Plymouth Redbelly Turtle Habitat Model
go to: USFWS Gulf of Maine Watershed Habitat Analysis
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Draft Date:
February 16, 2001

Species:
Plymouth redbelly turtle, Pseudemys rubriventris

Use of Study Area Resources:
All stages. The species ranges from North Carolina through New Jersey, plus a disjunct population in southeastern Massachusetts. Redbelly turtles in Massachusetts, though not genetically distinctive (Iverson and Graham 1990, Brown 1996), are regarded as a unique population segment (Amaral 1994). The turtle is Federally listed [endangered], with a designated critical habitat encompassing many of the 17 ponds and 1 river site in Plymouth Co. Massachusetts. The study area boundary encompasses about half of these sites. A management program called "headstarting" involves captive hatching and rearing of nestlings for release into know turtle habitats, and for extending the turtle's range.

Habitat Requirements:
"The Plymouth redbelly turtle is a large, freshwater basking turtle of deep coastal plain ponds. It subsists primarily on aquatic vegetation, and requires good water quality and suitable basking, nesting and overwintering sites free from disturbance" (Amaral 1994). The turtle is associated with natural and man-made lakes and pond, surrounded by oak-pine barrens (Endangered Species Information System - ESIS).

In spring females select nest sites in sandy soil, usually within 90 m of the pond, and deposit about 12 eggs (Haskell 1993 in Amaral 1994). In man-modified environments turtles nest in sandy dikes or roadways (ESIS). Hatchlings enter the pond in late summer or overwinter and emerge the following spring. Maturity may require 15 to 20 years (T.E. Graham pers. com. in Amaral 1994). Plymouth redbelly turtles overwinter at the bottom of ponds.

They feed on aquatic vegetation, and also invertebrates such as crayfish (Amaral 1994). Water quality and quantity (to provide appropriate lake water elevations) are essential for maintaining the trophic condition and productivity of turtle food supplies. Nesting sites should be open-canopy to assure adequate solar heating to maintain incubation temperatures for nests. Safe access to nesting sites and migration corridors between ponds also are vital for maintenance of this population.

Habitat Mapping:
Redbelly turtle occurrence information was obtained from the Massachusetts Natural Heritage Program, supplemented by data from the USFWS New England Field Office. Polygon and point data were used to identify lakes at which nesting was known to occur.  Adjacent uplands which may serve as nest areas or travel corridors were selected by buffering lakes 3 cells (90m). A minimum bounding rectangle was constructed around all occurrence locations, and other ponds and adjacent uplands within this vicinity were mapped as potential habitat.  The latter was given approximately half the score of sites known to be used. Habitat scoring is displayed in the following table.

NWI Designations
(wetlands only)
Cover Types

Cover Suitability
(0 - 1 scale)

Known to be used

Cover Suitability
(0 - 1 scale)

Potential use
Upland deciduous forest

0.7**

0.3**
Upland coniferous forest

0.7**

0.3**
Upland mixed forest

0.7**

0.3**
Grassland

1.0**

0.4**
Upland scrub/shrub

1.0**

0.4**
Cultivated
Developed
Bare ground

1.0**

0.4**
PEM, L2EM Lake/pond, emergent vegetation

1.0*

0.5*
PFOcon Palustrine forest, conifer

1.0*

0.4*
PFOdec Palustrine forest, deciduous

1.0*

0.4*
PSSdec Palustrine scrub shrub, deciduous

1.0*

0.4*
PSScon Palustrine scrub shrub, conifer

1.0*

0.4*
PAB, L2AB Lake/pond, aquatic vegetation

1.0*

0.5*
L1UB, PUB Lake/pond, unconsolidated bottom

1.0

0.5
L2US Lake, unconsolidated shore

1.0

0.5
L2RS Lake, rocky shore
R1UB Riverine subtidal unconsolidated
Rper Riverine perennial
E1AB Estuarine subtidal vegetated
E1UB Estuarine subtidal unconsolidated bottom
E2AB Estuarine intertidal algae
E2EM Estuarine intertidal emergent
E2RS, R1RS Estuarine, tidal river rocky shore
E2SS Estuarine intertidal shrub
E2US Estuarine intertidal unconsolidated shore
M1AB Marine subtidal vegetated
M1UB Marine subtidal unconsolidated bottom
M2AB Marine intertidal algae
M2RS Marine intertidal rocky shore
M2US Marine intertidal unconsolidated shore
NOTES *score as aquatic habitat, if within 90 m of ponds
**score for nesting, if within 90 m of ponds

These scores reflect our relative confidence in suitability of the habitat, and also allow the specific used and potential habitats to be distinguished on the maps.

Sources:
Amaral, M. 1994. Plymouth Redbelly Turtle (Pseudemys rubriventris) Recovery Plan, second revision. USFWS, Hadley, MA. 39 p.

Brown, R.A. 1996. Genetic variation among populations of the redbelly turtle (Pseudemys rubriventris). Copeia 1:192-194.

Endangered Species Information System. Fish and Wildlife Information --VA Tech. http://fwie.fw.vt.edu/WWW/esis/lists/e155001.htm

Iverson, J.B. and T.E. Graham. 1990. Geographic variation in the redbelly turtle, Pseudemys rubriventris (reptilia: testudines). Annals of Carnegie Museum 59(1):1-13.