Loggerhead Turtle Nesting in Georgia, 2008.

Transcription

1 Loggerhead Turtle Nesting in Georgia, Mark G. Dodd and Adam H. Mackinnon Georgia Department of Natural Resources Nongame Conservation Section One Conservation Way, Brunswick GA Annual Report submitted to U.S. Fish and Wildlife Service for grant E-5- Amendment 8 Coordination of loggerhead sea turtle nest protection in Georgia 43 pp.

2 Introduction The loggerhead turtle (Caretta caretta) was listed as threatened under the Endangered Species Act of 1973 as a result of declines in nesting in the southeastern United States and high mortality rates associated with commercial fishing activity. The Recovery Plan for the Northwest Atlantic Population of Loggerhead Turtle Caretta caretta (NMFS-USFWS, 2008) delineates reasonable actions required to recover and/or protect loggerhead turtle populations. Monitoring nesting activity is considered a high priority action and is necessary to evaluate population status and the effectiveness of nest protection measures. In this report, we present an overview of loggerhead turtle nesting in Georgia during Sea turtle research and management programs were first established in Georgia on Little Cumberland and Blackbeard Islands in 1964 and 1965, respectively. In the early 1970 s, additional nest protection projects were established on Jekyll and Wassaw Islands. As concern grew over the status of loggerhead turtle populations, the Georgia Department of Natural Resources (GADNR) initiated a program to monitor loggerhead nesting activity on all major nesting beaches. By 1989, all barrier islands, with the exception of Wolf, Pine and Little Tybee Islands, had nest protection and monitoring programs in place. Management and protection activities have varied considerably among projects and years. Management activities have ranged from little or no manipulation of loggerhead nesting, to relocation of a large number of nests, non self-releasing hatcheries, and predator control. Research activities have included saturation tagging efforts, studies of adult female reproductive physiology and fecundity, and the monitoring of inter-nesting and post-nesting movement patterns. In 1994, Georgia s island managers adopted the Georgia Loggerhead Recovery and Habitat Protection Plan (GLRHPP) which has standardized procedures for nest management in the state. The GLRHPP is similar to the Federal recovery plan, but addresses issues specific to the state of Georgia. Methods Survey Methodology Managing loggerhead turtles in Georgia is a collaborative effort. GADNR coordinates a group of volunteers, researchers, and government employees that conduct nest protection and management activities on Georgia beaches (Table 1). This group is known collectively as the Georgia Sea Turtle Cooperative. During 2008, cooperators conducted daily surveys of all barrier island beaches (Fig. 1) with the exception of Little Tybee/Williamson Island, Pine Island, Wolf Island, and middle beach and southwest beach/ St. Catherines Island which were surveyed opportunistically. The protocols for daily surveys include: 1) surveys must be initiated between May 1- May 15 and continued through the end of the nesting season (August 31), 2) surveys must be conducted daily although 2

3 1-2 days may have been missed due to logistical difficulties, and 3) survey area must be standardized throughout the length of the study, although we allowed for small annual changes in beach profiles (+ 0.5 km). On most beaches, cooperators conducted surveys at dawn unless access was restricted by high tides (Table 1). Cooperators surveyed nesting habitat by truck, ATV, bicycle, or on foot, monitoring for signs of loggerhead turtle nesting activity. When an emergence was located, observers used field signs (presence of a body pit and thrown sand) to determine if the emergence was a nest or nonnesting emergence. Cooperators confirmed the presence of eggs by probing with a blunt dowel or digging by hand to locate the egg chamber. Cooperators marked each nest with a wooden stake. If observers suspected that a turtle nested, but could not locate a nest cavity, the emergence was categorized as an unknown. Cooperators marked and monitored unknowns through the nesting season. If no hatch was observed, the emergence type was re-categorized as a non-nesting emergence. Observers recorded the date, time, and location (latitude and longitude) of all emergences using a hand-held GPS receiver. Cooperators categorized non-nesting emergences as above or below the previous night s high tide. On Wassaw, Blackbeard, Jekyll and Little Cumberland Islands, cooperators collected nesting data during nightly patrols associated with saturation tagging activities (Table 1). Standardized daily surveys were not conducted on Little Tybee/Williamson, Pine, and Wolf Islands because of historically low loggerhead nesting densities and the logistical difficulty conducting surveys. Cooperators generally visited these sites fewer than three times during the nesting season. Cooperators relocated all nests deposited below the spring tide line (low beach elevation) to higher beach elevations to minimize the effects of tidal inundation on embryo development. However, cooperators were asked by GADNR to view nest relocation as a management tool of last resort; only nests in danger of frequent inundation were to be moved. Cooperators relocated nests to a nearby dune with a vegetation-free seaward facing slope. Cooperators attempted to move all nests within 12 hours of deposition (prior to 10:00 am the following morning). Observers were careful to maintain the vertical orientation of the eggs during transport. For each relocated nest, observers recorded the date, time, and location (latitude and longitude) using a GPS receiver. Nest protection protocols and survey effort varied between islands (Table 1). On most undeveloped islands, including Wassaw, Ossabaw, St. Catherines, Blackbeard, Little St. Simons, Sea and Cumberland, raccoon populations were reduced by trapping and hunting. In addition, cooperators placed 120 cm x 120 cm sections of 5 cm x 10 cm mesh welded-wire fencing over nests to protect from depredations. Cumberland Island Turtle Project personnel used larger screens (183 cm x 183 cm) to discourage raccoons from depredating eggs by tunneling into the nest cavity from the side. Fence sections were secured with steel pencil rod at the corners. On some islands, a combination of standard flat screen and wire cage were used to further deter raccoons. On Sapelo, Ossabaw, Little St. Simons, Little Tybee, and St. Catherines Islands, GADNR used plastic screen (4.1 cm x 4.1 cm mesh) as part of a study to assess the 3

4 effectiveness of an alternative nest shield. Plastic screen was used because of concerns over the high magnetic permeability of metal cages/screens and the possibility of altering the local magnetic field in the area around the nest (Irwin et al. 2004). Feral swine were generally controlled through hunting and trapping (Table 1). Cooperators visually inspected each nest daily for signs of depredation and hatchling emergence. Cooperators recorded all nest depredations and tidal inundation events. Cooperators conducted nest inventories following the emergence of hatchlings. Cooperators excavated nests 5 days after the first emergence. If fire ants were observed in the nest, the nest was excavated immediately. If no hatchling emergence was observed, cooperators excavated nests 70 days after deposition. Cooperators conducted most nest inventories during daylight hours, except on Wassaw, Blackbeard, and Sea Islands, where excavations were conducted at night. During excavations, personnel carefully dug into the nest chamber and removed the contents. If a large number (>10) of live hatchlings were encountered in the upper chamber, cooperators reburied the hatchlings and continued to monitor the nest. If a few live hatchlings were encountered near the bottom of the nest chamber, cooperators counted and released them several meters landward of the high tide line. On selected islands, cooperators recorded the number and orientation of hatchling tracks for each emergence. If hatchlings exhibited a consistent directional movement in a direction other than the sea, cooperators categorized the emergence as a misorientation. If hatchlings moved in an inconsistent or random direction away from the sea, cooperators categorized the emergence as a disorientation. Nest contents were categorized by type including hatched eggs, unhatched eggs, dead hatchlings, and live hatchlings. Cooperators determined the total number of eggs by adding total eggshells (>50% of the shell intact) and the number of unhatched eggs. In the case of relocated nests, the total number of eggs was recorded during the nest relocation process. Following the nest evaluation, project personnel removed the nest contents and buried them behind the primary dunes to ensure they were not confused with active nests. Cooperators entered nest data into an MS Excel spreadsheet and submitted the information to GADNR following the nesting season. We calculated hatching and emergence success using the following formulas: Hatching Success = (Hatched Eggs/Total Eggs)*100. Emergence Success =(Hatched Eggs-(Dead Hatchlings +Live Hatchlings))/Total Eggs*100. We determined nest egg totals by adding the hatched and unhatched eggs found during nest evaluations. If a nest was partially depredated during incubation (raccoons or feral swine), we used the average clutch size calculated from relocated nests as the egg total for hatching and emergence success calculations. 4

5 We used SAS 9.1 (SAS Institute 1990) statistical software to summarize descriptive data and perform statistical analyses. To assess trends in nesting data, we used a log-linear regression with an autoregressive error correction to account for temporal correlation in annual nest totals. We used simple linear regression (MS Excel) to examine the relationship between nest emergence success and nest relocation. We estimated hatchling sex ratios using a technique developed by Godfrey and Mrosovsky (1997) where incubation duration (deposition to first emergence) is used to estimate the proportion of females in a clutch. Although this technique does not have sufficient precision to be used to determine the sex ratio of hatchlings from individual nests, it provides relatively accurate estimates of ratios over a large geographic area. We used a nonparametric ANOVA (Analysis of Variance on ranked emergence success rates) to test the hypothesis that there was no difference in egg hatching and hatchling emergence rates between Islands. We used Duncan s multiple comparison procedure to test for differences between island means. Results and Discussion Status Sea turtle cooperators located a total of 1,649 loggerhead turtle nests on Georgia beaches during 2008 (Table 2). The annual nest total was the highest on record since comprehensive surveys were established in 1989 (Fig. 2). Assuming that 4.5 nests were deposited per female (Scott 2006), we estimated that 366 loggerhead females nested on Georgia beaches in We were not able to detect a significant trend in the 20-year comprehensive nesting dataset using log-linear regression with autocorrelated error model (r 2 = 0.21, n=20, P= 0.55; Fig. 2). Power analysis (Gerrodette 1993) indicated that the minimum detectable rate of change in nesting was 5% annually for the short-term data. To examine long-term nesting trends (>30 years) we used combined nest totals from the 3 islands with long-running nest protection programs including Wassaw, Blackbeard, and Little Cumberland Islands. Results from the regression analysis showed a significant annual decrease of 1.2% in loggerhead nesting (r 2 = 0.18, n=36, P= 0.001; Fig. 3). This long-term decline is similar to declines documented on other Northern Subpopulation beaches (Hopkins- Murphy et al. 2001). It is important to remember, however, that conclusions from long-term nesting data must be viewed with caution. Although nest totals from the 3 islands represent approximately 25% of Georgia s statewide nesting annually, it is possible they are not representative of statewide nesting trends. Overall, the trend information suggests a long-term decline in loggerhead nesting of approximately 1.2% annually. The short-term comprehensive nesting data, however, shows no trend. One interpretation of the results is that the loggerhead nesting population may have stabilized over the last 20 years. An alternative explanation is that a 20-year time-series is not sufficiently long to detect relatively small annual declines in nesting noted in the long time-series 5

6 data. More data (i.e. comprehensive surveys over a longer time series) are necessary to accurately determine the status of loggerhead nesting populations in Georgia. The new Federal recovery plan for the loggerhead sea turtle requires a 2% annual increase in nesting over a generation (50-year period) for loggerheads to be considered recovered in Georgia. Based on current nesting levels, a 2% increase over a generation period would result in a recovery goal of 2,800 nests. With current trend information suggesting a long-term decline, estimating the time to recovery is not possible. However, over the last 20 years, loggerhead nesting populations have averaged less than half the number required to be considered recovered. It is clear that a long-term conservation effort will be necessary to restore loggerhead nesting populations to historic levels. Sea turtle cooperators surveyed a total of 15,073 km of nesting habitat between 15 May and 31 August, This compares with 15,361 km of nesting habitat surveyed in Overall, survey effort has been comparable between years (+ 2%) since we began collecting survey effort data in Loggerhead nesting totals were highest on Cumberland, Blackbeard, and Ossabaw Islands in 2008 (Fig. 4). The coastwide average nesting density was 11.1 nests/km (Table 2; Fig. 5). Nesting densities were variable between islands and ranged from 0.9 nests/km on Tybee Island to 18.4 nests/km on Blackbeard Island (Table 2; Fig. 5). Georgia s overall loggerhead turtle nest density (x=11.1 nests/km) was similar to nesting densities reported from other southeastern beaches within the range of the Northern Subpopulation of loggerhead turtles (D. Griffin, pers. comm., SCDNR; Matthew Godfrey, NCWRC). Nesting success ranged from 40.8% on St. Catherines Island to 78.9% on Wassaw Island (statewide avg.= 58.6%; Table 2). The spatial distribution of nests was similar to previous years, with loggerhead turtles nesting on all surveyed barrier island beaches in Georgia. Nesting was relatively evenly distributed geographically (Fig. 6-18) except along sections of Jekyll, Sea, and St. Simons Islands where beach armoring restricts access to nesting habitat. In past years, nest relocation efforts have resulted in a highly clumped distribution of nests on some beaches. Because the relocation of nests into clumped distributions may result in higher depredation rates on hatchlings (Wyneken and Salmon 1996), beach managers have been asked to avoid the spatial clumping of nests when possible. During 2008, the spatial distribution of nests following nest relocation was similar to the natural distribution of nests (Fig. 6-18). The first loggerhead nest of the 2008 season was deposited on Blackbeard Island on 5 May. The temporal distribution of nesting was similar to past years with most nesting occurring from 20 May through 28 July (Fig. 19). The last recorded nest was deposited on 18 August on Cumberland Island. 6

7 Non-Loggerhead Nesting Records A single green turtle (Chelonia mydas) nest was located in Georgia in A total of 9 green turtle nests were initially reported by cooperators in 2008; however, genetic tests conducted on nest contents indicated that only 1 of the 9 nests were deposited by green turtles (Brian Shamblin, Univ. of Georgia, pers comm.). The remaining 8 nests were loggerhead nests. The green turtle nest was deposited on Cumberland Island on 24 June and had a hatch success of 65%. Green turtle non-nesting emergences were documented on 5 of the 13 survey beaches. Historically, green turtle nesting has been uncommon in Georgia with only 9 nests documented since statewide nest monitoring was established in 1989 (Figure 21). No leatherback nesting activity was documented in Georgia in 2008 (Figure 20). Nest Protection and Management Statewide mean hatching and emergence success were 62.5% and 55.7%, respectively (Table 4). Hatching and emergence success were variable among islands. Analysis of variance on ranked emergence success rates revealed differences in emergence success between islands (F=11.60, df= 11, P=0.0001); however, few individual differences were noted (Table 3). Georgia beaches produced an estimated 100,523 hatchlings during the 2008 nesting season for an average of 655 hatchlings/km (Table 4). The number of hatchlings produced per nest ranged from 28 to 78 hatchlings/nest (Table 4). During 2008, dead hatchlings were present in 35% of nests excavated by cooperators (Table 5). However, few nests (5%) contained a substantial number of dead hatchlings (>25% of production) at excavation. Overall, loggerhead turtle nest incubation duration in Georgia averaged 60.2 days (n=923, SD=4.4). Average incubation durations ranged from 52.5 days on Tybee Island to 63.8 days on Cumberland Island (Table 6). Approximately 40% of loggerhead nests were relocated by cooperators in 2008 to protect them from tidal inundation. Relocation rates were variable among nest protection projects and ranged from 8% on St. Simons Island to 75% on St. Catherines Island (Table 2). No nests were relocated to hatcheries in Beach erosion from tropical storm activity was high in A storm surge associated with tropical storm Fay (8/21-8/24) had a significant impact on hatching success. A total of 111 nests were lost statewide to storm erosion from 8/21-8/24. In addition, approximately 215 nests were inundated for an extended period during high tides associated with this storm. Average hatch success for the inundated nests was below 45%. Statewide, approximately 8.3% of loggerhead nests (n=137) were lost to tidal erosion during 2008 (Table 2). A total of 25.5% (n=421) of nests were tidally inundated at least once during incubation. Nest loss was higher for a randomly selected sample of control nests selected on Sapelo and Ossabaw Islands (n=174). The control nests were left in-situ with no management and were used to assess the effectiveness of nest management 7

8 (nest relocation, predator control). Approximately 24.1 % of the control nests were lost to storm erosion and a total of 36.8 percent (n=64) of nests washed over at least once during incubation. A significant difference was found between hatchling emergence rates by relocation category (Table 7; Non-Parametric ANOVA, F=28.21, df= 2, P<0.0001). Nests that were not washed over averaged 73% emergence success. Nests that were washed over 1-3 times and nests that were washed over more than 3 times averaged 44% and 15%, respectively. We found a significant positive linear relationship (r 2 = 0.05, n=107, P=0.02) between emergence success (calculated excluding depredated nests) and the proportion of nests relocated by island (Fig. 22). Based on the regression relationship, we predict a 44% relocation rate will result in an average emergence success rate of 60%. Interestingly, the complete elimination of nest relocation will result in a nest emergence rate of 54% on average. Statewide loggerhead turtle hatchling sex ratios derived from incubation durations in 2008 indicated a female biased sex ratio (56% female; n=912 nests; 71,216 hatchlings). Female biased sex ratios were produced throughout the nesting season with the exception of early May (Fig. 23). Sex ratios ranged from 43% female on Cumberland Island to 79% female on Tybee Island (Fig. 24). Estimated loggerhead hatchling sex ratios have been variable among years in Georgia. Overall hatchling sex ratios have varied from 49% to 70% female from 1999 to Marcovaldi et al. (1997) reported similar variation in sex ratios in Brazilian loggerheads. The 8-year average sex ratio from Georgia (61% female) is similar to the 6-year estimate of 56.3% female hatchling production reported by Mrosovsky et al. (1984) for nests sampled in South Carolina and Georgia. Currently, the optimal sex ratio for recovery of the northern nesting subpopulation of loggerhead turtles is not known, and it is assumed that the safest course of action is to maintain natural hatchling sex ratios. Complete nest depredations were relatively low in 2008 with a total of 49 nests lost to predators statewide (Table 8). All complete depredations were from feral swine or raccoons. Overall, the proportion of nests partially lost to depredation was approximately 12%. The proportion of partially depredated nests varied among islands and ranged from 2% on Cumberland to 67% on Tybee Island. Raccoons (3%) and ghost crabs (8%) accounted for the largest proportions of partial depredations. However, the partial depredation of a nest by raccoons generally results in the loss of a substantial portion of the clutch; whereas, ghost crabs normally take a few eggs per clutch. Fire ants were documented in very few nests statewide (1%). There was no evidence of nest poaching by humans in Georgia during Nest depredation by feral and native wildlife species can have profound effects on hatchling emergence success. In 2008, island managers spent a considerable amount of time protecting sea turtle nests from depredation. On Ossabaw Island, over 1,600 feral swine were removed through a combination of public hunts, trapping, and hunting by GADNR personnel. Despite these efforts, loggerhead hatching success on Ossabaw was low as a result of feral hog depredations. On Sapelo Island, feral swine were removed during public deer hunts; but because the swine population on Sapelo is generally considered low, 8

9 approximately 25 animals are removed annually (D. Mixon), GADNR, pers. comm.). On Blackbeard, USFWS personnel removed more than 60 feral swine and an untold number of raccoons during the season. Feral swine were also removed during 2 public hunts. On Wassaw Island, feral swine and raccoons were removed opportunistically by USFWS personnel during the course of normal activities. Project personnel on St. Catherines Island were instructed to eliminate any feral swine spotted during the course of regular maintenance activities (G. Bishop pers. comm.). On Cumberland, over 145 feral swine were removed through the combined efforts of National Park Service personnel in 2008 (D. Hoffman, USNPS, pers. comm.). Raccoon depredations were reduced on most islands through a combination of lethal removal and the placement of wire or plastic screen over nests. Ratnaswamy (et. al. 1997) found nest screening to be more effective at reducing raccoon depredations than lethal removal. However, Mroziak et. al. (2000) found wire cages to be generally ineffective in protecting nests in Florida and speculated that predators used wire cages to locate and depredate nests. A combination of predator removal and nest protection appeared to have been effective in reducing raccoon depredations on the Georgia coast. Because raccoons commonly reach through the top of standard flat welded wire screen, a combination of flat screening with a wire cage was the most commonly used screen configuration. On Cumberland Island, park personnel enlarged the size of the standard flat screen from 120 cm x 120 cm to 183 cm x 183 cm to further discourage tunneling by raccoons. Management Recommendations 1. Minimize loggerhead nest depredations by mammalian predators (<5% total nests). Reducing loggerhead nest depredations by feral hogs and raccoons should be accomplished through a combination of nest protection (screen, cage) and predator removal. 2. Minimize nest relocation (maximum of 50%). Nests should be relocated only when nest destruction is certain or the nest is below the spring high tide line. 3. Avoid the relocation of nests into clumped spatial distributions. 4. Ensure survey effort and nesting data is collected and submitted to GADNR in a timely and organized manner 5. Provide training on the identification of green turtle nesting activity. Acknowledgements Managing loggerhead turtles in Georgia is a collaborative effort. Without the dedication and extraordinary effort of project leaders, interns, technicians and volunteers, the management of loggerhead nesting populations in Georgia would 9

10 not be possible. The following is a list of organizations and personnel who contributed significantly to this worthwhile effort in Tybee Island Marine Science Center staff; Maria Procopio, Kristin Bartoo, Tammy and Todd Smith, Cheryl Tilton, and all the Tybee Island Marine Science Center staff and volunteers. Tybee Island Public Works staff; Danny Carpenter and Jimmy Bostwick. Caretta Research Project and Wassaw Island National Wildlife Refuge staff and support personnel; Jane Griess, John Robinette, Kris Williams, Mike Frick, Joseph Pfaller, Peter Range, and all the Caretta Research Project volunteers. GADNR Ossabaw Island staff; Andy Meadows, Eric Esser, Rebecca Perkins, and Lea Scott. St. Catherines Island staff; Royce Hayes, Dr. Gale Bishop, Dr. Terry Norton, Katherine McCurdy, R. Kelly Vance, Fred Rich and all the St. Catherine s Island Sea Turtle Research and Conservation Program student volunteers. Blackbeard National Wildlife Refuge and support personnel; Debra Barnard- Keinath, Jane Griess, Ian Paige, Julia Keating, Tiffany Klein, Cassie Whaley, Scott Gilje, Shaw Davis. GADNR personnel on Sapelo Island; Emily Abernethy, Fred Hay, and Dorsett Hurley. Little St. Simons staff Scott Coleman, Sydney Sheedy, and Abby Sterling. Sea Island staff; Stacia Hendricks, Gwyneth Moody, Jeannie Miller, Jan Mackinnon, Georgia Graves, and Casey Mclean. St. Simons Island; Virginia and Don Herrman, Gloria and William Ramseur, and all of the St. Simons Island Sea Turtle Project volunteers. Jekyll Island staff and support personnel; Dr. Terry Norton, Stephanie Ouellette,and all the Georgia Sea Turtle Center staff and volunteers. Little Cumberland Island staff and support personnel; Rebecca Bell, Jacob Sobin, Ben Morrison and Claude Vaughn. Cumberland Island staff; John Fry, Doug Hoffman, Casey Agueri, and Kristin Williams. Georgia DNR Staff; Brad Winn, Clay George,and Kate Sparks provided technical assistance coastwide. David Mixon, Wildlife Resources Coastal Area Supervisor, provided housing for technicians on Sapelo and Ossabaw Islands. Literature Cited Gerrodette, T Program TRENDS. organizations/courses/97wlf625/guide.htm Godfrey, M.H. and N. Mrosovsky Estimating the time between hatching of sea turtles and their emergence from the nest. Chelonian Conservation and Biology 2(4): Hopkins-Murphy, S. R., T. M. Murphy, C. P. Hope, J. W. Coker, and M. E. Hoyle Population trends and nesting distribution of the loggerhead turtle (Caretta caretta) in South Carolina Final Report to the USFWS. South Carolina Dept. Nat. Res. 41 pp. Irwin, W. P., A. J. Horner, L. J. and K. L. Lohmann Magnetic field 10

11 distortions produced by protective cages around sea turtle nests: unintended consequences for orientation and navigation? Biological Conservation 118 (2004) Marcovaldi, M. A., M. H. Godfrey, N. Mrosovsky Estimating sex ratios of loggerhead turtles in Brazil from pivotal incubation durations. Can. J. Zool. 75: Mrosovsky, N., Hopkins-Murphy, S. R., and J. I. Richardson Sex ratio of sea turtles: seasonal changes. Science 225: Mroziak, M. L., M. Salmon, K. Rusenko Do wire cages protect sea turtles from foot traffic and mammalian predators? Chelonian Conservation and Biology. 3(4): Murphy, T. M., and S. R. Hopkins Aerial and ground surveys of marine turtle nesting beaches in the southeast region, United States. Final report to National Marine Fisheries Service (Contract NA83-GA-C-00021). 73 pp. National Marine Fisheries Service and the U. S. Fish and Wildlife Service Recovery plan for the Northwest Atlantic Population of the Loggerhead Sea Turtle. National Fisheries Service, Silver Spring, MD. SAS/STAT Users Guide, Version 8.2, SAS, Research Triangle Park, Cary, NC. Scott, Jason Use of satellite telemetry to determine the ecology and management o loggerhead turtle (Caretta caretta) during the nesting season in Georgia. MS thesis. University of Georgia. 162 pp. Wyneken, J. and M. Salmon Aquatic predation, fish densities, and potential threats to sea turtle hatchlings from open-beach hatcheries: final report. Technical Report submitted to Broward County Board of Comm., Dept. of Nat. Res. Prot., Bio. Res. Division. 47 pp. 11

12 Table 1. Barrier island ownership and nest protection strategies utilized by loggerhead turtle projects in Georgia, Survey Method Nest Protection Island Ownership Nest protection project Standard daily survey (dawn) Night survey- (Saturation tagging ) Flat screen (welded wire) Cage (welded wire) Flat screen (Plastic) Supp. screen Cage (hardware (Plastic) cloth) Live- trap raccoons Live- trap feral hogs Trap/ remove ghost crabs Removal predatorsfirearms Tybee Island Private Tybee Marine Science Center X Little Tybee/ Myrtle Island Little Tybee/ Williamson Island GADNR GADNR Little Tybee Sea Turtle Project X X X None Wassaw Island USFWS Caretta Research Project X X X X Pine Island USFWS None Ossabaw Island GADNR GADNR Staff X X X X X St. Catherine's Is. Private St. Catherines Is. Sea Turtle Res. and Conserv. Prog. X X X X X X Blackbeard Island USFWS USFWS, Savannah Coastal Refuges X X X X X X Sapelo Island GADNR GADNR Staff Wolf Island USFWS None Little St. Simon's Is. Private Little St. Simon's Is. Resort Staff & GADNR Staff Sea Island Private Sea Island Co. Staff St. Simon's Island Private St. Simons Island Sea Turtle Project X Jekyll Island State of Georgia X X X X X X X X X X Jekyll Island Authority Staff X X X Little Cumberland Is. Private Cumberland Island USNPS LCI Homeowners Assoc. X X X X X X X Cumberland Island National Seashore Staff X X X X X X X 12

13 Table 2. Summary of loggerhead turtle nesting statistics in Georgia, Beach Length Island (km) Tybee Island 7.0 Little Tybee/Myrtle Island 1.9 No. of nests Nesting density (Nests/km) Non-nesting emergencesabove high tide (NEA) Nesting success (Nests/ (nests+ NEA)) Nests left insitu Nests relocated % of total nests relocated Nests subjected to tidal washover % washed over Nests lost to storm events (erosion) Wassaw Island Ossabaw Island St. Catherines Island Blackbeard Island Sapelo Island Little St. Simons Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island Cumberland Island Statewide Totals , , % nests lost to storm events 13

14 Table 3. Estimated loggerhead turtle nest hatching and emergence success in Georgia, Significant differences in mean hatching (F=10.99, df=11, P=0.0001) and emergence success (F=11.60, df=11, P=0.0001) were found between islands using a nonparametric analysis of variance. Duncan's multiple comparison procedure was used to test for differences between means. Hatching and emergence success were calculated using all nests including partially depredated nests and nests lost to storm erosion. Hatching success 1 Emergence success 1 Island N Mean SD Island N Mean SD Blackbeard Island A Blackbeard Island A Wassaw Island A Tybee Island A B St. Catherines Island A Wassaw Island A B Tybee Island A Cumberland Island A B Cumberland Island A B Sapelo Island A B C Jekyll Island A B C St. Catherines Island A B C Sapelo Island A B C Little St. Simons Island A B C Little St. Simons Island A B C Jekyll Island A B C Sea Island A B C Sea Island B C Ossabaw Island B C Ossabaw Island B C Little Tybee/Myrtle Island C Little Tybee/Myrtle Island C Little Cumberland Island C Little Cumberland Island C St. Simons Island 0.. St. Simons Island 0.. Total 1, Total 1, Means with the same letter are not significantly different. 14

15 Table 4. Loggerhead turtle hatchling production in Georgia, No. of sampled nests Total hatchlings produced Hatchlings/km Hatchlings/nest Length of Island beach (km) Tybee Island Little Tybee/Myrtle Island Wassaw Island , Ossabaw Island , St. Catherines Island , Blackbeard Island ,683 1, Sapelo Island , Little St. Simons Island , Sea Island , St. Simons Island Jekyll Island , Little Cumberland Island , Cumberland Island , Total , ,

16 Table 5. Summary of dead loggerhead turtle hatchlings found during nest inventories in Georgia, Island n No. of nests with at least 1 dead hatchling at excavation % No. of nests with >25% of hatchlings dead at excavation % Tybee Island Little Tybee/Myrtle Island Wassaw Island Ossabaw Island St. Catherines Island Blackbeard Island Sapelo Island Little St. Simons Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island Cumberland Island Total 1,

17 Table 6. Loggerhead turtle nest incubation durations (deposition to first hatching) in Georgia, Incubation Duration Island N Mean-nests relocated to dunes SD N Meanin-situ nests SD N Overall mean SD Tybee Island Little Tybee/Myrtle Island Wassaw Island Ossabaw Island St. Catherines Island Blackbeard Island Sapelo Island Little St. Simons Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island Cumberland Island Total

18 Table 7. Loggerhead hatchling emergence success by tidal inundation category in Georgia, Emergence success is calculated excluding depredated and relocated nests. Emergence Success Island N Not Washed over SD N Washover (1-3 times) SD N Washover (>3 times) SD Tybee Island Little Tybee/Myrtle Island Wassaw Island Ossabaw Island St. Catherines Is Blackbeard Island Sapelo Island Little St. Simons Is Sea Island St. Simons Island Jekyll Island Little Cumberland Is Cumberland Island Total

19 Table 8. Summary of loggerhead turtle nest depredations (complete depredations only) in Georgia, Nests depredated by feral swine (complete loss) %.. Nests depredated by raccoons (complete loss) %.. Total nests depredated (complete loss) %.. No. Island nests Tybee Island 6 Little Tybee/Myrtle Island Wassaw Island Ossabaw Island St. Catherines Island Blackbeard Island Sapelo Island Little St. Simons Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island Cumberland Island Total 1,

20 Tybee Island Little Tybee / Myrtle Island Little Tybee / Williamson Island Wassaw Island Pine Island Ossabaw Island St. Catherine's Island Blackbeard Island Sapelo Island Wolf Island Little St. Simon's Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island W N E Cumberland Island S Kilometers Figure 1. Georgia barrier islands,

21 Loggerhead Nests 1,800 1,600 1,400 1,200 1, Figure 2. Loggerhead turtle nest totals from standardized daily surveys beaches in Georgia, Daily surveys were not conducted on Little Tybee/Williamson, Pine and Wolf Islands. No trend was detected using loglinear regression with an autoregressive error correction (r 2 = 0.21, n=20, P= 0.55). 21

22 Loggerhead Nests Figure 3. Combined loggerhead turtle nest counts from 3 Georgia beaches (Wassaw, Blackbeard, Little Cumberland), (N=36). Log-linear regression with autoregressive error correction showed a significant declining trend of 1.2% annually (r 2 = 0.18, n=35, P= 0.01). 22

23 Loggerhhead Nests NA NA NA Tybee Island Little Tybee/Myrtle Island Little Tybee/Williamson Island Wassaw Island Pine Island Ossabaw Island St. Catherines Island Blackbeard Island Sapelo Island Wolf Island Little St. Simons Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island Cumberland Island 23 Figure 4. Loggerhead turtle nest totals in Georgia by island, Daily surveys were not conducted on Little Tybee/Williamson, Pine, and Wolf Islands.

24 Figure 5. Loggerhead turtle nesting density in Georgia, Daily surveys were not conducted on Little Tybee/Williamson, Pine, and Wolf Islands Cumberland Island Loggerhead Nests/km Tybee Island Little Tybee/Myrtle Island Little Tybee/Williamson Island Wassaw Island Pine Island Ossabaw Island St. Catherines Island Blackbeard Island Sapelo Island Wolf Island Little St. Simons Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island NA NA NA 24

25 N W E S Kilometers Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 6. Spatial distribution of loggerhead turtle nests on Tybee Island, Georgia,

26 N W E S Kilometers Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 7. Spatial distribution of loggerhead turtle nests on Little Tybee/Myrtle Island, Georgia,

27 N W E Legend Relocated In-situ S Kilometers Distribution prior to nest relocation Distribution following nest relocation Figure 8. Spatial distribution of loggerhead turtle nests on Wassaw Island, Georgia,

28 N W E S Legend Relocated In-situ Kilometers Distribution prior to nest relocation Distribution following nest relocation Figure 9. Spatial distribution of loggerhead turtle nests on Ossabaw Island, Georgia,

29 N W E S Kilometers Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 10. Spatial distribution of loggerhead turtle nests on St. Catherines Island, Georgia,

30 Distribution prior to nest relocation Distribution following nest relocation Relocated In-situ Legend N E W S Kilometers Figure 11. Spatial distribution of loggerhead turtle nests on Blackbeard Island, Georgia,

31 Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 12. Spatial distribution of loggerhead turtle nests on Sapelo Island, Georgia,

32 N W E S Kilometers Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 13. Spatial distribution of loggerhead turtle nests on Little St. Simons Island, Georgia,

33 W N S E Legend Relocated In-situ Kilometers Distribution prior to nest relocation Distribution following nest relocation Figure 14. Spatial distribution of loggerhead turtle nests on Sea Island, Georgia,

34 N W E S Kilometers Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 15. Spatial distribution of loggerhead turtle nests on St. Simons Island, Georgia,

35 N W E S Kilometers Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 16. Spatial distribution of loggerhead turtle nests on Jekyll Island, Georgia,

36 N W E S Kilometers Legend Relocated In-situ Distribution prior to nest relocation Distribution following nest relocation Figure 17. Spatial distribution of loggerhead turtle nests on Little Cumberland Island, Georgia,

37 Distribution prior to nest relocation Distribution following nest relocation N E W S Kilometers Figure 18. Spatial distribution of loggerhead turtle nests on Cumberland Island, Georgia,

38 /22-4/28 4/29-5/5 5/6-5/12 5/13-5/19 5/20-5/26 5/27-6/2 6/3-6/9 6/10-6/16 6/17-6/23 6/24-6/30 7/1-7/7 7/8-7/14 7/15-7/21 7/22-7/28 No. of loggerhead nests 7/29-8/4 8/5-8/11 8/12-8/18 8/19-8/25 8/26-9/1 38 Figure 19. Temporal distribution of loggerhead turtle nesting in Georgia, 2008 (n=1,635).

39 Leatherback Turtle Nests Figure 20. Leatherback turtle nesting in Georgia,

40 Green Turtle Nests Figure 21. Green turtle nesting in Georgia,

41 90 80 Hatchling emergence success (%) % Loggerhead nests relocated Figure 22. Relationship between the proportion of loggerhead nests relocated and nest emergence success on Georgia's barrier islands, Emergence success was calculated excluding depredated nests. Linear regression analysis showed a significant positive relationship between the % of loggerhead turtle nests relocated and hatchling emergence success (r 2 = 0.05, n=107, P= 0.02). 41

42 % total hatchlings May-15 May 16 May-31May 1 Jun-15 Jun 16 Jun-30 Jun 1 Jul-15 Jul 16 Jul-31 Jul 1 Aug-15 Aug 16 Aug-31 Aug Female Male Figure 23. Estimated seasonal loggerhead turtle sex ratios in Georgia, 2008 (n = 912 nests; 71,216 hatchlings). Sex ratios estimated from Godfrey and Mrosovsky

43 Figure 24. Estimated loggerhead turtle sex ratios for Georgia barrier islands, 2008 (n=912 nests; 71,216 hatchlings). Sex Ratios estimated from Godfrey and Mrosovsky Females Males Tybee Island Little Tybee Wassaw Island Ossabaw Island St. Catherines Island Blackbeard Island Sapelo Island Little St. Simons Island Sea Island St. Simons Island Jekyll Island Little Cumberland Island Cumberland Island % of total hatchlings 43