Turtle Hatchlings Research Articles

Notes on a Nest and Emergence of Hatchlings of the Euphrates Softshell Turtle (Rafetus euphraticus) at the Dez River, Iran

Abstract We report on a Euphrates softshell turtle (Rafetus euphraticus) nest and hatchlings that emerged from the nest that was constructed in a sand patch of the Dez River in southwestern Iran and discovered on 8 July 2012. Information on nest location and structure and hatchling morphology is presented.

Sex ratio estimations of loggerhead marine turtle hatchlings by incubation duration and nest temperature at Sirte beaches (Libya)

SUMMARY: Hatchling sex ratios in loggerhead marine turtles (Caretta caretta) were estimated on the beaches near Sirte (Libya), using two methods: incubation duration and nest mean temperature during the middle third of the incubation period. Electronic temperature/humidity loggers were deployed at a total of 13 selected nests at Al-Ghbeba, Al-Thalateen, west of Al- Thalateen, Shash and Al-Arbaeen. The incubation period ranged from 47 to 58 days and average temperature ranged from 29°C to 31.8°C. The maximum temperature during this period increased to between 0.6°C and 3.5°C, while the mean temperature also increased during the middle third of the incubation period compared with the first third and continued to increase during the last third. As expected, this study showed that the temperature in the nest decreased with increasing depth of the nest. The results showed a female-dominated sex ratio at 85.4% on the basis of incubation duration and 70.4% on the basis of mean temperature. These findings support the reported highly female-skewed sex ratios in the Mediterranean and elsewhere.

Sea turtle population structure and connections between oceanic and neritic foraging areas in the Atlantic revealed through trace elements

Assessing population structure and connectivity of species that have cryptic life stages, such as sea turtles, is a challenge in conservation biology. The early oceanic stage of sea turtles, also known as the 'lost years', is poorly known. Green turtle Chelonia mydas hatchlings emerge from their nests, enter the sea, and inhabit oceanic (open ocean) habitats where they are rarely seen until they recruit to coastal (neritic) foraging grounds several years later. Therefore, the location of and population structure in oceanic foraging grounds, as well as the connections between oceanic and neritic foraging grounds, are difficult to determine. Given that long-term tracking devices are not available for sea turtle hatchlings, the use of other markers, such as trace elements and stable isotopes, is necessary to study the oceanic stages of sea turtles. We analyzed the elemental composition and ratios of stable isotopes of carbon and nitrogen of scute tissue that was deposited when turtles were in the oceanic habitat to characterize 6 oceanic foraging areas used by green turtles in the Atlantic Ocean. We determined that there is significant structuring among oceanic green turtle aggregations and multiple links between oceanic and neritic foraging areas. We discuss the conservation implications of structured oceanic aggregations with multiple links, as well as the use of trace elements (particularly titanium, chromium, zirconium and barium) in the characterization of oceanic regions.

Rebirth

Rebirth Katie Fallon (bio) A turkey vulture is a perfect creature. It is neither prey nor predator. It exists outside the typical food chain, beyond the kill-or-be-killed law of nature, although without death it would starve. On six-foot wings it floats above our daily lives, waiting for the inevitable moment that will come to each of us, to every living thing. Then the vulture transforms these transformations—these deaths—into life. I was thinking about the circle of life as the elevator door slid open and the attendant wheeled me onto the sixth floor, into the hospital's labor and delivery unit. My husband Jesse followed, laden with several bags of our clothes, an outfit for our soon-to-be-born baby, cameras, and books. One of the bags also contained a charm of sorts—a large black flight feather, recently molted from a turkey vulture we'd been caring for at our nonprofit avian rehabilitation center. The vulture had been caught in an illegally set leg-hold trap, meant for a raccoon or another small mammal; after two surgeries and many rounds of physiotherapy, the bird would be healthy enough to be released in a week or two. In addition to the feather, a pendant depicting Nekhbet, ancient Egypt's vulture goddess, hung from my necklace. [End Page 131] This was probably the first time a vulture feather had been brought into the maternity ward of the university's state-of-the-art hospital. But ancient peoples, including the Egyptians and the Greeks, considered vultures protectors and ideal mothers. Nekhbet, usually shown as a griffon vulture with wings spread and a shen—a symbol of eternity— in her talons, appears on the tombs of pharaohs. A golden Nekhbet sits atop Tutankhamen's death mask, and several elaborate Nekhbet necklaces and collars encircled the young king's neck and shoulders. In addition to shielding the pharaohs, Nekhbet protected mothers and women during childbirth. Perhaps it was the vulture's ability to turn death into life that inspired Nekhbet's role as a kind of supernatural midwife. When our daughter entered the world seven hours later, I was still wearing my Nekhbet pendant. Turkey vultures have an undeserved reputation as dirty, sneaky sorts. Many people find them ugly, disgusting, or worse. They have been accused of killing calves and lambs, though no documented accounts of this exist. It's likely the birds are attracted to livestock giving birth—both turkey vultures and black vultures have been known to eat the placentas of sheep and cows. (I'd wanted to save my own placenta to feed to the turkey vulture in our care, but it was whisked away at the hospital.) The scientific literature on turkey vultures goes to great lengths to document any instances of them taking live prey; these instances are very few and far between, and most involve "unnatural situations," such as birds caught in traps or birds in captivity. The only animals ever proven to be killed by turkey vultures include a ruffed grouse chick, small fish, turtle hatchlings, and perhaps nestlings or sickly birds. If it's available, and it usually is, turkey vultures prefer carrion. A world without avian scavengers is a world imperiled. Vultures decontaminate landscapes by removing dead animals that might otherwise contribute to the spread of disease. A turkey vulture's powerful [End Page 132] digestive system can neutralize dangerous pathogens such as anthrax and botulism. Unlike some mammalian scavengers, vultures do not spread rabies or distemper virus. Vultures are the peaceful recyclers of the animal kingdom, perfectly adapted to cleanse, purify, and renew. My daughter was born clutching the umbilical cord in her little hand. Our midwife let Jesse "catch" the baby. He handed the wiggling, crying, and visibly confused creature to me, and I held her to my chest as she began to root for her first meal. The side of her cheek pressed against me as she squirmed, and I realized the Nekhbet pendant was between us. I slid the pendant over my shoulder as the baby began to nurse. We were naked, the warm, slippery baby and I, and aside from the modern trappings of...

Wood Storks (Mycteria americana) Prey on Eggs and Hatchlings of Olive Ridley Sea Turtles (Lepidochelys olivacea) at Ostional, Costa Rica

Abstract. The foraging behavior of Wood Storks (Mycteria americana) has been studied extensively because of their dramatic population decline and endangered status. The foraging by Wood Storks at an arribada beach with olive ridley sea turtles (Lepidochelys olivacea; turtle) at Ostional, Costa Rica, was examined to determine their depredation behavior on turtle eggs and hatchlings. Wood Storks, in association with Black Vultures (Coragyps atratus), foraged on turtle nests exposed by stream, tidal, and wind erosion, and on nests dug up by dogs (Canis familiaris). Wood Storks also foraged on emerging turtle hatchlings and those crawling to the sea. Wood Storks concentrated near stream beds where nearly half of the predation events (eggs/hatchlings being eaten) occurred. Usually, one to three Wood Storks fed at a turtle nest; an average of 87% of the Wood Storks that were within 5 m of a turtle nest obtained eggs or hatchlings. The number of Wood Storks present and feeding, and the percent feeding, depended ...

Tracking sea turtle hatchlings — A pilot study using acoustic telemetry

Understanding the movements of turtle hatchings is essential for improved understanding of dispersal behaviour and ultimately survivorship, life history strategies and population connectivity. Yet investigation of in-water movement has been hampered by the small size of hatchlings relative to the size of available tracking technologies. This has resulted in the use of labour intensive visual tracking methods, or active tracking methods with high transmitter to body weight ratios. These methods are confounded by the presence of the observer, the size of the tag, usual small treatment sample sizes and studies that are constrained to daylight hours when turtles hatch predominantly at night. Passive acoustic monitoring using new miniature tags can overcome these limitations.We tested the effectiveness of active and passive acoustic tracking in monitoring turtle hatchling movement in order to measure the influence of artificial light on newly hatched turtles once they enter the water. A Vemco VR2W Positioning System (VPS) comprising an array of 18 VR2W receivers was deployed in the surf zone to detect signals from acoustic-coded transmitters (1.14±0.06% of body mass) attached to 26 flatback turtle hatchlings released into the array. A total of 1328 detections were recorded for 22 hatchlings with turtles spending a mean of 16.63±5.89min in the array. The test detection range for this technology in the surf-zone was 50–100m and was influenced by wave noise and shallow deployment. Cyclonic conditions hampered the experiment and resulted in an inconclusive test of light effects. Three additional instrumented flatback hatchlings were followed in a small boat using a mobile acoustic receiver and directional hydrophone up to 2km from shore. Passive acoustic monitoring is a viable technology for tracking small marine animals and removes many of the confounding effects of other telemetry methods. It has great potential to examine natural and anthropogenic factors influencing orientation and behaviour during a crucial stage in turtle life history — their initial movement from the beach through predator-rich, near shore waters. While the data obtained by passive acoustic monitoring is limited in its spatio-temporal coverage, being constrained by the size of the array, active acoustic tracking can be applied over larger scales. Such studies will be particularly important for assessing the impacts of anthropogenic pressures that have changed the natural light, noise or wave environments and for providing behavioural data to improve and validate bio-physical models of the migration and dispersal of young turtles.

Post-Emergence Behavior of Hatchling Western Pond Turtles (Actinemys marmorata) in Western Oregon

Abstract Understanding space-use patterns of freshwater turtle hatchlings is critical to guide conservation efforts, yet little is known because of the difficulties in studying this early life-history stage. We investigated post-emergence movements and habitat associations of western pond turtles (Actinemys marmorata) at two study sites in western Oregon using micro-transmitters and harmonic radar methods. Hatchlings delayed emergence until spring, with few exceptions. Hatchlings typically remained within 2 m of nests for as long as 59 d after initial emergence. During migration from their nests to aquatic habitat, hatchlings embedded themselves in soil for up to 22 d at stop-over sites. Movements between successive stop-over sites averaged 27 m. Although the number of days turtles remained within 2 m of their nest following emergence varied widely among and within nests, hatchlings entered aquatic habitat relatively synchronously. Hatchlings entered aquatic habitat on average 49 d after initial emergence...

Post‐emergence handling of green turtle hatchlings: improving hatchery management worldwide

AbstractHatcheries are commonly used to protect sea turtle eggs from poaching and predation; however, there is currently limited scientific evidence to support good hatchery management practices, particularly post‐hatching. This study investigated the effects of retaining hatchlings in hatcheries after emergence and delaying nest excavations on the quality of green turtle Chelonia mydas hatchlings. In addition, the effect of artificial lighting on the sea‐finding ability of green turtles was investigated to highlight the importance of hatchling release locations on hatchery beaches. Hatchling running speed, an indicator of vigour and predation exposure, progressively decreased when hatchlings were retained in the hatchery for 1, 3 and 6 hours following emergence. Similarly, body condition (mass : straight carapace length), an indicator of dehydration and/or energy consumption, decreased after being retained for 3 and 6 hours. It was estimated that hatchlings retained for 6 hours after emergence would become significantly dehydrated and double their exposure to beach slope predation. Residual hatchlings that were immediately excavated from emerged nests had similar running speed and body condition to naturally emerged siblings. However, residual hatchlings removed from nests 5 days later had significantly reduced running speed and body condition, resulting in estimates of double the exposure to predation in near‐shore areas. The mean angle of hatchling dispersal varied at different sites along the Ma’Daerah beach in relation to proximity to artificial lighting. Important recommendations for post‐hatching management of sea turtle hatcheries worldwide can be made from the results of this study. To maximize release of hatchlings in the best condition as is possible, hatchlings should be released immediately after emergence, including excavation of any residual hatchlings. In addition, the dispersal angles of hatchlings should be tested at each hatchery beach to determine suitable release sites for efficient dispersal.

Does maternal oviposition site influence offspring dispersal to suitable habitat?

Orientation and dispersal to suitable habitat affects fitness in many animals, but the factors that govern these behaviors are poorly understood. In many turtle species, hatchlings must orient and disperse to suitable aquatic habitat immediately after emergence from subterranean nests. Thus, the location of nest sites relative to aquatic habitats ideally should be associated with the direction of hatchling dispersal. At our study site, painted turtles (Chrysemys picta) nest to the west (on an island) and east (on the mainland) of a wetland, which determines the direction that hatchlings must travel to reach suitable aquatic habitat. To determine if hatchling orientation is intrinsically influenced by the location where their mothers nest, we employed a two-part cross-fostering experiment in the field, whereby half the eggs laid in mainland nests were swapped with half the eggs laid in island nests. Moreover, because C. picta hatchlings overwinter inside their nests, we performed a second cross-fostering experiment to fully decouple the effects of (1) the maternally chosen nest location, (2) the embryonic developmental location, and (3) the overwinter location. We released hatchlings into a circular arena in the field and found that turtles generally dispersed in a westerly direction, regardless of the maternally chosen nest location and independent of the locations of embryonic development and overwintering. Although this westerly direction was towards suitable aquatic habitat, we could not distinguish whether naïve hatchling turtles (i) use environmental cues/stimuli to orient their movement, or (ii) have an intrinsic bias to orient west in the absence of stimuli. Nevertheless, these findings suggest that the orientation behavior of naïve hatchling turtles during terrestrial dispersal is not dependent upon the location of maternally-chosen nest sites.

Conservation implications of density-dependent predation by ghost crabs on hatchling sea turtles running the gauntlet to the sea

Protecting eggs from predators is common practice in sea turtle conservation, but routine protection of hatchlings is not. Of 42 loggerhead hatchlings observed emerging from 10 nests on undeveloped Onslow Beach, North Carolina, 24 % were preyed on by ghost crabs. In experimental trials, ghost crabs similarly threatened and captured neonate freshwater sliders, supporting their substitution as proxy for threatened and endangered sea turtle hatchlings in field experiments testing density dependence. Exploiting natural long-shore variation in ghost crab density, we show that a 2.6-fold higher ghost crab density resulted in 5 times more nocturnal threat encounters with sliders and 3.4 times more slider captures. Sliders released in simulated group emergences experienced lower per capita capture risk by ghost crabs than solitary sliders, implying predator dilution. Non-independence of egg and hatchling depredation motivates consideration of merging sea turtle egg and hatchling stages when modeling and managing food web interactions.

The dark side of light. Light pollution kills leatherback turtle hatchlings

The leatherback turtle is the largest and most migratory of all sea turtles and deepest diving air-breathing animal. It has unique physiology which allows it to adapt to various habitats ranging from sub-polar to equatorial during its migrations. The leatherback turtle is also the only sea turtle where no cases of tumours have been diagnosed. These unique features add to the arguments for preservation of this endangered species. Here we discuss the effect of light pollution on leatherback turtle hatchlings in Tobago and the measures for their protection.

Effects of off-road vehicle tyre ruts on the beach dispersal of green sea turtle Chelonia mydas hatchlings

The use of off-road vehicles (ORVs) on sandy beaches creates ruts in the sand that may interfere with the beach dispersal of sea turtle hatchlings. The present study investigated the influence of simulated ORV ruts of 3 depths (5, 10 and 15 cm) on the success and speed of green sea turtle Chelonia mydas hatchling dispersal. Almost all hatchlings (91%) were unable to tra- verse a single 15 cm rut, indicating that ruts of this depth are particularly detrimental to hatchling dispersal. Hatchlings had greater success traversing the 5 and 10 cm ruts, although they spent 2.6 and 18.6 times longer to get through a single rut, respectively (compared to the flat sand control path). It took progressively longer to get through subsequent ruts, and 99 and 53% of the hatch- lings crawled along the 10 and 5 cm ruts, respectively, instead of attempting to crawl out of them. It was estimated that if hatchlings had to traverse 100 ORV ruts during dispersal, it would take 1.9 and 25.1 h for 5 and 10 cm deep ruts, respectively. The results from the present study indicate that green sea turtle hatchlings would spend considerable time navigating through ORV ruts, even as shallow as 5 cm, resulting in increased exposure to predation, dehydration and energy expendi- ture during this initial stage of dispersal.

Isolation and Characterization of Chelonia mydas Myoglobin

Green sea turtle – Chelonia mydas is a lung respiration animal that is able to dive and stay uder sea water for hours without needing to surface for oxygen. As oxygen supply in muscles is assured by myoglobin, we propose to study some characteristic of this muscle protein in green sea turtles. To achieve this objective, pure green sea turtle myoglobin has to be made available. Therefore, our first task is to purify this muscle protein from green sea turtles. Skeletal muscles from 3 green sea turtle hatchlings were studied microscopically and biochemically. Microscopy observation showed a general structure of striated muscle. Biochemical studies revealed that green sea turtle myoglobin could be more purely isolated to a certain degree by Sephadex G-75 gel filtration and purified by immunoaffinity gel chromatography rather than direct purification by DEAE-Sepharose ion exchange chromatography technique. SDS-PAGE analysis showed that green sea turtle myoglobin ran together with horse myoglobin as 17 kDa molecular weight proteins.

Beach Condition and Marine Debris: New Hurdles for Sea Turtle Hatchling Survival

Abstract The dash of freshly emerged hatchlings to the sea is a short but critical phase in the life cycle of sea turtles. We examine the time spent on a Mediterranean beach from the perspective of substrate composition and temperature, marine debris, and hatchling crawling speeds and times. Crawling speeds depended on beach quality. The hatchlings crawled significantly faster on sand than on cobbles, and cooler temperatures considerably prolonged the crawls. Marine debris was a major impediment: hatchlings were severely entangled in fishing nets and entrapped in simple containers such as plastic cups and cut-open canisters. They never avoided contact with such experimentally deployed debris or reversed their direction to escape. The overall debris density at the study site averaged 1.03 items m−2, mostly plastic, and 2 out of 3 hatchlings had contact with such debris on the way to the sea. Marine debris is a new aspect of habitat quality for sea turtle nesting site monitoring and conservation efforts and...

SWIMMING HELPS SIMULATED TURTLES STAY ON COURSE

Pitched against the mighty North Atlantic, it would seem that newly hatched loggerhead turtles would stand little chance of influencing their destiny. Perceived wisdom held that after swimming from their home beach the youngsters got picked up by the powerful currents circulating in the North Atlantic, where they could spend as much as the next 15 years being carried around the ocean. However, Nathan Putman and Ken Lohmann from the University of North Carolina, USA, were less sure. Together with other colleagues, they had already shown that simulations of the magnetic field from various locations in the North Atlantic affected the tiny animals’ choice of direction, with the minute migrants selecting the best orientation to keep them in the circulating current. However, many ecologists did not believe that the hatchlings’ efforts could influence their North Atlantic odyssey. Intrigued, Putman and Lohmann decided to take a computational approach; they set millions of cyber-turtles loose in a simulated North Atlantic to find out how much they affect their own course (p. 1863).‘We wanted an ocean model that would depict weather events that were forced using wind, so getting a model that was very fine scale was important for those fine scale little animals’, says Putman. So, the duo teamed up with oceanographer Thomas Shay from the University of North Carolina, USA, to simulate 5 years of ocean circulation. Then, having successfully constructed their cyber-ocean, they had to figure out how to simulate the turtle voyagers. ‘We came across Philippe Verley, who devised this wonderful software that was called ICTHYOP that was designed to study the movement of fish larvae’, explains Putman. Visiting Verley at the Laboratoire de Physique des Océans in France, Putman and Verely discussed how they could convert the fish simulations into turtles migrating through the ocean. After a number of modifications to the software, Putman was ready to set hundreds of thousands of simulated turtle hatchlings loose in the cyber-ocean.Setting the youngsters to swim for 1, 2 or 3 h per day at 0.2 m s–1, the program allowed the turtles to drift with the current for the remainder of the day. Then, when the turtles entered specified regions of the ocean, the program allocated them a swimming direction in roughly the same orientation that the young turtles had selected in the laboratory. ‘We were interested in modelling realistic navigation behaviour so we wanted a wide spread of around 80 deg around the directions that the hatchlings had picked’, explains Putman.After months of computation and analysis, the duo realised that even the most minimal amount of swimming had affected the simulated hatchlings’ trajectories. Comparing the swimming turtles with simulations of turtles that drifted exclusively, the duo could see that the courses of the swimming turtles were less dispersed than those of the turtles that had been cast purely to the sea. ‘The swimming behaviour seemed to be compensating for the tendency of dispersion. It’s like the turtles were swimming to make the currents approximate what we see in the textbooks’, says Putman.Having found that swimming for even a tiny fraction of a day could help the simulated turtles stay on course, the duo is keen to track the progress of recently embarked hatchlings to find out how much of an impact swimming makes in practice. ‘The plan is to put tiny little tags on turtles. We’ll know where the turtle goes, but it won’t tell us if they are swimming or drifting, so we’ll look at the ocean circulation models along the turtles’ paths and subtract the current velocity to determine when they are swimming’, explains Putman.

Terrestrial habitat requirements of nesting freshwater turtles

Because particular life history traits affect species vulnerability to development pressures, cross-species summaries of life history traits are useful for generating management guidelines. Conservation of aquatic turtles, many members of which are regionally or globally imperiled, requires knowing the extent of upland habitat used for nesting. Therefore, we compiled distances that nests and gravid females had been observed from wetlands. Based on records of>8000 nests and gravid female records compiled for 31 species in the United States and Canada, the distances that encompass 95% of nests vary dramatically among genera and populations, from just 8m for Malaclemys to nearly 1400m for Trachemys. Widths of core areas to encompass varying fractions of nesting populations (based on mean maxima across all genera) were estimated as: 50% coverage=93m, 75%=154m, 90%=198m, 95%=232m, 100%=942m. Approximately 6–98m is required to encompass each consecutive 10% segment of a nesting population up to 90% coverage; thereafter, ca. 424m is required to encompass the remaining 10%. Many genera require modest terrestrial areas (<200m zones) for 95% nest coverage (Actinemys, Apalone, Chelydra, Chrysemys, Clemmys, Glyptemys, Graptemys, Macrochelys, Malaclemys, Pseudemys, Sternotherus), whereas other genera require larger zones (Deirochelys, Emydoidea, Kinosternon, Trachemys). Our results represent planning targets for conserving sufficient areas of uplands around wetlands to ensure protection of turtle nesting sites, migrating adult female turtles, and dispersing turtle hatchlings.

Swimming performance and metabolic rate of flatback Natator depressus and loggerhead Caretta caretta sea turtle hatchlings during the swimming frenzy

Swimming performance influences the dispersal success of sea turtle hatchlings when they first enter the water and engage in a 'swimming frenzy' which moves them rapidly offshore. We simultaneously measured swim thrust (in millinewtons, mN) and metabolic rate (in milliwatts, mW) of loggerhead Caretta caretta and flatback turtle Natator depressus hatchlings during the first 18 h of the swimming frenzy and compared the results with previous data from green turtle Chelonia mydas hatchlings. Metabolic rate was correlated with swim thrust in all species. In all species, swim thrust decreased sharply during the first 2 h of swimming, continued to slowly decrease until 12 h and remained constant at this lowest level until experiments ended at 18 h. Metabolic rate had a similar pattern, with a steep drop during the first 2 h followed by a less steep decrease before becoming relatively constant. Swim thrust and metabolic rate were highest in green turtle hatchlings. Flatback hatchling metabolic rate was similar to green turtle hatchlings but they weighed almost twice as much, while loggerhead hatchlings had the lowest metabolic rate. Flatback hatchling swim thrust decreased the fastest, falling below that of green turtle hatchlings within the first hour of swimming and falling below loggerhead turtle hatchlings after 12 h of swimming. These findings suggest that flatback hatchlings have a different dispersal behaviour compared to green and loggerhead hatchlings. The shorter highly vigorous swimming period of flatback turtles might be explained by the fact that they do not swim into off-shore oceanic dispersing currents, and managing their energy resources might be a strategic adaptation to survive predators in a relatively constant environment.

Integrated risk factors for vertebrate roadkill in southern Ontario

AbstractRoad mortality of animals (roadkill) threatens public safety and wildlife populations. As mitigation tools, predictive models of roadkill are becoming more common in the published literature; however, few models generalize across multiple taxa, and thus are less useful for management scenarios that account for multiple target species. Using a dataset of 653 vertebrate roadkills collected from 2 parks in southern Ontario, we constructed generalized linear mixed models to determine the simultaneous risk factors for bird, frog, mammal, five‐lined skink (Eumeces fasciatus), snake, toad, and turtle hatchling roadkills from among a set of 8 potential predictor variables. Posted road speed limit was the dominant roadkill predictor (positive coefficient), followed by maximum daily temperature (positive), habitat diversity (positive), and distance from wetlands (negative). All else being equal, as road speed limits increase from 20 km/hr to 50 km/hr, the model predicted the season's mean roadkill probability for a given location to increase from less than 0.1 to 0.75. Conversely, roadkill probability declined from 0.55 to 0.29 as distance from wetland edges increases from 0 km to 1 km. Model diagnostics calculated from randomly resampled cross‐validation datasets indicated that the best model formulation had an averaged predictive accuracy of 67.5% and an area under the curve (AUC) of 0.867. The best model also reflected seasonal patterns of animal behavior, including late‐summer frog movements and fall turtle hatching events. The best model also compared favorably to single‐taxon equivalent models. To reduce the incidence of vertebrate roadkill, we recommend that managers lower road speed limits, especially on roads near diverse habitats and near wetlands, and on warmer days if temporary signage is used. © 2012 The Wildlife Society.

Australian Loggerhead sea turtle hatchlings do not avoid yellow

When emerging from the nest, sea turtle hatchlings primarily orient using visual stimuli, with light pollution known to disrupt effective sea localization behavior. Previous studies have shown that sea turtle hatchlings respond differently to different wavelengths of light but Loggerhead hatchlings, exclusively among species tested, have a strong aversion to yellow light (at 600 nm). This study repeats these experiments with an Australian population of Loggerhead hatchlings (Caretta caretta) and Flatback hatchlings (Natator depressus). The orientation preference was measured using a modified y-maze set-up with the animals response observed using an infrared camera. This study showed that both Loggerhead and Flatback hatchlings can see and are attracted to light in the ultraviolet waveband (365 nm) and, to a lesser extent to longer wavelengths of 600 nm and above. The surprising finding was that the Loggerhead hatchlings tested here, unlike their conspecifics in Florida, do not show any avoidance to yellow but are attracted to bright lights of wavelength between 365 nm (UV) and 600 nm. This suggests potential differences in the visual behavior among different populations of sea turtles of the same species. No difference was detected in the response of Loggerhead hatchlings to flickering or steady light stimuli.

On the dispersal of leatherback turtle hatchlings from Mesoamerican nesting beaches

So little is known about the early life history of leatherback turtles (Dermochelys coriacea) from hatchling to adulthood that this period has been termed the ‘lost years’. For critically endangered eastern Pacific leatherback populations, continued and rapid declines underscore the urgent need to develop conservation strategies across all life stages. We investigate leatherback hatchling dispersal from four Mesoamerican nesting beaches using passive tracer experiments within a regional ocean modelling system. The evolution of tracer distribution from each of the nesting beaches showed the strong influence of eddy transport and coastal currents. Modelled hatchlings from Playa Grande, Costa Rica, were most likely to be entrained and transported offshore by large-scale eddies coincident with the peak leatherback nesting and hatchling emergence period. These eddies potentially serve as ‘hatchling highways’, providing a means of rapid offshore transport away from predation and a productive refuge within which newly hatched turtles can develop. We hypothesize that the most important leatherback nesting beach remaining in the eastern Pacific (Playa Grande) has been evolutionarily selected as an optimal nesting site owing to favourable ocean currents that enhance hatchling survival.