We studied reproduction and nesting of the keeled box turtle (Cuora mouhotii) during 2003 and 2009 on Hainan Island, China. We found the first gravid turtle on 28 April and nesting was from May until July, with a peak in mid-June. We observed the first fresh nest on 1 June and last fresh nest on 27 July. Some females laid eggs from 1 clutch in 2 batches. Clutch size ranged from 1 to 5. Mean egg measurements were as follows: length, 4.5 cm; width, 2.7 cm; and mass, 19.8 g. There was no significant relationship between turtle body size (mass, length, height, and width) and clutch size or egg size (mass, length, and width). Clutch size was significantly correlated with the egg mass and egg width. Possible low fertility, low hatching rate, and the long period to reach maturity imply that C. mouhotii has a low intrinsic rate of population increase. This, combined with overcollecting and habitat destruction, requires development of more effective conservation strategies for this endangered species.

When Aldabra Atoll became a nature reserve in 1968, its endangered nesting green turtle (Chelonia mydas) population was the first to be protected in the Indian Ocean. In 1983, Aldabra became a UNESCO World Heritage Site managed by the Seychelles Islands Foundation (SIF). But prior to 1968, its green turtles suffered intense exploitation documented by trade statistics, historical literature, and a scientific study in 1927. Three population surveys conducted just before, during, and shortly after 1968 provide baseline data by which to assess the long-term population recovery monitored since 1980 using a standardized track count protocol. The 52 nesting beaches distributed along the 83-km outer rim of Aldabra were classified into 6 beach groups (WGT, SETT, DDM, DJL, CC, and North), with total beach length of 5.2 km. During Phase 1 (1980–1994) of the study, 17 index beaches (WGT #1–17) were monitored 4 times per month and other beaches opportunistically. During Phase 2 (1994–2008), index beaches (WGT #1–22 and SETT) were monitored at least 4 times per month and remote beaches monthly. Track counts were converted to estimated egg clutch production using nesting success data. Reproductive output for the atoll rose from a mean annual estimated 2000–3000 clutches in the late 1960s to 15,669 (SD  =  2776) during 2004–2008, equivalent to a mean estimated 3100–5225 females nesting annually (assuming an average of 3–5 egg clutches per female). This represents a 500%–800% increase during 40 years of complete protection. During Phase 2, the rate of increase was highest at the Settlement Beach (SETT), which had historically suffered the most intense exploitation.

Bioko Island, part of Equatorial Guinea, has been classified as a critically important nesting site for sea turtles in the Gulf of Guinea. However, construction of a road through a previously undeveloped scientific reserve is set to dramatically alter human interactions with nesting turtle populations. This article reports on the current status of sea turtle conservation and research on Bioko Island as well as recent economic considerations that affect local turtle conservation and use.

There is evidence that suggests that most animals rely to some extent on odor detection for finding food, selecting homes and/or egg laying sites, avoiding predators, and selecting mates. A noninvasive way to estimate particular species' utilization of their olfactory receptor system is to sequence olfactory receptor genes and estimate the percentage of these genes that are functional. This method was used to estimate the degree of the olfactory receptor system use in 7 turtle species (Dermochelys coriacea, Caretta caretta, Chelonia mydas, Chrysemys picta bellii, Sternotherus odoratus, Terrapene Carolina, and Gopherus polyphemus), the results of which show a trend toward a reduction in the number of odorants that they can perceive as their association with water increases.

Basking is an understudied aspect of turtle biology, especially considering how frequent and observable it is in some species. Researchers have suggested many physiological roles that basking likely fulfills in turtles. We documented seasonal basking behavior of the yellow-blotched sawback (Graptemys flavimaculata) on the Leaf River, a tributary of the Pascagoula River in southeastern Mississippi. We used binoculars and a spotting scope to determine G. flavimaculata individual- and population-level basking patterns throughout the main active months (April–October) and across the daily activity period; we also describe a new method to determine population basking percentage that may be useful for future aquatic turtle surveys. We found distinct differences in individual- and population-level basking behavior across months, sexes, and the daily activity period. We also documented differences in basking structures used between the sexes but found little correlation between population-level basking and several environmental temperature variables.

This paper describes predation tactics used by the saltwater crocodile (Crocodylus porosus) on flatback (Natator depressus) and olive ridley (Lepidochelys olivacea) sea turtles on nesting beaches in northern Australia. For adult turtles, crocodiles used both a sit-and-wait tactic in which they attacked a turtle at the water's edge after it completed nesting and an active hunting strategy in which crocodiles followed turtle tracks into the dunes to attack turtles at nest sites. Saltwater crocodiles also hunted sea turtle hatchlings in the dunes and excavated a sea turtle nest and consumed the eggs. The protection of saltwater crocodiles in Australia starting in the early 1970s has led to increased population sizes and a greater proportion of larger individuals. This likely has resulted in increased predation rates on sea turtles over several decades, which should be considered as an important mortality component for some tropical nesting aggregations.

We studied reproductive parameters and noted predation of Phrynops geoffroanus nests along the Guaporé River of the Brazilian and Bolivian Amazon during the beginning of the falling water level season (vazante) in July 1989 and 2008. We searched for nests on the banks of the Guaporé River every morning navigating by outboard along the Guaporé River between Divisa sector state of Rondônia in Brazil and Versalles village, Department El Beni in Bolivia. We found 10 nests in 1989 and 46 nests in 2008. Clutch size ranged from 7 to 16 eggs and was larger in 2008. There was no relationship between egg size and nest size or the size of eggs between year 1989 and year 2008. The predation rate in 2008 was 89.1%, all depredated by the lizard Tupinambis teguxin. Habitat loss for the lizard may be creating habitat utilization shifting and increased turtle nest depredation rates.

Habitat features influence the distribution and abundance of marine animals and are used to identify critical areas to protect threatened marine species. In this study, we surveyed juvenile hawksbill turtles in 5 localities of the Culebra Archipelago, Puerto Rico; described the habitats using cover of benthic features; and related relative abundance of turtles among localities with food availability. We tested the hypothesis that variability in turtle abundance among study sites was related to spatial variability in the availability of diet items. Our results point out that spatial variability in turtle abundance is not related to food availability by itself; rather, the structural complexity and types of benthic structure played a more important role in explaining the turtles' local abundance. The importance of structural complexity is most likely related to sheltering.

We report emergence dates for 38 alligator snapping turtle (Macrochelys temminckii) hatchlings from 6 naturally incubated nests laid during the 2008 and 2009 nesting seasons in northeastern Louisiana. Per capita emergence success for 2008 and 2009 combined was 19.5%. Hatchling emergence occurred from 28 August to 25 September and was asynchronous for 80% of nests that had multiple hatchlings emerge, with emergence duration as long as 12 days. We found no evidence of delayed emergence; some hatchlings may remain in the nest for up to 3 weeks before successfully emerging.

Population monitoring and evaluation of spatial requirements of species are key actions for the conservation of wild populations, especially for endemic and threatened species. We estimated the abundance of the endemic species Mesoclemmys dahli in 2 streams in Cesar, Colombia, from February 2008 to February 2009, by using aquatic sampling. We monitored fluctuations in abundance through the year and used mark–recapture sampling and the Jolly–Seber model to estimate population size and density. Home ranges and movement patterns were studied by using very high frequency (VHF) radio telemetry. We calculated home ranges for the year and for the wet and dry season independently. Estimated population size for the 2 streams varied during the year from 16 (95% CI, 7–30) to 175 (95% CI, 32–298) turtles. Densities ranged from 16 turtles/ha in April to approximately 170 turtles/ha in June, which is lower than other populations of M. dahli in Colombia as well as other South American chelids. Individuals captured during the wet season had a significantly higher mean body mass than those captured during the dry season, which suggests that larger animals may leave the streams during the dry months or that animals may lose weight during this period. Home ranges for 1 year varied from 1.6 to 30.8 ha when using the minimum convex polygon method and from 9.2 to 22.5 ha when using the fixed kernel density estimator. There were no significant differences in the mean movements during the dry and wet seasons. However, the greatest movements were documented either during the transition from wet to dry months or during the dry months. Conservation of M. dahli will require protection of the few streams where it occurs, as well as the associated riparian vegetation and surrounding areas used by the species.

Reeves' pond turtle, Mauremys reevesii, is an aquatic geoemydid species that is broadly distributed in East Asia. Like many other Asian turtles, this species is facing an extinction crisis in most countries where it occurs. In Japan, however, this turtle commonly occurs in various freshwater habitats. Although the Japanese populations have generally been considered to be native, a few recent studies have yielded circumstantial evidence that suggested that they had originated from relatively recent artificial introductions from abroad. To evaluate the validity of such a view, we analyzed sequence variations of the mitochondrial cytochrome b gene and the control region in M. reevesii samples from various localities in Japan and adjacent countries. The results revealed the presence of 3 distinct genetic groups (groups A, B, and C) in the Japanese samples, of which groups A and B included haplotypes that were almost identical with some haplotypes from the Korean sample and the Chinese and Taiwanese samples, respectively. Sequences from M. reevesii shell products commercially traded in Taiwan included one that was almost identical to the group C sequence. The current Japanese populations of M. reevesii seem to have been derived from multiple artificial introductions from adjacent countries. This finding implies a need to be concerned about the effect of M. reevesii on the Japanese native wildlife, particularly on the Japanese endemic pond turtle, Mauremys japonica, with which M. reevesii is phylogenetically closely related and reportedly frequently hybridizes in the wild. However, the Japanese population may be useful as a genetically variable stock for conservation of this species, which is highly endangered in most of its range outside Japan.

Hematologic data, morphology, and ultrastructure of peripheral blood cells of 5 juvenile olive ridley turtles (Lepidochelys olivacea) were evaluated. The following blood cells were identified: mature and immature erythrocytes, heterophils, large and small eosinophils, basophils, lymphocytes, monocytes, and thrombocytes. Unique blood cell features of olive ridley turtles that are useful for health evaluations within sea turtle care and conservation were identified in hematologic, morphological, and ultrastructural studies.

We studied 11 nests, and the resulting neonates of Eastern Box turtles (Terrapene carolina) in New York in 2001 and 2002, and documented neonate emergence and movements. None overwintered in the nest; instead, they emerged in the fall and overwintered buried shallowly close to the nest, where they were exposed to temperatures as low as −7°C. Further research is needed regarding neonate T. carolina behavior and the relative advantages of overwintering in the nest and overwintering terrestrially outside the nest.

We studied the home range and habitat use of northern map turtles (Graptemys geographica) in Québec, Canada, in a river comprised of multiple channels and islands. To better represent the home range of turtles in such complex river landscapes, we developed the complex linear home range (CLHR), a generalized estimator designed to more accurately represent turtle home ranges based on their movements in multiple channels, unlike the simple well-known linear home range and the minimum convex polygon estimators. The CLHR appears to be an estimator that can permit the interstudy comparison of turtle home ranges in other rivers characterized by multiple channels and can be calculated easily using GIS software.

The chemical elements of green turtle (Chelonia mydas) eggshells collected from Samandağ Beach (Turkey) were studied to determine differences between elemental composition and changes in physical characteristics. Eggshells from various developmental stages (n  =  67), from successfully hatched eggs (n  =  25) and infertile eggs (n  =  18) were examined using inductively coupled plasma–atomic emission spectroscopy to determine elemental changes during embryonic development. Through the course of egg development, we found changes in concentration of calcium, copper, potassium, sodium, strontium, and zinc but no changes in magnesium.

We studied nesting site preferences and hatching success of loggerhead (Caretta caretta) and green turtles (Chelonia mydas) on Akyatan Beach, Turkey. The distribution of nests varied annually, with green turtles nesting most often in vegetated areas and loggerhead turtles most commonly in nonvegetated areas. Green turtle hatching success was higher at vegetated vs. nonvegetated nest sites (p < 0.001).

The occurrence of hypomelanism in a population of Irwin's turtles (Elseya irwini) was found to affect only adult turtles (approximately 10%), primarily females. Its complete absence in immature and hatchling turtles indicates that the condition develops ontogenetically through the progressive, localized loss of specific types of chromatophores. Hypomelanistic females were lacking in a variety of pigments affecting virtually all parts of the body and appeared to represent extreme forms of the natural depigmentation process that accompanies maturation in this species.

Understanding reproductive biology is important to elucidate the ecology and life history of animals and is needed to predict population dynamics and demography for conservation. The loggerhead turtle (Caretta caretta) is an endangered sea turtle species, and the vast majority of what is known about their reproductive biology has been learned from nesting females, with little information available on mature males and the time before reaching maturation. In order to increase the understanding about biology of maturation, size at maturity and puberty and the relationship between tail elongation and sexual maturation in loggerhead turtles in the North Pacific Ocean were investigated. The maturity stages of 54 males and 106 females, mostly captured at Kochi and Mie prefectures, Japan, were determined on the basis of gonadal development. There is no significant size difference between males and females in all maturity stages. The straight carapace length notch to tip (SCLn-t) at maturity was estimated as 82.1 cm. Tail elongation is the main secondary sexual characteristic of mature males. The elongation appears to begin when a male reaches to 65.8 cm in SCLn-t. The SCLn-t coincides with the size at puberty, which was estimated as 66.0 cm in this study.

Kemp's ridley sea turtle (Lepidochelys kempii) age at first nesting is the age at which an individual female successfully nests for the first time. This commentary recommends determination of the statistical distribution of age at first nesting, estimation of central tendency, and variability of age at first nesting, and application of these estimates in future age-based and life stage–based demographic modeling, as substitutes for parameter estimates based on age at sexual maturity or age at first reproduction. We hope that our commentary will encourage discussion and research on age at first nesting and its application to demographic modeling of the Kemp's ridley population.