring about an increase in mammalian predators such as raccoons, opossum and domestic pets as well as additional human harassment, collection, vandalism and road mortality.
Species management:
Habitat preservation, education, sound management and continued research are seen as important aspects of the successful management of the Plymouth Redbelly Turtle. Research into the deleterious effects of pesticide, herbicide and heavy metal contamination on existing populations is important to the survival of this species. Existing populations need to be monitored to note any changes or potential threats to the population, potential population sites need to be evaluated as to the existence of this species and formerly occupied sites need to be investigated to determine if this species has returned or could possibly be reintroduced to the site in the future. Efforts to reduce mortality of hatchlings and incubating nests need to be implemented, either by enclosing discovered nests with wire mesh enclosures as has been successfully done in the past, or by trapping and removing predatory mammals. Habitat preservation and improvement is an important tool for the continued viability of this species. Occupied habitat needs to be protected and altered habitat needs to be improved by clearing or creating nesting areas and open egg-laying areas as well as basking sites where needed.
Education and law enforcement are also important management tools. The laws protecting this species need to be widely publicized and enforced as needed. The cranberry and other agricultural industries in Massachusetts need to work more closely with biologists in order to avoid potentially damaging activities. Education of the public and private landowners to increase awareness of this turtles needs and problems is also needed in order to protect this species.
The Plymouth Redbelly Turtle Headstart Program dates back to 1985 when, under the direction of Dr. Thomas French of the Natural Heritage and Endangered Species Program, a number of hatchlings were recovered from protected nests in Plymouth County and turned over to several scientific institutions for rearing during the winter months when these animals would normally be hibernating. The goal was to get these turtles to a decent size (between 4-5inches in length) before releasing them back into the wild. At this size, predation becomes less of a factor and these animals have a “headstart” towards a long and reproductive life. The program has produced hundreds of these headstarted juveniles and has successfully reintroduced these turtles back into their ponds of origin. The latest round of headstarting began in early October of 1997 under rather unusual circumstances. Usually, nests are covered with wire mesh and the young are recovered from these enclosures when they emerge from the nest. In this instance, it was thought that the mortality rate of so called “late-season” hatchlings could be improved by headstarting.
Late season hatchlings are those which overwinter in the nest until their emergence in springtime. As stated earlier, a female may lay a second clutch in August or early September and these eggs would hatch out in approximately 70-90 days and the hatchlings will remain underground for the remainder of the winter which in New England, may last until the beginning of April. These late season nests were marked and the hatchlings were dug from them by Dr. Terry Graham, a biology professor at Worcester State College who focused the attention of the U.S Fish & Wildlife Service on this species as well as the man who pioneered the headstart program for this species. From this effort, a total of 32 live hatchlings were recovered. Dr. Graham held these turtles for a period of several weeks to enable the turtles to absorb the large yolk sacs attached to their plastrons.
It was decided by Dr. French that the New England Herpetological Society would be the repository for these hatchlings. A team of cooperators was assembled by Kurt Schatzl, then President-Elect of the NEHS which would facilitate the rearing of these turtles from November of 1997 until May of 1998 when the headstarted juveniles would be turned over to the MA Division of Fisheries & Wildlife for reintroduction into the wild.
Due to the enormous size attained by these turtles as well as the large amount of food that would be consumed, only two or three hatchlings were assigned to each of the 14 individuals involved in the program. The minimum housing requirements for these turtles during this six month time period would be a 20 gallon long aquarium with an excellent filtration system which can be utilized optimally at all water levels, a spotlight and Vita-LiteTM for basking and an adequate amount of romaine and red leaf lettuce, which is the primary diet consumed by these turtles in captivity.
To date, several hundred redbelly turtle hatchlings have been successfully reared by New England Herpetological Society cooperators and released back into the wild as headstarted juveniles. This is an ongoing project between the NEHS and the Massachusetts Division of Fisheries & Wildlife.