Hatchling Emergence Research Articles

Why do female desert lizards construct burrows to lay eggs?

Many oviparous animals construct well-designed nests to provide relatively favourable conditions for their eggs and hatchlings, but the direct evidence that nest structure can determine their reproductive success is insufficient. In the present study, we explored the structure of nests and its effect on nest environments and reproductive success in the toad-headed agama (Phrynocephalus przewalskii). We observed that female P. przewalskii constructed burrow nest consisting of an inclined tunnel and an expanded chamber. We constructed artificial nests with or without the burrow to determine how burrows influence nest environments, egg survival and successful emergence of hatchlings. Our results indicated that burrow nests had higher and more stable humidity than non-burrow nests. More importantly, egg survival and the emergence success of hatchlings were significantly higher for burrow nests than for non-burrow nests. Therefore, our manipulation experiments provide direct evidence that maternal nest construction behaviour could determine parental reproductive success in reptile.

Effect of heavy metals on the survival, growth and development of earthworm Eisenia fetida

The present laboratory study was carried out to determine the effect of the metal contaminated soil on the survival, growth and development of Eisenia fetida. Metal contaminated soil samples were collected from five different sites of Ludhiana city which is an industrial hub of Punjab. Maximum heavy metal concentrations were recorded in soil sample taken from hambran around the Buddha Nullah and minimum concentration of heavy metal from haibowal. The level of heavy metals chromium and nickel (347 ppm and 189 ppm) were higher than permissible limits according to CCME (2001), whereas lead (42.6 ppm) was within permissible limits. Adult E. fetida were exposed to different concentrations of heavy metals in artificial soil for 28 days. Significant effects were observed on growth and reproduction of the tested organisms. There was 100% survival of E. fetida in soil amended with lead, chromium and nickel along with morphological abnormalities such as extrusion of coelomic fluid. It was observed that the worms in the low and high doses of heavy metal treated substrate produced cocoons with a one week and two week delay, respectively, vis-a-vis the control group. Furthermore, the emergence of hatchlings started one week earlier in control than in soil treated with medium and high concentration of metals. It is safely concluded that presence of heavy metal in soils adversely affects the growth, reproduction and development of E. fetida. Results ofthe study indicated that reproduction was more sensitive to higher concentrations of heavy metal contaminated soil than survival or weight change.

Mid-incubation relocation and embryonic survival in loggerhead sea turtle eggs

Relocations of sea turtle nests are generally performed within 12 hours of deposition to avoid damaging fragile respiratory membranes as they attach to the egg. In May 2007, a tropical storm on the east coast of Florida resulted in severe dune erosion and permission was given for beach and dune restoration. Nests already located on the beach, or that were laid prior to project commencement, were relocated at times varying between 10 days and 38 days post-deposition. This provided an opportunity to examine egg mortality in loggerhead sea turtle (Caretta caretta) nests moved during this critical time period, and determine whether there was a correlation between the relocation and the timing of arrested egg development; we compared hatching and emergence success to nests relocated during the standard initial 12 hours post-deposition and those left in situ. Following hatchling emergence, we collected remaining unhatched eggs to determine development stage at the time of embryonic death. Mean hatch success was 53% for nests moved mid-incubation, versus 79–90% for nests left in situ or moved within 12 hours of deposition. For 6 of 10 nests, embryonic development ceased at the same visual developmental stage as the relocation. Although moving nests later than 12 hours decreases nest success and should be a matter of last resort, the forecasts for increased storm activity and sea level rise, and other impacts such as beach oiling, may necessitate nest relocation under less than ideal circumstances. Choice of relocation site may also be significant; nests placed in native sand had lower emergence success than those moved to the renourished area. © 2015 The Wildlife Society.

Effects of metal contaminated soils on Eisenia fetida (Savigny) at Ludhiana (Punjab), India

The soil in the vicinity of stream of Buddah Nullah in Ludhiana, Punjab has been found to be contaminated with heavy metals. The objective of this paper was to conduct studies with earthworm Eisenia fetida (Savigny) exposed to five soil samples collected from different sites around the stream of Buddah Nullah, since no such work has been done using earthworm as bio- indicator of soil pollution in that area to check the hazardous effects of heavy metals on soil organisms. Metal levels were recorded higher in contaminated soil samples than threshold concentration in soil of campus field. Adult E. fetida were exposed for a period of 80 days to evaluate the effects of elevated levels of heavy metals i.e.0.29 ppm, 4.18 ppm and 2.29 ppm for cadmium, lead and nickel respectively on survival, growth, morphology and reproduction. Significant effects were observed on survival, growth and reproduction of the tested organisms along with various morphological abnormalities such as tail shedding, body fragmentation and extrusion of coelomic fluid. But no such deformity was observed in worms reared in reference soil of university campus field. Detrimental effects on rates of cocoon production and hatchling emergence were observed and a significant delay was also recorded in production of cocoons and emergence of hatchlings. Results of the study indicated that reproductive end points were more sensitive to elevated metal levels in contaminated soil than survival or weight change.

Cues used by predators to detect freshwater turtle nests may persist late into incubation

Previous studies have found that turtle nest depredation is concentrated immediately post-oviposition, likely because cues alerting predators to nest presence are most obvious during this time. In Algonquin Provincial Park, Ontario, we examined the frequency of nest depredation during the incubation period for Snapping Turtles (Chelydra serpentina [Linnaeus, 1758]) and Midland Painted Turtles (Chrysemys picta marginata [Agassiz, 1857]). Contrary to most past findings, nest depredation occurred throughout the incubation period for both species. In fact, 83% and 86% of depredation interactions with Snapping and Painted Turtle nests, respectively, occurred more than a week after oviposition at our study site. Peaks in nest depredation (weeks with ≥10% nest depredation) occurred late in incubation and may have coincided with hatching. Trail cameras deployed at four nesting sites revealed six predator species interacting with nests. The presence of predators at nest sites increased late in the incubation period indicating a persistence or renewal (from hatching) of cues; additional research is necessary to determine the nature of these cues. These findings have implications for both research and turtle conservation. Further research should examine the relationship between temporal changes in predator species’ density and patterns of nest depredation. Additionally, in areas where protective nest caging is used as a species recovery action, it may be important to ensure that cages remain in place throughout the incubation period until emergence of hatchlings.

Natural history of the black-chested spiny-tailed iguanas,Ctenosaura melanosterna(Iguanidae), on Cayo Cochnino Menor, Honduras

We examined aspects of natural history and ecology of the black-chested spiny-tailed iguana, Ctenosaura melanosterna, on Cayo Cochino Menor, Honduras, over 6 years to provide baseline data to assist in management of this critically endangered species. Size of territory is resource-dependent, and the species seems to prefer habitats with open canopy. Mating occurred between March and June, with emergence of hatchlings from June to August. Ctenosaura melanosterna is an omnivore that feeds on a variety of vegetation, invertebrates, vertebrates, and food-scraps. The threats to this population include predation by Boa constrictor, competition with an increasing population of Iguana iguana, and potential poaching of adults and eggs for food.

A 21-Year Study of Seasonal and Interspecific Variation of Hatchling Emergence in a Nearctic Freshwater Turtle Community: To Overwinter or Not To Overwinter?

Abstract: Hatchling emergence patterns were studied in a community of six species of freshwater turtles in Lancaster County, Pennsylvania, USA, including: Chelydra serpentina, Chrysemys picta, Clemmys guttata, Glyptemys insculpta, Glyptemys muhlenbergii, and Sternotherus odoratus. Data were collected every year from 1965–1985 on estimated date of emergence, carapace length, April–May precipitation, August–September precipitation, annual precipitation, and low temperature and occurrence of precipitation during the 24 h prior to the time of each hatchling detection (n = 806). Chelydra serpentina, Ch. picta, and Cl. guttata hatchlings have a facultative delayed emergence strategy. The other species (G. insculpta, G. muhlenbergii, and S. odoratus) appear to be obligate early emergers, with the exception of one hatchling G. muhlenbergii that delayed emergence. Early emergence occurred in some species every year. However, the majority of hatchlings delayed emergence until the year following oviposition, excep...

Hatching and Emergence Patterns in the Yellow-Spotted River Turtle,Podocnemis unifilis(Testudines: Podocnemididae), in theVárzeaFloodplains of the Lower Amazon River in Santarém, Brazil

In reptiles, the hatching and emergence of a single clutch may be synchronized or may take place over a number of days, weeks, or even months, depending primarily on the microenvironment of the nest. The present study focused on the patterns of hatching and emergence of Podocnemis unifilis hatchlings in an area of várzea floodplain on the lower Amazon River in Santarém, in the Brazilian state of Pará, in 2007 and 2009. Two groups of nests were monitored for hatching and emergence, with the nests in one group being undisturbed during the entire study period. The difference between the oviposition–hatching and oviposition–emergence intervals was determined based on the monitoring of these processes in the monitored clutches. Hatchlings took 1.5 d to leave the eggshell and the eggs at the top of the nest hatched first. The size of the clutch influenced the length of the interval between the first and last hatching. Most hatchlings emerged from a nest during a single night. Hatchlings in late nests and those closer to vegetation took significantly longer to emerge. The hatching–emergence interval was greater in 2007 (11.0 d) than in 2009 (7.3 d). This study contributes to the understanding of hatching and emergence patterns in P. unifilis and the physical and environmental factors that influence them, including the variation between reproductive seasons.

Estrutura do ninho, incubação e eclosão de Phyllomedusa trinitatis (Anura: Hylidae)

New findings on nesting and hatching are reported for the leaf-nesting tree frog Phyllomedusa trinitatis. Nest height and leaf cover (one or many leaves; well or poorly covered) were very variable. Contrary to a previous report, eggless jelly capsules were scattered amongst the eggs, with substantial jelly plugs located above and below the egg clutch. Plugs were composed of capsules embedded in a matrix of somewhat different composition. The upper plug acted as a barrier to water entry. Contrary to previous reports, isolated eggs could develop in aquatic media, the later stage on entry the better: aeration and salt composition of the water influenced this ability. Egg clutches developed equally well whether the covering leaves were alive or dead. Single eggs incubated in water hatched prematurely; when placed in water, eggs near hatching stage hatched within a short time; such eggs on a dry or damp substrate did not hatch till much later. The hatching of any embryo in a group appeared to act as a stimulus to neighbours to hatch. Observations on nests with the covering leaves replaced by clingfilm showed that emergence is preceded by a lengthy period of hatching behavior, with individuals hatching, wriggling and stimulating larger and larger groups to hatch, and releasing a frothy fluid which leads to the dissolution of the lower jelly plug and emergence of the hatchlings. Contrary to a previous report, hatching gland cells were observable on the laterodorsal surface of the head. When hatchlings emerged from the nest, they were mostly at Gosner stage 25 with gills fully resorbed. When earlier embryos were induced to hatch, they rapidly shortened their external gills. These findings are discussed in comparison with observations on the related genus Agalychnis.

Reproductive Biology of the Loggerhead Sea Turtle, Caretta Caretta, in Dalyan Beach, Turkey, 2009

The reproductive biology of loggerhead turtles, Caretta caretta, was studied at Dalyan, Turkey in 2009. This study was conducted between 18 June and 15 September 2009. During the breeding season, the night and morning patrols on the beach were performed. During night patrols, they were tagged and after that body measurements were taken. During morning patrols, the shape and pattern of tracks were noted and those tracks that resulted in nests were marked. During the hatchling emergence season, the numbers of hatchling tracks coming from each nest were counted daily, and the numbers of hatchlings reaching the sea were determined by following the tracks. A total of 1154 emergences were recorded with 330 (29%) resulting in nests. Of these nests, 5% occurred in May, 57% in June, 36% in July and 2% in August. The nest density of C. caretta at Dalyan was 70.2 nests/km. The mean clutch size at Dalyan during 2009 breeding season was 68.3 eggs (range 25-138, n = 123). The incubation period was on average 50.2 days (range 40-63, n = 123). All eggs were predated in 177 nests (53%), and some eggs were predated in 51 nests (15%) by foxes (Vulpes vulpes) and badgers. A total of 102 nests (31%) were completely protected so that no eggs were predated. The hatching success was 31.9%. While 5398 hatchlings (85.3% of the total number of hatchlings) were able to reach the sea, 175 hatchlings (2.8%) died inside the nest, 695 (11%) were predated by foxes, and 59 (1%) were predated by crabs. Nests that were threatened by the tide or human activities were transplanted to safe areas of the beach. Furthermore, metal gratings were placed on the nests to prevent fox predation.

Australian Freshwater Crocodiles (Crocodylus johnstoni) Transport Their Hatchlings to the Water

Remote video cameras recorded eight instances of nest excavation and parental transport of offspring to the water by Australian freshwater crocodiles (Crocodylus johnstoni) inhabiting Lake Argyle in northwestern Australia. Parental assistance during hatching appears to be vital for successful emergence of hatchlings from nests in this area.

Climate Driven Egg and Hatchling Mortality Threatens Survival of Eastern Pacific Leatherback Turtles

Egg-burying reptiles need relatively stable temperature and humidity in the substrate surrounding their eggs for successful development and hatchling emergence. Here we show that egg and hatchling mortality of leatherback turtles (Dermochelys coriacea) in northwest Costa Rica were affected by climatic variability (precipitation and air temperature) driven by the El Niño Southern Oscillation (ENSO). Drier and warmer conditions associated with El Niño increased egg and hatchling mortality. The fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) projects a warming and drying in Central America and other regions of the World, under the SRES A2 development scenario. Using projections from an ensemble of global climate models contributed to the IPCC report, we project that egg and hatchling survival will rapidly decline in the region over the next 100 years by ∼50–60%, due to warming and drying in northwestern Costa Rica, threatening the survival of leatherback turtles. Warming and drying trends may also threaten the survival of sea turtles in other areas affected by similar climate changes.

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.

Nesting Ecology of a Population of Gopherus agassizii at a Utility-Scale Wind Energy Facility in Southern California

We investigated the annual nesting ecology of a population of Desert Tortoises (Gopherus agassizii) inhabiting a utility-scale renewable energy (USRE) facility in southern California and compared our results with populations inhabiting relatively undisturbed sites. In 2000, 15 radio-tracked females produced 29 clutches, and 24 nests were monitored to examine nest-site selection, nest predation, hatching success, date of emergence of hatchlings, and hatchling mass and carapace length. Overall, the nesting ecology of the population inhabiting the USRE facility was very similar to other populations of Desert Tortoises inhabiting relatively undisturbed habitats. Oviposition occurred from 12 May to 8 July, which was similar to other sites. Nest depths (11.1 cm), nest predation (12%), hatchling emergence date (7 August and 29 September), and hatchling morphometrics (i.e., MCL: 44.5 mm; mass: 23 g) were all within ranges reported in other populations. Unlike within other populations, we observed no relationship between hatchling size and either maternal body size or egg width. We found no evidence of females selecting for a particular burrow for oviposition of eggs based on environmental or anthropogenic variables. Most nests were located in or near burrows, and nest depth was greater for nests near the entrance than those deeper in the burrow. Although this study suggests that the nesting ecology of the Desert Tortoise population we studied was not adversely affected by the USRE facility, this relationship is only correlative because our study was not a before-after-control-impact (BACI) study, which would establish a cause and effect relationship. As pointed out in a recent review, BACI studies are critically needed to address the wildlife impacts of utility-scale renewable energy development.

Nesting, Hatching and Asynchronous Emergence of the Loggerhead Sea Turtle Caretta caretta at Isumi, Chiba, Central Honshu of Japan, during 2008-2010

The seacoast of Isumi City, Chiba Prefecture, Japan, is one of the northernmost nesting sites of loggerhead sea turtle Carettta caretta in the North Pacific. We observed nesting and hatching events of this species and investigated for asynchronous emergence of hatchlings from 2008 to 2010. In 2008, hatchlings emerged from all nests from July to September, but in 2009 and 2010, most clutches laid in August failed to hatch probably due to low ambient temperature resulting from low atmospheric temperature with insufficient sunshine. In one nest constructed in early July of 2010, hatchling emergence started in early September and completed in late September, 18 days after initial emergence. This extends the previous maximum records of duration of emergence from a single nest by 13 days.

EFFECTS OF FLOW DYNAMICS ON THE AQUATIC‐TERRESTRIAL TRANSITION ZONE (ATTZ) OF LOWER MISSOURI RIVER SANDBARS WITH IMPLICATIONS FOR SELECTED BIOTA

ABSTRACTSandbars are an important aquatic terrestrial transition zone (ATTZ) in the active channel of rivers that provide a variety of habitat conditions for riverine biota. Channelization and flow regulation in many large rivers have diminished sandbar habitats and their rehabilitation is a priority. We developed sandbar‐specific models of discharge‐area relationships to determine how changes in flow regime affect the area of different habitat types within the submerged sandbar ATTZ (depth) and exposed sandbar ATTZ (elevation) for a representative sample of Lower Missouri River sandbars. We defined six different structural habitat types within the sandbar ATTZ based on depth or exposed elevation ranges that are important to different biota during at least part of their annual cycle for either survival or reproduction. Scenarios included the modelled natural flow regime, current managed flow regime and two environmental flow options, all modelled within the contemporary river active channel. Thirteen point and wing‐dike sandbars were evaluated under four different flow scenarios to explore the effects of flow regime on seasonal habitat availability for foraging of migratory shorebirds and wading birds, nesting of softshell turtles and nursery of riverine fishes. Managed flows provided more foraging habitat for shorebirds and wading birds and more nursery habitat for riverine fishes within the channelized reach sandbar ATTZ than the natural flow regime or modelled environmental flows. Reduced summer flows occurring under natural and environmental flow alternatives increased exposed sandbar nesting habitat for softshell turtle hatchling emergence. Results reveal how management of channelized and flow regulated large rivers could benefit from a modelling framework that couples hydrologic and geomorphic characteristics to predict habitat conditions for a variety of biota. Published in 2011 by John Wiley & Sons, Ltd.

Nesting, Hatching and Asynchronous Emergence of the Loggerhead Sea Turtle Caretta caretta at Isumi, Chiba, Central Honshu of Japan, during 2008-2010

The seacoast of Isumi City, Chiba Prefecture, Japan, is one of the northernmost nesting sites of loggerhead sea turtle Carettta caretta in the North Pacific. We observed nesting and hatching events of this species and investigated for asynchronous emergence of hatchlings from 2008 to 2010. In 2008, hatchlings emerged from all nests from July to September, but in 2009 and 2010, most clutches laid in August failed to hatch probably due to low ambient temperature resulting from low atmospheric temperature with insufficient sunshine. In one nest constructed in early July of 2010, hatchling emergence started in early September and completed in late September, 18 days after initial emergence. This extends the previous maximum records of duration of emergence from a single nest by 13 days.

Winter severity and phenology of spring emergence from the nest in freshwater turtles

Although many species of freshwater turtles emigrate to water soon after hatching, the offspring of some species overwinter on land and move to aquatic habitats in the following spring. Timing of emigration can affect the hatchlings' fitness, but the factors underlying phenology of nest emergence are incompletely understood. We tested the supposition that cold stress imposed during hibernation can influence the timing of nest emergence in three species of turtles in the central USA. In each year of the 6-year study, Chrysemys picta emerged in late March and early April and, on average, these hatchlings left their nests 2 weeks earlier than those of Graptemys geographica and 4 weeks earlier than those of Trachemys scripta. Emergence of conspecific hatchlings from different nests usually occurred over 3-7 weeks, but in some years lasted several additional weeks. Relatively few nests had siblings that emerged on the same day (i.e., synchronously); complete emergence of the typical sibling group required 1 to 2 weeks. In winter, subzero cold occurred with regularity in the nests of all species, though C. picta experienced the lowest temperatures owing to their shallower nests. However, for no species did emergence date or length of the emergence period correlate with winter minimum temperature and, at the level of the individual nest, neither did emergence synchrony or duration. Despite encountering lower temperatures, hatchlings of C. picta emigrated from their nests before those of sympatric species, suggesting that the fitness benefits of early emergence may lead to the improvement of cold-hardiness adaptations in northern populations of turtles.

Mycoflora identified from loggerhead turtle (Caretta caretta) egg shells and nest sand at Fethiye beach, Turkey

The aim of this study was to investigate the mycoflora of the loggerhead turtle,Caretta caretta, from its nests and eggshells at Fethiye beach, Turkey. During the 2004 breeding season, following the complete emergence of the hatchlings, sand samples were collected from 15 nests and eggs from these nests were swabbed. Rose Bengal chloramphenicol agar was used for isolation, and then mycoflora were subcultured onto suitable media. Fungi were counted and identified at genus level. Ten genera were identified within the nests and eggshells. Aspergillus sp.,Chrysosporium sp., Fusarium sp. and Penicillum sp. were identified both in nests and eggshells. Furthermore, while Absidia sp., Cylindrocarpon sp., Emericella sp. and Mucor sp. were only identified in the nests, Cladosporium sp. and Thielavia sp. were only identified in eggshells. In addition, there was a positive correlation between total number of isolated fungus and embryonic death in nests (r = 0.53, p < 0.05). Hatching success was negatively correlated with total number of isolated fungus (r = -0.54, p < 0.05). Our study indicates a relation between hatching success and fungal flora of the nests. Presence of fungi may also be important for the researchers who digs nest to avoid infections or allergies due to these fungi. Key words: Mycoflora, fungus, Caretta caretta, Fethiye beach.

Los huevos falsos (SAGs) facilitan el comportamiento social de emergencia en las crías de la tortuga laúd Dermochelys coriacea (Testudines: Dermochelyidae)

Hatchling emergence to the beach surface from deep sand nests occurs without parental care. Social behaviour among siblings is crucial to overcome this first challenge in sea turtles life. This study, carried out at the Caribbean coast of Colombia, describes the emergence social behaviour of hatchlings from eight nests, and assess the nests translocation effects on temporal patterns of emergence. For the first time, we propose that space released by dehydration of shelled albumen globes (SAGs) at the top of the clutch, might be a reproductive advantage, while facilitating neonates to group together in a very limited space, and favouring the synchrony of emergence. The mean time of groups emergence was of 3.3 days, varying between 1 and 6 days. We found that relocation of the nests did not significantly affect the temporal pattern of emergence, which was mainly nocturnal (77.7% of natural nests and 81.7% of translocated ones). The maximum number of emergences to the surface occurred at the lowest air temperatures (22:00h-06:00h). The selective advantage of this pattern is probably related to the greater rate of predation and mortality by hyperthermia observed during the day.