Ringed Map Turtle (Graptemys oculifera) Surveys on the Pearl River

Washington Parish

Keri Landry, Biologist Louisiana Natural Heritage Program Louisiana Department of Wildlife and Fisheries

Introduction

Ringed map turtles (Graptemys oculifera) are endemic to the Pearl River and its tributaries in Mississippi and Louisiana in stretches with moderate current, sand beaches, and abundant basking structures. The LDWF conducted a basking survey during 2009-2010 along the Bogue Chitto River in Louisiana, a tributary of the Pearl River, which showed a decline in ringed map turtle numbers over the past decade. Periodic surveys within this river system are necessary to evaluate population trends. For the current project, mark-resight techniques were used along the northern stretch of the Pearl River in Washington parish. The Pearl River map turtle, Graptemys pearlensis (formerly known as Pascagoula map turtle, Graptemys gibbonsi) is also endemic to the Pearl River and its tributaries in Louisiana and Mississippi and the status of this species was also assessed during this project. Nesting areas were assessed along the Pearl River survey sites. Issues were documented such as ATV use on sandbars, sand and gravel mining, invasive species and other activities detrimental to nesting turtles.

Goals

• Obtain population estimates of the ringed map turtle on the Pearl River • Assess quality and amount of available nesting habitat • Assess quality and amount of basking/foraging sites • Update LNHP database with current locality data for this species • Address issues with activities detrimental to nesting turtles

Survey Methodology

Trapping

Surveys were conducted along two stretches of the Pearl River, north and south of the Bogalusa public boat launch in Washington Parish during October 2011, May and October 2012 to assess current status of G. oculifera and G. pearlensis (Figure 1). A 16-foot aluminum Jon boat with 25Hp motor was used to peruse the river to monitor structures, such as logs and branches, for basking turtles particularly Graptemys spp. Once basking structures were selected, various sizes of open-topped basking traps made of crawfish wire were attached to logs and branches with nails and cotton twine and slightly submerged to conceal the trap from basking turtles. Approximately 10-13 traps were used during each trapping period and when possible, turtles were also captured by hand using a dip net. Logs and branches with basking traps were monitored frequently for turtles. Captured Graptemys species were identified, weighed, measured, and permanently marked. Individuals were also temporarily marked on the 2nd and 3rd vertebral scutes with a waterproof, tree-marking spray paint (Aervoe® Lead- Free Fluorescent Glo Spray Paint, Aervoe Industries, Inc.) for mark-resight surveys. G. oculifera were marked with fluorescent orange and G. pearlensis were marked with fluorescent green spray paint to distinguish the species. Tail clips were also collected for subsequent genetics analysis. Turtles were then released at their capture location.

Resight Survey

Resight surveys were conducted on May 31st, June 26-27th, and October 24th, 2012 within optimal conditions for basking turtles and along the river stretches that were surveyed with traps. Resight surveys began after at least 10 turtles were paint-marked to ensure an adequate number of marked turtles were available for surveys and 2-3 weeks after the first turtle was marked to ensure no loss of paint marks. Biologists began at the upstream end of sandbars and scanned basking structures with a pair of 10x40 binoculars and a spotting scope with 20-60x zoom eyepiece mounted on a tripod. Data collection included number of marked and unmarked turtles, species, age classes (adult, juvenile), and gender if feasible. Shively (1999) recommended that surveys not be conducted during late summer because basking rates are expected to decrease when water temperatures rise too high; therefore, surveys in 2011 and 2012 ceased by the end of June until October.

Nest Survey

Nest surveys were conducted on sandbars within the survey area south of the Bogalusa public boat launch on the Pearl River on August 1st, 2012. Transects were conducted across the entire area of each sandbar in search of tracks and nests. All tracks were identified and noted as well as the number and condition of nests.

Results

Trapping

The total length surveyed for basking turtles is approximately 10 river kilometers (rkm); a 6 rkm stretch north of Bogalusa and a 4 rkm stretch south of Bogalusa (Figure 2). A total of 28 turtles were marked during this survey effort; 26 G. oculifera and two G. pearlensis (Table 1). Approximately 77 percent of all G. oculifera captured during surveys were adults and adults accounted for 75 percent of the total for all captured species. There was nearly a 1:1 ratio when comparing captures of males to females. The two captures with unknown gender were due to the individuals being too young to determine gender. Other species caught in traps were Pseudemys concinna (river cooter), Trachemys scripta (red-eared slider), Apalone spinifera (spiny softshell), and Sternotherus carinatus (razor-back musk turtle).

Resight Survey

The most common species observed basking was G. oculifera, accounting for approximately 82 percent of the total number of individuals (Table 2). The total number of G. oculifera captured was divided in gender by 57 males and 26 females with 30 individuals noted as unknown for gender due to limitations while surveying. One paint- marked male G. oculifera was observed basking during resight surveys. One female G. pearlensis was observed and only 3 unidentified Graptemys and 2 unidentified turtles were included in the total count of turtles for this survey effort. Nest Survey

Many turtle tracks and several nests were observed while walking transects. Tracks were followed to find potential nests. A total of 22 nests with egg shells remnants, either intact or pieces, were counted during this survey. Eight of these nests were nearly absent of egg shells and appeared to be depredated. Other tracks observed while nest searching include human, feral hog, raccoon, opossum, deer, vulture, turkey, and wading bird.

Discussion

Due to multiple boat motor issues and the labor intensive nature of this project, additional trapping and mark-resight surveys are necessary to completely assess the population status of these turtles. Evidence of reproduction was observed during the 2012 surveys, although more time should be given to nest searching. Additional nest surveys will be conducted to determine the amount of available and occupied nesting habitat and nest success of Graptemys species. Environmental and habitat data will be collected during future surveys to assess basking site availability and examine environmental and habitat trends. Locality data entry into the LNHP database will be completed by spring 2013.

Issues such as ATV use on sandbars, sand and gravel mining, invasive species and other activities detrimental to nesting turtles should be addressed by coordinating with LDWF scenic rivers, other agencies and by providing technical assistance to private landowners in key areas. As evidenced from nesting surveys, feral hogs may be a serious issue for nesting turtles along the Pearl River and will be examined further in the future.

Recommendations

• The Pearl River system is designated as a Natural and Scenic river under the LDWF Scenic Rivers Program; therefore, it is protected from clearing or snagging. Continue to use Best Management Practices for Streamside Management Zones to protect exposed sandbars and maintain deadwood for basking sites.

• As required by the ringed map turtle recovery plan for delisting there should be evidence of increasing populations within the Pearl River System and its tributaries over a 10 year period. Conduct periodic surveys to monitor population trends.

• Minimize anthropogenic changes in river hydrology, which limits the availability of exposed sandbars, and causes decreased water quality, to prevent further declines in current populations. Conduct all work as necessary to minimize impacts such as heavy runoff and siltation.

• Nest surveys should be conducted to determine the amount of available and occupied nesting habitat. Landowners should be notified of any observed activities that are detrimental to nesting turtles. Nest surveys provide vital information which would be beneficial in protecting these Graptemys species. Future projects should include an assessment of habitat type and basking site availability and document disturbance or change in flow.

Acknowledgements

The U.S. Fish and Wildlife Service provided Section 6 funding in support of this survey effort. Will Selman (LDWF- Rockefeller NWR), Randy Wiggins and Beau Gregory (LDWF-LNHP), and Jeremy Miller (LDWF- Marine Fisheries) assisted with surveys. Joe Nehlig with Lee Memorial Forest provided housing during extended field days. Tim Ruth with LDWF-Inland Fisheries provided the use of their boat.

References

Dickerson, D. D. and K. J. Reine. 1996. Habitat assessment and relative abundance estimates for the ringed sawback turtle (Graptemys oculifera) in dredging sites of the West Pearl River Navigation Project (Louisiana): Final Project Report. U.S. Army Engineer District, Vicksburg. 21 pp. plus tables, figures and appendices.

Ennen, J. R., J. E. Lovich, B. R. Kreiser, W. Selman and C. P. Qualls. 2010. Genetic and Morphological Variation Between Populations of the Pascagoula Map Turtle (Graptemys gibbonsi) in the Pearl and Pascagoula Rivers with Description of a New Species. Chelonian Conservation and Biology 9(1): 98–113.

Jones, R. L. and P. D. Hartfield. 1995. Population size and growth in the turtle Graptemys oculifera. Journal of Herpetology 29:426-436.

Jones, R. L. and W. Selman. 2009. Graptemys oculifera (Baur 1890)- ringed map turtle, ringed sawback. In: Rhodin, A.G.J., Pritchard, P.C.H., van Dijk, P.P., Saumure, R.A., Buhlmann, K.A., Iverson, J.B., and Mittermeier, R.A. (Eds.). Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Monographs No. 5, pp. 033.1-033.8, doi:10.3854/crm.5.033.oculifera.v1.2009, http://www.iucn-tftsg.org/cbftt/.

Lindeman, P. V. 1999. Surveys of basking map turtles Graptemys spp. in three river drainages and the importance of deadwood abundance. Biological Conservation 88: 33-42

Selman, W. and C. Qualls. 2009. Distribution and abundance of two imperiled Graptemys species of the Pascagoula river system. Herpetological Conservation and Biology. 4(2):171-184.

Shively, Stephen H. 1999. 1999 Survey for the ringed map turtle (Graptemys oculifera) in the Bogue Chitto River, Louisiana. Section 6 project report to the U.S. Fish and Wildlife Service by the Louisiana Natural Heritage Program. 12pp. plus tables and figures.

U.S. Fish and Wildlife Service. 1988. A recovery plan for the ringed sawback turtle Graptemys oculifera. U.S. Fish and Wildlife Service, Atlanta.

Figure 1. Map turtle trapping area (depicted by the yellow line) on the Pearl River near Bogalusa, LA in Washington parish.

Figure 2. Trapping sites on the Pearl River (depicted by yellow line), north and south of Bogalusa in Washington parish during the 2011-2012 survey period.

Table 1. Number of individual turtles, gender and age class per species trapped and marked during surveys of the Pearl River near Bogalusa, Louisiana.

Number Gender Age Class Species Marked Male Female Unknown Adult Juvenile

G. oculifera 26 12 13 1 20 6

G. pearlensis 2 1 0 1 1 1

Total 28 13 13 2 21 7

Table 2. Number of individual turtles, gender, and age class per species observed during re-sight surveys on the Pearl River near Bogalusa, Louisiana.

Number Species Gender Age Class marked turtles Adult Juvenile male 57 n/a 1

G. oculifera female 26 n/a 0

unknown 30 8 0

male 0 n/a 0

G. pearlensis female 1 n/a 0

unknown 0 n/a 0

Pseudemys n/a 18 n/a 0

Apalone n/a 4 n/a 0

Sternotherus n/a 1 n/a 0

Total n/a 137 8 1

Adult male G. oculifera in the Pearl Adult male G. pearlensis in the Pearl River, Washington Parish, south of River, Washington Parish, south of Bogalusa, Louisiana. Bogalusa, Louisiana.

Basking trap secured and hanging on a Basking trap secured on a log with nails medium-sized log used to capture used to guide turtles into the trap. basking turtles.