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Gopher tortoises (Gopherus polyphemus) occur in a variety of habitats, but are primarily associated with sandhill communities. In peninsular Florida, however, mesic flatwoods make up the largest area of habitat, and scrub often replaces sandhill on inland ridges. Tortoise ecology is poorly understood in these habitats and few data are available to guide management. We surveyed tortoise burrows and assessed vegetation in scrub, flatwoods, and pine plantations on flatwoods soils at Avon Park Air Force Range in south-central Florida. Densities of noncollapsed burrows in scrub (1.93/ha) and flatwoods/plantations (1.42/ha) were generally lower than is typical for sandhill (3.25–9.95/ha), although total abundance was high (>20,000) because of the large habitat area. In scrub, low burrow densities may be due to low abundance of food plants. Nonetheless, the burrow density in scrub was significantly higher than in flatwoods/plantations, where food was abundant but soils were poorly drained and burrows were often flooded. The percentage of collapsed burrows was significantly higher in scrub (53%) than in flatwoods/plantations (35%), although a higher percentage of the remaining (noncollapsed) burrows were active in scrub (23%) than in flatwoods/plantations (16%). These patterns (and data from a subsequent radiotelemetry study) suggest that tortoises in scrub maintain strong fidelity to individual burrows, and frequently abandon others, whereas tortoises in flatwoods share burrows and move among them regularly, but rarely abandon them. This sharing and continual reuse of available burrows suggests a possible limitation on suitable conditions for burrow construction in flatwoods, probably related to the high water table. We suggest that scrub and flatwoods may constitute suboptimal habitats for gopher tortoises, due to low abundance of food in scrub and poorly drained soils in flatwoods. Nonetheless, large numbers of tortoises may occupy scrub and flatwoods, necessitating better understanding of their ecology in these habitats.
Maximilian's snake-necked turtle, Hydromedusa maximiliani, is an endemic and vulnerable long-lived freshwater turtle from eastern Atlantic mountainous rainforest regions of Brazil. Three scenarios (real population, optimistic population, and pessimistic population) based on the species' life-history data and carrying capacity estimates collected throughout 13 yrs were generated with VORTEX and subjected to sensitivity tests to verify the influence of demographic (mortality rate and inbreeding depression) and environmental (fire and deforestation catastrophes) parameters on population viability. The results showed significant differences among the viability scenarios, with extinction probability ranging from 6% to 99%. These analyses illustrate that environmental and demographic stochasticity can negatively impact populations of H. maximiliani and emphasize the necessity of protecting areas for long-lived organisms inhabiting regions impacted by humans.
Seasonal and temporal-spatial distributions of green turtle (Chelonia mydas) nesting activity were assessed at Aldabra Atoll Seychelles, the second largest green turtle rookery in the Western Indian Ocean (WIO), based on morning counts of fresh turtle tracks conducted during 1980–2011. The datasets used in the analyses are derived from an average of 3–4 surveys per month at two index sites representing ∼30%–42% of total annual nesting during 1980–1989 and ∼58% during 1995–2011; and monthly surveys conducted at another two remote sites, which accounted for an additional 20% of annual nesting (total ∼78%) during 2002–2011. Turtles engaged in year-round nesting during the season defined as December to November and characterized by patterns of high intra- and interannual variation. In some seasons, nesting peaked primarily during February to May, and in others during May to September, but on average during 1995–2011, a clear unimodal pattern emerged with nesting activity greatest during February to September, peaking during April to June, and lowest in November–December. The two Primary Index Sites situated 2.2 km apart on the west coast and separated by a lagoon entrance had mean peak nesting dates that consistently differed by more than a month. Possible explanations for the differences are discussed. At Aldabra, the timing of the 1997–1998 ENSO event coincided with a disruption in normal nesting cycles during 1998 through 2002 and the highest levels of nesting recorded at Aldabra to date during the 2000–2001 season. Comparison of seasonal median peak nesting dates at five green turtle rookeries in the WIO suggests an inverse relationship with latitude among four of them, with those in the lower latitudes peaking during the austral autumn and winter and in the higher latitudes during the austral summer, an indication that temperature may be moderating nesting seasonality in the WIO.
The Sonoyta mud turtle (Kinosternon sonoriense longifemorale) is a member of the unique desert riparian fauna isolated along the Rio Sonoyta watershed in northern Sonora, Mexico, and southern Arizona. This subspecies occupies six sites along the Rio Sonoyta, a pool at Quitovac in Sonora, and one pond at Quitobaquito Springs in Organ Pipe Cactus National Monument in Arizona. Since the mid-1980s, population estimates for the US population have ranged from 39–153 individuals. In 2006–2007, the human-made Quitobaquito Pond began losing water, and discussions were held concerning the fate of the turtles. During three salvage efforts all Sonoyta mud turtles encountered were captured and transported to temporary holding facilities. Because the minimum number of turtles needed for re-establishment was unknown, we conducted a Population Viability Analysis (PVA) to determine the number of Sonoyta mud turtles that should be held in an assurance colony. Results from both our PVA and previous work suggested that juvenile survivorship has the strongest effect on female transition rates from nonreproductive to reproductive age classes and in turn population growth; thus, a wide range of age classes should be maintained in an assurance colony.
Marine turtles in the Gulf of Mexico are at risk due to many anthropogenic threats including habitat degradation, commercial fishing, and petroleum activities. The severity of this risk was made apparent in 2010 with the occurrence of the Deepwater Horizon oil spill. The objectives of this study were to assess long-term trends in abundance and reproductive parameters for this genetically distinct nesting group. From 1994 to 2010, morning surveys were conducted along 3 beaches on the St Joseph Peninsula, Florida, including within our primary study site on Cape San Blas. Nest abundance on all 3 beaches declined by at least 47% (p < 0.01). Mean nesting success on Cape San Blas was 40% and also declined (p = 0.002). Mean clutch size was 108 and mean emergence success was 58%. Throughout the study there were no changes in clutch size and emergence success. We found that nesting characteristics for the northern Gulf of Mexico subpopulation appear similar to those from other loggerhead turtle nesting groups in the southeastern United States in some ways, such as emergence success, timing of peak nesting, and incubation duration and different in other ways such as nesting success. Variation in some of the parameters may indicate turtles among the different nesting groups experience different environmental conditions. The severity of declines in nest abundance and the low nesting success reported for this small subpopulation suggest potentially serious consequences for this nesting group.
Incidental observations on nest predation dynamics at 2 map turtle (Graptemys spp.) nesting sites along the Wisconsin River, Iowa County, Wisconsin, were obtained during primary research on the use of electric fencing to decrease turtle nest predation. Sites were continuously monitored by digital trail cameras during the 2008–2011 reproductive seasons. Raccoons (Procyon lotor) displayed temporally focused turtle nest foraging efforts across both sites and years and were the only confirmed nest predators. Striped skunks (Mephitis mephitis), Virginia opossums (Didelphis virginiana), coyotes (Canis latrans), and American crows (Corvus brachyrhynchos) were less frequent on site but also displayed recurring seasonal chronologies. Nest predation levels exceeded 90%, with short nest survival timelines suggesting relatively high predation pressures on these sites. Available data provided only limited evidence that post–nest construction rainfall reduced nest predation rates.
Incidental observations on the nesting ecology of Ouachita map turtles (Graptemys ouachitensis) were made at 2 sites on the Wisconsin River, Iowa County, Wisconsin, during research on the use of electric fencing to decrease turtle nest predation. Sites were continuously monitored by digital trail cameras during the 2008–2011 reproductive seasons. Turtles nested in a bimodal diel pattern overall, the result of a reduction of midday nesting activity on relatively warm days. Nesting duration was relatively short compared to most emydids and was inversely correlated with ambient air temperatures. Precipitation within 24 hrs prior to nesting was not associated with levels of nesting activity. Younger nests appeared to have greater survival during short-term flooding events than did older nests.
The loggerhead turtle (Caretta caretta) is listed as an endangered species in the International Union for Conservation of Nature Red List, and this is critical for the maintenance of future genetic diversity. For the conservation of this species, it is important to understand the relationships between sexual selection and gene flow in the evolution of biodiversity. It is, however, virtually impossible to study sexual selection in such an oceanic species in the field. We investigated the relationships between mate preference and genetic relatedness of reproductively active loggerhead turtles (n = 7) kept in a tank at an aquarium using 4 different estimators of pairwise genetic relatedness (r) based on the genotypes at 23 microsatellite loci. Although relationships between total number of courtship behavior and r were not significant in the 4 estimators, there were significant and consistent inverse relationships between cumulative duration of mountings and r in all of the estimators. In addition, significant or marginally significant relationships were found between mean r for each female and number of sires in her successive clutches in 3 of the 4 estimators. However, we found no evidence that more distantly related pairs produced more offspring than the assumption of random mating except for 1 estimator or any relationship between r of parents and their reproductive success (hatchability). Based on these results, the most parsimonious explanation is that loggerhead turtles in the tank tend to prefer their mate(s) according to genetic relatedness but that the extent of female mate selection and the relationship between mate selection and fitness still remain debatable.
The radiated tortoise (Astrochelys radiata) is facing a significant risk of extinction within the next few decades as a direct result of poaching due to the increasing popularity of the species as bush meat. Sampling across the species range revealed a mean carcass encounter rate of 2.2/km of transect, with highest levels of poaching within the Linta and Menarandra river regions. No poaching was recorded within the 2 protected areas within the core of the species range. Improved local law enforcement, in addition to community-based conservation initiatives, is critical to combating this crisis.
Road mortality of South African tortoises has not been evaluated. I recorded the number and distribution of remains of Homopus femoralis directly along 8.4 km of tar road with low traffic volume in the Karoo, South Africa. I identified 48 carcasses, with a relatively high number found along 1.5 km of road. Multiple dry culverts already present under this stretch of road provide an opportunity to reduce mortality by adding structures to guide tortoises to the underpasses.
We investigated nest-site characteristics and clutch success of hawksbill sea turtles (Eretmochelys imbricata) nesting on Shidvar Island, Hormozgan Province, in the Islamic Republic of Iran. We found that hawksbills tended to cluster their nests at a specific elevation above sea level, and that emergence success was highest in nests nearest to this preferred elevation, declining at higher and lower elevations. These results suggest that elevation might be an important cue for nest-site selection in this population.
We studied plastron-shaped asymmetry of the Eurasian Spur-Thighed Tortoise, Testudo graeca ibera, as related to life stage, gender, and distribution. Our analyses of 523 individuals showed that fluctuating asymmetry (FA) in plastron shape varied with gender (males exhibited higher levels of FA than did females) and across populations, whereas life stage had no significant effect. Although we could not identify the potential sources of variation responsible for the observed patterns of developmental instability, our study shows the value of FA as a method for studies of developmental instability in turtles.
Information on sea turtle population trends is fundamental to assess the population status and the effects of conservation measures, and is considered a priority for sea turtle conservation. To provide insights on trends at sea, we compared by-catch data from long-liners fishing in the Gulf of Taranto in 2 periods: 1978–1979 and 1998–2003. A total of 653 loggerhead sea turtles (Caretta caretta) were captured in 2679 fishing sets targeting swordfish and albacore tuna; catch rates were significantly higher in the second period, while average turtle size was smaller. Although possible effects of sampling techniques cannot be excluded, a negative trend in the number of turtles in the study area and period was unlikely.
We tracked two adult female green turtles (Chelonia mydas) from their nesting location on Masirah Island, Oman (lat 20.441°N, long 58.843°E) into the Red Sea. Comparing these tracks with published movements of nesting loggerhead (Caretta caretta) and olive ridley (Lepidochelys olivacea) turtles, also tracked from Masirah, revealed remarkably different inter-specific patterns of post-nesting dispersal. High-capacity artisanal fisheries, with undescribed levels of sea turtle bycatch, exist within the region, making introduction of effective conservation measures difficult.
Loggerhead turtle (Caretta caretta) nesting in the Southwest Atlantic has been monitored for decades, but information from northern Rio de Janeiro State (Brazil) has been lacking until now. In this study, we documented 11,086 nests laid between the 1992/1993 and 2010/2011 nesting seasons (∼1000 nests per season) and found significant variations in incubation period and hatching success among in situ and relocated nests. Because loggerhead nests in Rio de Janeiro are presumed to produce a large proportion of male hatchlings because of lower average incubation temperatures, this area is an important component of loggerhead population biology and conservation in Brazil and the southwest Atlantic region.
Low concentrations of several pesticides including organochlorines and polychlorinated biphenyls were found in the blood and eggs of nesting female flatback turtles, Natator depressus, collected from Curtis Island in Queensland, Australia.
Kyphosis has not been reported in any Graptemys species (map turtles and sawbacks). We captured four kyphotic individuals of Graptemys oculifera from the Pearl River system, Mississippi, with three individuals recaptured 5 to 12 yrs later; one juvenile female had measurable growth, and two adult females had negligible growth. All kyphotic individuals were females, with an overall occurrence rate of 0.10% (4 of 3830 individuals) at five G. oculifera sample sites.
Loggerhead sea turtles (Caretta caretta) feed predominantly on marine crustaceans, mollusks, and other hard-shelled macroinvertebrates. In this note, we report on a subadult loggerhead observed to be feeding on live fish swarming around the turtle in a prey-fish ball. The observation suggests that loggerheads occasionally prey upon certain pelagic fish species other than those encountered as carrion or fishing bait, and may explain accounts of turtles impaled by billfish (Istiophoridae) rostra.
We report the crab species Callinectes sapidus (Decapoda: Portunidae) as a diet item for adult olive ridleys (Lepidochelys olivacea). This is the first-ever report of this species as part of the diet for olive ridley turtles and helps further our understanding of the foraging ecology of this species in coastal marine habitats.
Se reporta la especie de cangrejo Callinectes sapidus (Decapoda: Portunidae) como nuevo ítem alimenticio para tortugas Lora adultas (Lepidochelys olivacea). Este trabajo es pionero en el conocimiento de los hábitos alimenticios de la tortuga Lora en Venezuela.
Five turtle species, Cuora amboinensis, C. mouhotii, Cyclemys gemeli, Melanochelys tricarinata, and Indotestudo elongata, are reported for the first time from the Himalayan Kingdom of Bhutan. The record of C. mouhotii represents a significant range extension to the west; that of C. amboinensis represents a range extension across a political border from the same landscape in adjacent Northeast India; and those of C. gemeli, M. tricarinata, and I. elongata fill geographic gaps in their known distributions. An analysis of distributions of other turtle species in adjacent eastern Nepal and Northeast India suggests that additional country records of turtles may be found in Bhutan, especially in the southern lowlands of the country.
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