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Debra L. Miller - One of the best experts on this subject based on the ideXlab platform.
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Nesting leatherback sea turtle dermochelys coriacea packed cell volumes indicate decreased foraging during reproduction
Marine Biology, 2016Co-Authors: Annie Pagekarjian, Justin R. Perrault, Debra L. MillerAbstract:Leatherback sea turtles (Dermochelys coriacea) are hypothesized to be capital breeders, whereby they forage little to none during the Nesting Season. The capital breeding hypothesis can be tested in marine turtles using physiological measures of health, which are much less expensive than studies that use satellite tags or other physiological monitoring equipment to make inferences about behavior and foraging status during the Nesting Season. In this study, we analyzed packed cell volumes (PCVs), a simple and inexpensive, hematologic health parameter, in Nesting leatherback turtles from St. Croix, U.S. Virgin Islands (17°40′40″N, 64°54′0″W) across the Nesting Season (April–July 2009) in an effort to determine foraging status. We found that PCV in Nesting females significantly declined using two longitudinal measures: nest number and level of reproductive effort. We also found that PCVs of remigrants were significantly higher in comparison with neophytes, suggesting that experience in reproductive activities (e.g., migration, breeding, Nesting) might increase foraging success on feeding grounds. Lastly, we found that leatherbacks with a greater reproductive output had significantly higher PCVs. While the northwest Atlantic leatherback population is evaluated as least concern by the IUCN, Pacific leatherbacks are critically endangered. The assumed behaviors of turtles from this study provide insight into reproductive strategies and energy reserves in all marine turtle populations. Thus, the results presented here are applicable to (1) veterinarians, rehabilitation facilities, and conservationists and (2) other more vulnerable marine turtle populations.
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Seasonal trends in Nesting leatherback turtle dermochelys coriacea serum proteins further verify capital breeding hypothesis
Conservation Physiology, 2014Co-Authors: Justin R. Perrault, Annie Pagekarjian, Jeanette Wyneken, Anita Merrill, Debra L. MillerAbstract:Serum protein concentrations provide insight into the nutritional and immune status of organisms. It has been suggested that some marine turtles are capital breeders that fast during the Nesting Season. In this study, we documented serum proteins in neophyte and remigrant Nesting leatherback sea turtles (Dermochelys coriacea). This allowed us to establish trends across the Nesting Season to determine whether these physiological parameters indicate if leatherbacks forage or fast while on Nesting grounds. Using the biuret method and agarose gel electrophoresis, total serum protein (median = 5.0 g/dl) and pr otein fractions were quantified and include pre-albumin (median = 0.0 g/dl), albumin (median = 1.81 g/dl), α1-globulin (median = 0.90 g/dl), α2-globulin (median = 0.74 g/dl), total α-globulin (median = 1.64 g/dl), β-globulin (median = 0.56 g/dl), γ-globulin (median = 0.81 g/dl) and total globulin (median = 3.12 g/dl). The albumin:globulin ratio (median = 0.59) was also calculated. Confidence intervals (90%) were used to establish reference intervals. Total protein, albumin and total globulin concentrations declined in successive Nesting events. Protein fractions declined at less significant rates or remained relatively constant during the Nesting Season. Here, we show that leatherbacks are most likely fasting during the Nesting Season. A minimal threshold of total serum protein concentrations of around 3.5–4.5 g/dl ma y physiologically signal the end of the Season’s Nesting for individual leatherbacks. The results presented here lend further insight into the interaction between reproduction, fasting and energy reserves and will potentially improve the conservation and management of this imperiled species.
Price Melissa - One of the best experts on this subject based on the ideXlab platform.
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Seasonal patterns in nest survival of a subtropical wading bird, the Hawaiian Stilt (Himantopus mexicanus knudseni)
'PeerJ', 2021Co-Authors: Harmon Kristen, Wehr Nathaniel, Price MelissaAbstract:Nest survival is influenced by where and when birds decide to breed. For ground-Nesting species, nest-site characteristics, such as vegetation height and proximity to water, may impact the likelihood of nest flooding or depredation. Further, habitat characteristics, and thus nest survival, may fluctuate across the breeding Season. The Hawaiian Stilt (‘Ae‘o; Himantopus mexicanus knudseni) is an endangered Hawaiian waterbird that nests in wetlands across the Hawaiian Islands. In this study, we used observational surveys and nest cameras to examine the impact of nest-site characteristics and day of Nesting Season on nest survival of the Hawaiian Stilt. Early nests had a higher chance of survival than late nests. For most of the Nesting Season, taller vegetation was correlated with increased nest survival, while shorter vegetation was correlated with increased nest survival late in the Nesting Season. Seasonal patterns in nest survival may be due to changes in parental behavior or predator activity. Nest depredation was responsible for 55% of confirmed nest failures and introduced mammals were the primary nest predators. Our study is the first to examine Seasonality in nest survival of Hawaiian Stilts and suggests that, despite longer Nesting Seasons and year-round occupation of wetlands, late nesters in subtropical regions may have lower nest survival than early nesters, similar to trends observed in temperate regions
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Nest depredation risk increases later in the Nesting Season for a subtropical wading bird, the Hawaiian Stilt (Himantopus mexicanus knudseni)
2020Co-Authors: Harmon Kristen, Wehr Nathaniel, Price MelissaAbstract:Nest depredation is the leading cause of nest failure in avian species. While depredation risk largely depends on depredation pressure, it may also be influenced by the timing of the Nesting Season and by nest site features, such as proximity to water and vegetation height. The Hawaiian Stilt (Himantopus mexicanus knudseni) is an endangered Hawaiian waterbird that nests in wetlands across the Hawaiian Islands from February to September. The Nesting Season coincides with a Seasonal decline in precipitation, which may impact depredation rates. In this study, we used observational surveys and nest cameras to examine the impact of nest-site characteristics and nest initiation date on nest depredation of the Hawaiian Stilt. We found that stilts preferred shorter vegetation than what was randomly available and preferred to nest in Pickleweed (Batis maritima) rather than other available plant species. However, nest-site characteristics, such as vegetation height and distance to water, did not have an impact on depredation risk. Early nests had a higher chance of survival than late nests. The number of depredated nests peaked later in the Nesting Season, and introduced mammals were the primary nest predators. Increasing invasive predator control later in the Hawaiian Stilt Nesting Season, particularly for mammalian predators, may increase nest survival of later nesters. Our study is the first to examine Seasonality in nest depredation of Hawaiian Stilts and suggests that, despite longer Nesting Seasons and year-round occupation of wetlands, late nesters in subtropical regions may have greater depredation risk than early nesters, similar to trends observed in temperate regions
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Nesting Ecology of the Hawaiian Stilt (Himantopus mexicanus knudseni) on O‘ahu
2020Co-Authors: Price Melissa, Harmon Kristen, Idle Jessica, Christensen Dain, Opie ErynAbstract:The Hawaiian Stilt (Himantopus mexicanus knudseni) is an endangered subspecies of the Black-necked stilt (Himantopus mexicanus) that inhabits wetlands throughout the Hawaiian Islands. Depredation of eggs and chicks by introduced predators is a major threat to Hawaiian Stilt populations. Where and when a bird decides to nest may impact the likelihood of egg or chick depredation. Nesting in close proximity to water may decrease depredation rates by mammals, as water can act as a barrier to mammalian predators, does not hold scent, and provides an obstacle-free escape route for chicks. Alternatively, some mammalian predators may be attracted to water, and a number of aquatic species have been identified as predators of Hawaiian Stilt chicks, including the American Bullfrog (Lithobates catesbeianus). Vegetation height is also an important factor for egg and chick survival, as taller vegetation may help conceal nests and chicks from predators, particularly aerial species. Additionally, depredation is often not constant across the breeding Season due to changes in parental activity, nest and chick abundance, or habitat characteristics. The Hawaiian Stilt nests from February to September across the Hawaiian Islands. The Nesting Season coincides with a Seasonal decline in precipitation, which may alter habitat characteristics and thus impact depredation rates. Further, management tools, such as mammal-exclusion fencing, are currently in use and may greatly increase egg and chick survival. The objectives of this project were to: 1) identify habitat characteristics important for nest-site selection and chick habitat use; 2) identify factors that impact hatching and fledging success. We found that stilts preferred to nest in shorter vegetation than what was available and preferred Pickleweed (Batis maritima) rather than other available plant species. However, nest-site characteristics, such as vegetation height and distance to water, did not have an impact on egg depredation risk. Early nests had a higher chance of hatching than late nests. The number of depredated nests peaked later in the Nesting Season, following a peak in nest initiation. Introduced mammals were the primary egg predators and included rats (Rattus spp.), feral cats (Felis catus), and Small Indian Mongooses (Herpestes auropunctatus). The number of eggs laid, as well as hatching success, was greater inside the mammal exclusion fence at Honouliuli Wetland, compared to a nearby site without a fence, Waiawa Wetland, where mammalian predators are only excluded via trapping. The average home range size for 12 tracked pre-fledglings was 0.94 ± 1.42 acres, and most chicks were observed using vegetated mudflats near open water. Of the 20 chicks that were tracked in this study, 7 fledged (35%), 6 had unknown fates (30%), 4 died due to unknown causes (20%), 2 were depredated by a feral cat (10%), and 1 died due to emaciation (5%). Our results suggest that management of predators, particularly mammals, is key to improving stilt hatching success, as preferred nest-site characteristics do not reduce the likelihood of egg depredation. Tall, invasive vegetation, such as California Grass (Brachiaria mutica), should continue to be controlled, as it was rarely used for Nesting. More desirable vegetation, such as Pickleweed, should be made available throughout wetlands to encourage larger spacing between Nesting pairs, which may help to reduce egg depredation pressure. Increasing mammalian predator control later in the Nesting Season may also increase hatching success of later nesters. Alternatively, mammal-exclusion fencing may provide year-round protection from mammalian predators, increasing both egg and chick survival. More data is needed to form conclusions regarding home range and survival of Hawaiian Stilt chicks. Improved detection methods and radio-tagging attachment styles will be used in the 2020 Nesting Season, which will reduce uncertainties and improve statistical power of analyses
Richard D Reina - One of the best experts on this subject based on the ideXlab platform.
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Comparison of UAV and Boat Surveys for Detecting Changes in Breeding Population Dynamics of Sea Turtles
'MDPI AG', 2021Co-Authors: Adam Yaney-keller, Ricardo San Martin, Richard D ReinaAbstract:Surveying the breeding population of a given species can be difficult for many logistic reasons. Marine turtles are a challenging taxon for the study of reproductive ecology and breeding strategies, because turtles aggregate off-shore and males remain exclusively at sea. For successful management of sea turtle populations, determining operational sex ratios (OSRs) on a continuing basis is critical for determining long-term population viability, particularly in the context of changing hatchling sex ratios due to temperature-dependent sex determination in a warming climate. To understand how survey technique and stage of the breeding Season might influence the ability to detect turtles and determine OSRs, we surveyed the presence and identified the sex of adult male and female green sea turtles (Chelonia mydas) using a boat and small commercial unoccupied/unmanned aerial vehicle (UAV), at the start (October) and peak (December) of a Nesting Season at an important breeding site at Heron Island, Great Barrier Reef, Australia. The ratio of males to females within the breeding ground detected by both survey methods changed from being male-biased in October to heavily female-biased in December, indicating that most males cease their reproductive effort and depart before the peak of the Nesting Season. Surveying with a UAV more than doubled the rate of turtles seen per minute of survey effort compared with surveying solely from the boat and allowed surveys to be conducted at times and/or places unsafe or inaccessible for boats. The sex of a slightly greater proportion of turtles seen could not be identified by observers using a UAV versus a boat, although more turtles were detected using the UAV. The departure of many males during the peak of the Nesting Season is likely due to an increasing biological cost of residency in the area because males encounter fewer receptive females as the Season progresses and the limited foraging opportunity is insufficient to support the number of males present. Overall, we found that UAVs are an effective tool for studying important but difficult to observe aspects of sea turtle biology
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embryonic death is linked to maternal identity in the leatherback turtle dermochelys coriacea
PLOS ONE, 2011Co-Authors: Anthony R Rafferty, Frank V Paladino, James R. Spotila, Pilar Santidrian Tomillo, Richard D ReinaAbstract:Leatherback turtles have an average global hatching success rate of ∼50%, lower than other marine turtle species. Embryonic death has been linked to environmental factors such as precipitation and temperature, although, there is still a lot of variability that remains to be explained. We examined how Nesting Season, the time of Nesting each Season, the relative position of each clutch laid by each female each Season, maternal identity and associated factors such as reproductive experience of the female (new nester versus remigrant) and period of egg retention between clutches (interclutch interval) affected hatching success and stage of embryonic death in failed eggs of leatherback turtles Nesting at Playa Grande, Costa Rica. Data were collected during five Nesting Seasons from 2004/05 to 2008/09. Mean hatching success was 50.4%. Nesting Season significantly influenced hatching success in addition to early and late stage embryonic death. Neither clutch position nor Nesting time during the Season had a significant affect on hatching success or the stage of embryonic death. Some leatherback females consistently produced nests with higher hatching success rates than others. Remigrant females arrived earlier to nest, produced more clutches and had higher rates of hatching success than new nesters. Reproductive experience did not affect stage of death or the duration of the interclutch interval. The length of interclutch interval had a significant affect on the proportion of eggs that failed in each clutch and the developmental stage they died at. Intrinsic factors such as maternal identity are playing a role in affecting embryonic death in the leatherback turtle.
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low reproductive success of leatherback turtles dermochelys coriacea is due to high embryonic mortality
Biological Conservation, 2004Co-Authors: Barbara Bell, James R. Spotila, Frank V Paladino, Richard D ReinaAbstract:We examined the mechanism responsible for low reproductive success in leatherback turtles (Dermochelys coriacea) at Playa Grande, Costa Rica: low egg fertilization versus high rates of embryonic death. Leatherbacks at this beach had a high rate of fertility (X=93.3%� 2.5%, n=819). We incubated 10 eggs from every clutch encountered of 19 females during 3 months of the 1998– 1999 Nesting Season. Fertility rate of some females decreased during the Nesting Season, but overall was high. Detection of fertility was difficult using standard methods because fertility rates cannot be determined accurately from nests excavated after hatching because of egg decomposition. Removal and incubation of eggs from nests provided a better estimate. Embryonic death, particularly in the beginning of incubation before embryos are visible to the unaided eye, was the cause of low hatching success in this population. Hatching success increased with increasing fertility and differed between females, with some mothers having 71–81% success and others 23–32%. Embryonic death and not low egg fertility drives poor recruitment at Playa Grande. Improved conservation of this species at Playa Grande will require a better understanding of the mechanism behind embryonic death. # 2003 Elsevier Ltd. All rights reserved.
Marc Girondot - One of the best experts on this subject based on the ideXlab platform.
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Nesting estimation and analysis of threats for critically endangered leatherback dermochelys coriacea and endangered olive ridley lepidochelys olivacea marine turtles Nesting in congo
Oryx, 2009Co-Authors: Marieclelia Godgenger, Nathalie Breheret, Karine Ndamite, Alexandre Girard, Marc GirondotAbstract:Six marine turtle species are reported from the coastal waters of the Republic of the Congo. Among them, Nesting by the Critically Endangered leatherback Dermochelys coriacea and Endangered olive ridley Lepidochelys olivacea marine turtles occurs annually from September to April on Congolese beaches. We developed a methodology to model the Nesting Season of marine turtles and apply it to the time series of nest counts for six Nesting beaches monitored over 2–4 years. There is a peak of Nesting activity in early January for leatherback turtles and early December for olive ridley turtles. We show a decline of olive ridley nests during this period whereas leatherback Nesting increased, and propose that differential threats for these two species explain such a contrasted pattern.
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maternal transfer of trace elements in leatherback turtles dermochelys coriacea of french guiana
Aquatic Toxicology, 2008Co-Authors: Elodie Guirlet, Marc GirondotAbstract:In sea turtles, parental investment is limited to the nutrients and energy invested in eggs that will support embryonic development. Leatherback females have the largest clutches with the biggest eggs of the sea turtles and the highest reproductive output in reptiles. The migration between foraging sites and Nesting beaches also represents high energy expenditure. The toxicokinetic of pollutants in the tissues is thus expected to vary during those periods but there is a lack of information in reptiles. Concentrations of essential (Copper, Zinc, Selenium) and non-essentials elements (Cadmium, Lead, Mercury) were determined in blood (n = 78) and eggs (n = 76) of 46 free-ranging leatherback females collected in French Guiana. Maternal transfer to eggs and relationships between blood and eggs concentrations during the Nesting Season were investigated. All trace elements were detectable in both tissues. Levels of toxic metals were lower than essential elements likely due to the high pelagic nature of leatherbacks that seems to limit exposure to toxic elements. Significant relationships between blood and egg concentrations were observed for Se and Cd. Se could have an important role in embryonic development of leatherback turtles and Cd transfer could be linked to similar carrier proteins as Se. Finally, as multiple clutches were sampled from each female, trends in trace elements were investigated along the Nesting Season. No change was observed in eggs but changes were recorded in blood concentrations of Cu. Cu level decreased while blood Pb levels increased through the Nesting Season. The high demand on the body during the breeding Season seems to affect blood Cu concentrations. Calcium requirement for egg production with concomitant Pb mobilization could explain the increase in blood Pb concentrations along the Nesting Season.
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Trade-off between current reproductive effort and delay to next reproduction in the leatherback sea turtle
Oecologia, 2005Co-Authors: Philippe Rivalan, Anne-caroline Prevot-julliard, Rémi Choquet, Roger Pradel, Bertrand Jacquemin, Marc GirondotAbstract:The trade-off between current and future reproduction plays an important role in demographic analyses. This can be revealed by the relationship between the number of years without reproduction and reproductive investment within a reproductive year. However, estimating both the duration between two successive breeding Season and reproductive effort is often limited by variable recapture or resighting effort. Moreover, a supplementary difficulty is raised when nonbreeder individuals are not present sampling breeding grounds, and are therefore unobservable. We used capture-recapture (CR) models to investigate intermittent breeding and reproductive effort to test a putative physiological trade-off in a long-lived species with intermittent breeding, the leatherback sea turtle. We used CR data collected on breeding females on Awa:la-Ya:lima:po beach (French Guiana, South America) from 1995 to 2002. By adding specific constraints in multistate (MS) CR models incorporating several non-observable states, we modelled the breeding cycle in leatherbacks and then estimated the reproductive effort according to the number of years elapsed since the last Nesting Season. Using this MS CR framework, the mean survival rate was estimated to 0.91 and the average resighting probability to 0.58 (ranged from 0.30 to 0.99). The breeding cycle was found to be limited to 3 years. These results therefore suggested that animals whose observed breeding intervals are greater than 3 years were most likely animals that escaped detection during their previous Nesting Season(s). CR data collected in 2001 and 2002 allowed us to compare the individual reproductive effort between females that skipped one breeding Season and females that skipped two breeding Seasons. These inferences led us to conclude that a trade-off between current and future reproduction exists in leatherbacks Nesting in French Guiana, likely linked to the resource provisioning required to invest in reproduction .
Justin R. Perrault - One of the best experts on this subject based on the ideXlab platform.
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Nesting leatherback sea turtle dermochelys coriacea packed cell volumes indicate decreased foraging during reproduction
Marine Biology, 2016Co-Authors: Annie Pagekarjian, Justin R. Perrault, Debra L. MillerAbstract:Leatherback sea turtles (Dermochelys coriacea) are hypothesized to be capital breeders, whereby they forage little to none during the Nesting Season. The capital breeding hypothesis can be tested in marine turtles using physiological measures of health, which are much less expensive than studies that use satellite tags or other physiological monitoring equipment to make inferences about behavior and foraging status during the Nesting Season. In this study, we analyzed packed cell volumes (PCVs), a simple and inexpensive, hematologic health parameter, in Nesting leatherback turtles from St. Croix, U.S. Virgin Islands (17°40′40″N, 64°54′0″W) across the Nesting Season (April–July 2009) in an effort to determine foraging status. We found that PCV in Nesting females significantly declined using two longitudinal measures: nest number and level of reproductive effort. We also found that PCVs of remigrants were significantly higher in comparison with neophytes, suggesting that experience in reproductive activities (e.g., migration, breeding, Nesting) might increase foraging success on feeding grounds. Lastly, we found that leatherbacks with a greater reproductive output had significantly higher PCVs. While the northwest Atlantic leatherback population is evaluated as least concern by the IUCN, Pacific leatherbacks are critically endangered. The assumed behaviors of turtles from this study provide insight into reproductive strategies and energy reserves in all marine turtle populations. Thus, the results presented here are applicable to (1) veterinarians, rehabilitation facilities, and conservationists and (2) other more vulnerable marine turtle populations.
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Seasonal trends in Nesting leatherback turtle dermochelys coriacea serum proteins further verify capital breeding hypothesis
Conservation Physiology, 2014Co-Authors: Justin R. Perrault, Annie Pagekarjian, Jeanette Wyneken, Anita Merrill, Debra L. MillerAbstract:Serum protein concentrations provide insight into the nutritional and immune status of organisms. It has been suggested that some marine turtles are capital breeders that fast during the Nesting Season. In this study, we documented serum proteins in neophyte and remigrant Nesting leatherback sea turtles (Dermochelys coriacea). This allowed us to establish trends across the Nesting Season to determine whether these physiological parameters indicate if leatherbacks forage or fast while on Nesting grounds. Using the biuret method and agarose gel electrophoresis, total serum protein (median = 5.0 g/dl) and pr otein fractions were quantified and include pre-albumin (median = 0.0 g/dl), albumin (median = 1.81 g/dl), α1-globulin (median = 0.90 g/dl), α2-globulin (median = 0.74 g/dl), total α-globulin (median = 1.64 g/dl), β-globulin (median = 0.56 g/dl), γ-globulin (median = 0.81 g/dl) and total globulin (median = 3.12 g/dl). The albumin:globulin ratio (median = 0.59) was also calculated. Confidence intervals (90%) were used to establish reference intervals. Total protein, albumin and total globulin concentrations declined in successive Nesting events. Protein fractions declined at less significant rates or remained relatively constant during the Nesting Season. Here, we show that leatherbacks are most likely fasting during the Nesting Season. A minimal threshold of total serum protein concentrations of around 3.5–4.5 g/dl ma y physiologically signal the end of the Season’s Nesting for individual leatherbacks. The results presented here lend further insight into the interaction between reproduction, fasting and energy reserves and will potentially improve the conservation and management of this imperiled species.
