A twenty year mark-recapture dataset from the loggerhead nesting beach on Keewaydin Island, off the southwest coast of Florida, was analyzed using a two-state open robust design model in Program MARK to provide insight into recent nesting declines in the state. A total of 2,292 encounters representing 841 individual tag IDs were used for this analysis. Survival was estimated at 0.73 (95% CI 0.69-0.76), and there was no evidence from remigration rate or clutch frequency to suggest the composition of the nesting assemblage had changed over time. The mark-recapture analysis was supplemented with a satellite tracking component to identify the offshore foraging areas utilized by Keewaydin nesters. Eleven nesting females were outfitted with platform terminal transmitters, which transmitted for 42 to 300+ days including inter-nesting intervals and subsequent migration to foraging grounds. Site fidelity tests and kernel density home range analyses were used to describe foraging habitats. Females foraging in the eastern Gulf of Mexico were within the recent 64 m bottom longline fishery restriction. Areas identified as important habitats during the remigration interval should be used to inform managers in creating targeted management strategies to aid population recovery without the use of broad fishery closures.

Vocalization behavior of captive loggerhead shrikes was studied at the Avian Science and Conservation Centre of McGill University. In the first stage, calls of two pairs kept in indoor cages were individually recorded not only to catalogue these calls spectrographically and quantitatively but also to use them in identifying the birds sexually. Males vocalized 21 call figures for 16.50% of the observation time and females, 8 call figures for 2.64% of the observation time. Males contiguously delivered 1 to 11 bouts with a mean of 7.25 min for a rate of 6.06 bouts/h; females delivered 1 to 9 bouts with a mean of 4.07 min for a rate of 1.27 bouts/h. Males not only vocalized at a higher rate and longer than females, but also demonstrated trill calls which the females did not do. In the second stage, five pairs were paired in large outdoor breeding pens. Their calls were recorded and current visual displays observed in an effort to understand calls related to breeding behaviors. Two new calls figures vocalized by males as well as 2 call figures by young shrikes were recorded. Each male demonstrated distinctive calls that differed from those of other males during nest-site selection, nest building and copulation, but similar calls during food offering, aggressive and alarm behavior. Despite the call differences, all males performed similar visual displays during the above activities. Conversely, breeding females gave no calls, other than harsh calls during food offering, food begging, aggressive and alarm behaviors.

The loggerhead sea turtle Caretta caretta is listed as threatened with extinction on the US Endangered Species Act. Those loggerhead turtles that nest on US beaches from North Carolina to north-east Florida are a genetically distinct subpopulation. This subpopulation is small, and may be declining. To obtain information about the migratory pathways of these turtles we tracked post-nesting movements of five females by satellite from their nesting beach at Wassaw Island, Georgia. Four turtles migrated north of the nesting beach, of which three moved to coastal waters of mid Atlantic states (total distances of 157-1,458 km). Efforts to reduce mortality of northern subpopulations of loggerhead turtles need to focus on identifying and reducing threats in north-east US waters.

No description available.

Beach nourishment has become common in Florida and it occurs on beaches that are major loggerhead (Caretta caretta) nesting grounds. Despite efforts to use beach-quality sand, nourishment sand may be different in grain size, moisture content, shear resistance and temperature when compared to native sand. Two main aspects of loggerhead nesting may be affected by nourishment. First, nourishment may reduce nesting success [(female nesting emergences/ female total emergences) X 100] due to physical barriers (i.e., scarps or steep cliffs) that can impede gravid females. Second, nourishment may reduce reproductive success {i.e., hatching success) by altering the nestsand environment. The objective of this study was to compare loggerhead nesting success, nest placement, slopes at nest sites, nest depths, incubation periods, reproductive success and egg fates among an old renourished beach {"south"), a recently nourished beach ("treatment") and a natural beach ("control") at Sebastian Inlet, Florida in 1996, 1997 and 1998. In all three years, nesting success was significantly different among study sites. After nourishment (1997), nesting success was reduced at the treatment site due to a seaward scarp. A year later (1998), the scarp was leveled and nesting success improved. Nest placement was not significantly different between study sites prior to nourishm_ent of the treatment study site (1996), but it was after nourishment (1997) and one-year post-nourishment (1998). After nourishment, most nests at the treatment beach were placed too close to the water or too close to the dune. There were no significant differences in the slope at nest sites in 1997; suggesting females may have selected similar increases in slope, but at varied cross-shore locations. Nest depths were significantly shallower at the treatment beach after nourishment, probably due to higher compaction of the nourishment sand. In addition, incubation periods were significantly longer on the nourished beaches one year post-nourishment. Loggerhead hatching success was significantly reduced on the nourished beaches in 1996 and 1997. The reduction was seen primarily in a larger proportion of eggs that were arrested early in development. The higher moisture in the nourishment sand may have impeded gas exchange, which resulted in decreased hatching success. One year post-nourishment (1998), there were no significant differences in hatching success. The lack of rainfall in 1998 may have introduced better incubation conditions on the nourished beaches. Researchers at the Florida Institute of Technology continued to show that the nourishment sand exhibited significantly smaller grain size, higher moisture content, lower temperature and higher shear resistance. These attributes were probably responsible for many of the results reported herein. However, other variables such as non-random nest depredation, inlet influences and water table levels may have also contributed to the results.

Loggerhead sea turtles nest on either the Atlantic or Gulf coast of Florida. The hatchlings from these nests migrate offshore in opposite directions. The purpose of my study was to determine if Gulf coast hatchlings use magnetic maps, as Atlantic coast hatchlings do, both to locate areas favorable for survival in the Gulf of Mexico and to orient appropriately within surface currents that could transport them into the Atlantic Ocean. To find out, I presented Gulf coast hatchlings with magnetic fields corresponding to different locations inside the Gulf, and within currents leading into (Florida Straits) and within (Gulf Stream) the western portion of the Atlantic Ocean. I conclude that Gulf coast hatchlings (i) use a high resolution magnetic map for navigation within the Gulf of Mexico, (ii) initially remain within the eastern Gulf, but later may (iii) gain entry into currents that transport them into Atlantic waters. / by Maria W. Merrill. / Thesis (M.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

South Florida's loggerhead (Caretta caretta), green (Chelonia mydas) and leatherback (Dermochelys coriacea) sea turtles hatchling have environmentally determined sex. The in situ nest mean hatchling sex ratios (SR) were highly female-biased : loggerhead F=0.89) and green turtle F=0.81; leatherback's SR was nearly balanced (0.55F). Nest temperatures and SRs differed between leatherbacks and loggerhead and green turtles. The latter two did not differ. The loggerhead response parameters were estimated within biological limitations by both 50-65% of incubation and mean middle 1/3 temperature. The maximum middle 1/3 temperature was the best-fit predictor for green turtles. No best-fit sex ratio-temperature response could be identified for leatherbacks. Clutches incubating under natural conditions can vary greatly in SR ; TRT differences may account for differences among species' sex ratios. / by Micah Marie Rogers. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

With the different threats sea turtles are currently facing, such as habitat reduction and pollution, increase of fishing and harvesting of aquatic resources by Humans, or invasive species, it is important to learn as much as possible about their biology and behaviour in order to ensure the success of conservation programs. In this study, loggerhead sea turtles (Caretta caretta) feeding behaviour duration as well as energy expenditure approximation during a feeding event were tested and compared using two different types of food: green shore crabs (Carcinus maenas) or Japanese clam (Ruditapes phillipinarum) or Venus clams (Chamelea gallina). The data show that the turtles took longer to approach the crabs but took more time to eat the clams. However, comparison of energy expenditure values for the feeding phase showed no significant differences. The turtles were observed to eat the clams’ shell as well as their meat. These shells are rich in calcium, which is one possible explanation for this behaviour. This study shows that data loggers represent a viable tool for studying the behaviours of marine animals.

Climate change has the potential to expose sea turtle nests to higher temperatures, which may negatively impact sea turtle hatchling vigor. In this study, loggerhead and green hatchlings were sampled from the Boca Raton, Florida beach and via lab incubation, and hatchling vigor was determined. Elevated nest temperatures decreased loggerhead and green turtle hatchling performance and corticosterone levels, with the most significant effects found in hatchlings exposed to maximum incubation temperatures above 35°C during late development. Lab-incubated loggerhead post-hatchling corticosterone levels and growth rates were also determined. The differences seen in corticosterone levels with overall nest incubation temperatures, mean temperatures during early, middle or late stages of development, and its negative correlation with hatchling performance improves our understanding of the underlying physiological mechanisms linking elevated incubation temperatures and sub-lethal physiological effects that may significantly impact hatchling survival, a critical step for sea turtle conservation in south Florida and elsewhere. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Florida’s sea turtle populations are increasing due to conservation efforts; however, sea turtle species are vulnerable to climate change. Turtles exhibit temperaturedependent sex determination, in which nest environment influences sex. Environmental changes may produce altered sex ratios that limit reproduction potential; therefore hatchling sex ratios should be monitored. Hatchlings are not externally sexually dimorphic, making sex identification difficult. This study established baseline plasma hormone concentrations in hatchling and post-hatchling green (Chelonia mydas) and loggerhead (Caretta caretta) sea turtles using High Performance Liquid Chromatography. Five hormones were assayed and were present in the majority of samples (testosterone: N.D.-10.12, progesterone: N.D.-0.43, estradiol: N.D.-4.78, estriol: N.D.-5.55 and estrone: N.D.-1.67 μg/mL). Plasma hormones did not distinguish hatchling sex because male and female ranges overlapped. Hormone concentrations varied with sex but also with incubation temperature, indicating that climate change could impact hatchling and posthatchling hormone profiles and thus could impact future fitness. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection