A. Zavala-Norzagaray, C. Ley-Quiñónez, C. E. Hart, Paula Aguilar-Claussell, S. H. Peckham, A. A. Aguirre
Abstract Loggerhead turtles (Caretta caretta) are characterized by their transoceanic migratory patterns in the North Pacific Ocean, as individuals of this species originating from nesting beaches in Japan are known to forage along the Baja California Peninsula (BCP), Mexico. The nearshore waters of BCP serve as important foraging habitat for growth and development; however, the implementation of appropriate management strategies has been hindered by the paucity of data on the biology and distribution of the species, particularly for juveniles during their developmental migrations. We report for the first time the occurrence and distribution of loggerhead turtles in Sinaloa, Mexico, in the southernmost portion of the Gulf of California.
{"title":"First Record of Loggerhead Sea Turtles (Caretta caretta) in the Southern Gulf of California, Sinaloa, Mexico","authors":"A. Zavala-Norzagaray, C. Ley-Quiñónez, C. E. Hart, Paula Aguilar-Claussell, S. H. Peckham, A. A. Aguirre","doi":"10.2744/CCB-1238.1","DOIUrl":"https://doi.org/10.2744/CCB-1238.1","url":null,"abstract":"Abstract Loggerhead turtles (Caretta caretta) are characterized by their transoceanic migratory patterns in the North Pacific Ocean, as individuals of this species originating from nesting beaches in Japan are known to forage along the Baja California Peninsula (BCP), Mexico. The nearshore waters of BCP serve as important foraging habitat for growth and development; however, the implementation of appropriate management strategies has been hindered by the paucity of data on the biology and distribution of the species, particularly for juveniles during their developmental migrations. We report for the first time the occurrence and distribution of loggerhead turtles in Sinaloa, Mexico, in the southernmost portion of the Gulf of California.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1238.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41286146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Foraging behavior from 30 wild hawksbill turtles (Eretmochelys imbricata) was video-recorded by scuba divers on the coral reefs of Palm Beach County, Florida. A transition matrix was created to calculate the sequence and frequency of 5 behavioral categories leading to prey ingestion, and general observations associated with foraging behavior were described. Likely aided by olfaction, the hawksbills at this site employed a multistep process to preferentially locate and ingest well-concealed sessile invertebrates, notably poriferans of the class Demospongiae. Cumulatively, behavioral frequencies decreased as the sequence progressed toward prey consumption, and only a small proportion of the items handled were ingested. Highly exploratory foraging behavior may aid hawksbills to adaptively identify and prioritize dietary preferences within and among habitat types.
{"title":"Foraging Behavior of Wild Hawksbill Turtles (Eretmochelys imbricata) in Palm Beach County, Florida, USA","authors":"Lawrence D. Wood, S. Milton, T. Maple","doi":"10.2744/CCB-1242.1","DOIUrl":"https://doi.org/10.2744/CCB-1242.1","url":null,"abstract":"Abstract Foraging behavior from 30 wild hawksbill turtles (Eretmochelys imbricata) was video-recorded by scuba divers on the coral reefs of Palm Beach County, Florida. A transition matrix was created to calculate the sequence and frequency of 5 behavioral categories leading to prey ingestion, and general observations associated with foraging behavior were described. Likely aided by olfaction, the hawksbills at this site employed a multistep process to preferentially locate and ingest well-concealed sessile invertebrates, notably poriferans of the class Demospongiae. Cumulatively, behavioral frequencies decreased as the sequence progressed toward prey consumption, and only a small proportion of the items handled were ingested. Highly exploratory foraging behavior may aid hawksbills to adaptively identify and prioritize dietary preferences within and among habitat types.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1242.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43917222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Managers making decisions may benefit from a well-informed understanding of a species' population size and trends. Given the cryptic nature and habitat characteristics of the western pond turtle (Emys marmorata), however, imperfect detection may be high and population estimates are frequently varied and unreliable. As a case study to investigate this issue, we used temperature dataloggers to examine turtle behavior at 2 long-term monitoring sites with different hydrological characteristics in Sequoia National Park, California, to determine if common stream-survey techniques are consistent with site-specific turtle behavior. Sycamore Creek is an intermittent stream that dries up every summer while the North Fork Kaweah River flows year-round. We found that while turtles spent most of the recorded time in the water (55% in Sycamore Creek and 82% in the North Fork Kaweah River), the timing of traditional surveys only coincided with the turtles' aquatic activity in the North Fork Kaweah River. At Sycamore Creek, turtles were most likely to be in the water at night. In contrast, failure to detect turtles in North Fork Kaweah River is likely owing to the larger size and complexity of the underwater habitat. In both streams, turtles were also more likely to be in the water in the weeks leading up to important changes in hydroperiods. Our findings illustrate the effects that differences in water permanence can have on turtle behavior within the same watershed and how phenotypic plasticity may then affect detection during surveys. Our study highlights the importance of tailoring survey practices to the site-specific behavioral traits of the target species.
{"title":"Seasonal and Diel Environmental Conditions Predict Western Pond Turtle (Emys marmorata) Behavior at a Perennial and an Ephemeral Stream in Sequoia National Park, California","authors":"Gabrielle E Ruso, Erik Meyer, Adrian J. Das","doi":"10.2744/CCB-1240.1","DOIUrl":"https://doi.org/10.2744/CCB-1240.1","url":null,"abstract":"Abstract Managers making decisions may benefit from a well-informed understanding of a species' population size and trends. Given the cryptic nature and habitat characteristics of the western pond turtle (Emys marmorata), however, imperfect detection may be high and population estimates are frequently varied and unreliable. As a case study to investigate this issue, we used temperature dataloggers to examine turtle behavior at 2 long-term monitoring sites with different hydrological characteristics in Sequoia National Park, California, to determine if common stream-survey techniques are consistent with site-specific turtle behavior. Sycamore Creek is an intermittent stream that dries up every summer while the North Fork Kaweah River flows year-round. We found that while turtles spent most of the recorded time in the water (55% in Sycamore Creek and 82% in the North Fork Kaweah River), the timing of traditional surveys only coincided with the turtles' aquatic activity in the North Fork Kaweah River. At Sycamore Creek, turtles were most likely to be in the water at night. In contrast, failure to detect turtles in North Fork Kaweah River is likely owing to the larger size and complexity of the underwater habitat. In both streams, turtles were also more likely to be in the water in the weeks leading up to important changes in hydroperiods. Our findings illustrate the effects that differences in water permanence can have on turtle behavior within the same watershed and how phenotypic plasticity may then affect detection during surveys. Our study highlights the importance of tailoring survey practices to the site-specific behavioral traits of the target species.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1240.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43820991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Broad variation in egg hatching success observed in gopher tortoise (Gopherus polyphemus) populations led us to investigate hatching success and other reproductive attributes within a unique, high-quality site in the eastern portion of the species' range. We documented use of a juvenile tortoise burrow as a nest site, a mean clutch size of 5.9 eggs, long oviposition-to-hatchling emergence times (96–128 d), and 73% hatching success for predator-protected eggs. Although consistent with previous reports of greater hatching success in eastern gopher tortoise populations than in western ones, hatching success at our eastern site was on the low end of values from other eastern populations, possibly reflecting above average rainfall during this study.
{"title":"Hatching Success and Other Reproductive Attributes of Gopher Tortoises in Southwest Georgia","authors":"T. Radzio, J. A. Cox, M. O’connor","doi":"10.2744/CCB-1166.1","DOIUrl":"https://doi.org/10.2744/CCB-1166.1","url":null,"abstract":"Abstract Broad variation in egg hatching success observed in gopher tortoise (Gopherus polyphemus) populations led us to investigate hatching success and other reproductive attributes within a unique, high-quality site in the eastern portion of the species' range. We documented use of a juvenile tortoise burrow as a nest site, a mean clutch size of 5.9 eggs, long oviposition-to-hatchling emergence times (96–128 d), and 73% hatching success for predator-protected eggs. Although consistent with previous reports of greater hatching success in eastern gopher tortoise populations than in western ones, hatching success at our eastern site was on the low end of values from other eastern populations, possibly reflecting above average rainfall during this study.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1166.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49481068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The nesting population of leatherback sea turtles at the Sandy Point National Wildlife Refuge (SPNWR), Sandy Point, St. Croix, US Virgin Islands, has been comprehensively studied since 1981. Nesting and hatching data are reported here for the first 30 yrs of the research and conservation project. Because of intense nest relocation and conservation efforts, the population initially showed a steady increase in numbers, with the most dramatic rise occurring between 1997 and 2001. In spite of continued efforts, however, this recovery began to stall in the decade from 2000 to 2010. Analysis of nesting data, including specific reproductive parameters such as recruitment rate, remigration interval, and productivity (number of nests laid, hatching success) during this time frame, in conjunction with historical data, provided an opportunity to assess the contribution of these factors to the population dynamics at Sandy Point. Annual reproductive data demonstrated that regardless of overall nesting numbers, odd years consistently exhibited higher nesting numbers (115.6 ± 18.58) than even years (68.4 ± 7.63) (p < 0.01). The average annual remigration interval increased over the study period with a record high of 3.41 ± 0.18 yrs observed in 2008. A steady decline in average nests laid was observed (R2 = 0.84) between 1992 and 2010, with a record low of 3.60 ± 2.16 nests per turtle in 2010. Hatching success varied over the 30-yr period from a project low of 40.28% ± 23.20% in 2005 to a record high of 67.80% ± 20.31% in 1991. Mean overall hatching success for the first 30 yrs of the project was 58.50% ± 7.75%. Hatching success declined over the course of the project, and the number of hatchlings produced per turtle declined in the 2000s. These factors contributed to a decrease in population productivity and may ultimately have inhibited continued population growth. Over the study period, a stable percentage of remigrants continued to nest at Sandy Point. However, a decreased number and percentage of neophytes was observed, suggesting either a delayed or a decreased recruitment, possibly due to increased age to sexual maturity, an increased mortality of early life stages, or a change in food resources at foraging grounds. These results suggest a population that has slowed growth and that may begin to decline in the future. Further research needs to be conducted to understand possible maternal, physiological, and environmental factors that are impacting these reproductive parameters and, ultimately, affecting the population dynamics at SPNWR.
{"title":"Reproductive Biology of Atlantic Leatherback Sea Turtles at Sandy Point, St. Croix: The First 30 Years","authors":"Jeanne A. Garner, D. Mackenzie, D. Gatlin","doi":"10.2744/CCB-1224.1","DOIUrl":"https://doi.org/10.2744/CCB-1224.1","url":null,"abstract":"Abstract The nesting population of leatherback sea turtles at the Sandy Point National Wildlife Refuge (SPNWR), Sandy Point, St. Croix, US Virgin Islands, has been comprehensively studied since 1981. Nesting and hatching data are reported here for the first 30 yrs of the research and conservation project. Because of intense nest relocation and conservation efforts, the population initially showed a steady increase in numbers, with the most dramatic rise occurring between 1997 and 2001. In spite of continued efforts, however, this recovery began to stall in the decade from 2000 to 2010. Analysis of nesting data, including specific reproductive parameters such as recruitment rate, remigration interval, and productivity (number of nests laid, hatching success) during this time frame, in conjunction with historical data, provided an opportunity to assess the contribution of these factors to the population dynamics at Sandy Point. Annual reproductive data demonstrated that regardless of overall nesting numbers, odd years consistently exhibited higher nesting numbers (115.6 ± 18.58) than even years (68.4 ± 7.63) (p < 0.01). The average annual remigration interval increased over the study period with a record high of 3.41 ± 0.18 yrs observed in 2008. A steady decline in average nests laid was observed (R2 = 0.84) between 1992 and 2010, with a record low of 3.60 ± 2.16 nests per turtle in 2010. Hatching success varied over the 30-yr period from a project low of 40.28% ± 23.20% in 2005 to a record high of 67.80% ± 20.31% in 1991. Mean overall hatching success for the first 30 yrs of the project was 58.50% ± 7.75%. Hatching success declined over the course of the project, and the number of hatchlings produced per turtle declined in the 2000s. These factors contributed to a decrease in population productivity and may ultimately have inhibited continued population growth. Over the study period, a stable percentage of remigrants continued to nest at Sandy Point. However, a decreased number and percentage of neophytes was observed, suggesting either a delayed or a decreased recruitment, possibly due to increased age to sexual maturity, an increased mortality of early life stages, or a change in food resources at foraging grounds. These results suggest a population that has slowed growth and that may begin to decline in the future. Further research needs to be conducted to understand possible maternal, physiological, and environmental factors that are impacting these reproductive parameters and, ultimately, affecting the population dynamics at SPNWR.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1224.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43219452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amanda Fernandes, A. Bondioli, M. Solé, A. Schiavetti
Abstract This study was conducted in São Sebastião Channel, along the Southern Brazil Platform, and describes the occurrence of 3 species of sea turtles in the area, their main behavioral patterns, and the anthropogenic-related threats. Green turtles (Chelonia mydas) showed a preference for a site covered by Halodule spp. seagrass and hawksbill turtles (Eretmochelys imbricata) showed a preference for a sheltered bay with little wave action and the presence of rocks covered with Palythoa caribaeorum. These sites exhibited different characteristics due to the presence of ocean currents and variable habitat types in the Channel. This study enabled the description of the São Sebastião Channel as a foraging and resting area for sea turtles. We also suggest changing the category of the local marine protected area to enable better protection of turtles.
摘要本研究以巴西南台地区的s o sebasti海峡为研究对象，分析了该海域3种海龟的分布、主要行为模式及受到的人类活动威胁。绿海龟(Chelonia mydas)偏爱被Halodule spp.海草覆盖的地点，玳瑁(Eretmochelys brbricata)偏爱波浪作用小、岩石覆盖Palythoa caribaeorum的隐蔽海湾。由于海流的存在和英吉利海峡不同的生境类型，这些地点表现出不同的特征。这项研究使 o sebasti o海峡成为海龟觅食和休息的区域。我们亦建议更改本地海洋保护区的类别，以更好地保护海龟。
{"title":"Seasonal Variation in the Behavior of Sea Turtles at a Brazilian Foraging Area","authors":"Amanda Fernandes, A. Bondioli, M. Solé, A. Schiavetti","doi":"10.2744/CCB-1200.1","DOIUrl":"https://doi.org/10.2744/CCB-1200.1","url":null,"abstract":"Abstract This study was conducted in São Sebastião Channel, along the Southern Brazil Platform, and describes the occurrence of 3 species of sea turtles in the area, their main behavioral patterns, and the anthropogenic-related threats. Green turtles (Chelonia mydas) showed a preference for a site covered by Halodule spp. seagrass and hawksbill turtles (Eretmochelys imbricata) showed a preference for a sheltered bay with little wave action and the presence of rocks covered with Palythoa caribaeorum. These sites exhibited different characteristics due to the presence of ocean currents and variable habitat types in the Channel. This study enabled the description of the São Sebastião Channel as a foraging and resting area for sea turtles. We also suggest changing the category of the local marine protected area to enable better protection of turtles.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1200.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41725793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Julia Azanza-Ricardo, M. E. Martin, G. G. Sansón, E. Harrison, Y. M. Cruz, F. Bretos
Abstract Changing climate is affecting life all over the world. The loggerhead turtle (Caretta caretta) is one of the most vulnerable turtle species to climate change, particularly with regard to sex determination being affected by high temperatures in most nesting areas, such as the Cuban archipelago. As yet, species information is scarce for the Cuban archipelago as a whole. This study provides information about loggerheads in order to determine the possible effects of climate change on this species, especially in Guanahacabibes. We monitored 10 beaches along the southernmost coast of the Guanahacabibes Peninsula for 18 yrs (1998–2015), from May to September of each year, to determine nesting activity and density. Females were measured and tagged and the remigration interval was determined. Temporal variation was reflected in apparent peaks in reproductive activity on a biennial cycle. We found intraseasonal variation with the highest nesting activity in June, with a 15% increase in nesting activity in the second half of that month. Reduction in clutch size, incubation period, and hatchling size, as well as a potential feminization of hatchling production, indicates a possible effect of climate change in reproductive success. Our results are a first attempt at characterizing Guanahacabibes populations and have great value for establishing conservation priorities such as the protection of the nesting females and control of incubation environment in the face of global climate change within the context of national management plans.
{"title":"Possible Effect of Global Climate Change on Caretta caretta (Testudines, Cheloniidae) Nesting Ecology at Guanahacabibes Peninsula, Cuba","authors":"Julia Azanza-Ricardo, M. E. Martin, G. G. Sansón, E. Harrison, Y. M. Cruz, F. Bretos","doi":"10.2744/CCB-1241.1","DOIUrl":"https://doi.org/10.2744/CCB-1241.1","url":null,"abstract":"Abstract Changing climate is affecting life all over the world. The loggerhead turtle (Caretta caretta) is one of the most vulnerable turtle species to climate change, particularly with regard to sex determination being affected by high temperatures in most nesting areas, such as the Cuban archipelago. As yet, species information is scarce for the Cuban archipelago as a whole. This study provides information about loggerheads in order to determine the possible effects of climate change on this species, especially in Guanahacabibes. We monitored 10 beaches along the southernmost coast of the Guanahacabibes Peninsula for 18 yrs (1998–2015), from May to September of each year, to determine nesting activity and density. Females were measured and tagged and the remigration interval was determined. Temporal variation was reflected in apparent peaks in reproductive activity on a biennial cycle. We found intraseasonal variation with the highest nesting activity in June, with a 15% increase in nesting activity in the second half of that month. Reduction in clutch size, incubation period, and hatchling size, as well as a potential feminization of hatchling production, indicates a possible effect of climate change in reproductive success. Our results are a first attempt at characterizing Guanahacabibes populations and have great value for establishing conservation priorities such as the protection of the nesting females and control of incubation environment in the face of global climate change within the context of national management plans.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1241.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47290907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Many species of reptiles maintain their body temperature behaviorally in a narrow range, even in the presence of considerable environmental temperature variation, by choosing microhabitats with different temperatures. In freshwater turtles, thermoregulation is generally achieved by aerial basking, even though they perform all other vital activities such as food consumption and reproduction in the water. Therefore, time budgets related to basking should be constrained and individuals should maximize the energy per unit time during basking, potentially by increasing basking frequency at noon during colder months and increasing use of basking when water temperature decreases. We analyzed basking behavior during the austral summer to study the effects of season, water temperature, and time of day in 2 South American freshwater turtles: Trachemys dorbigni (black-bellied slider) and Phrynops hilarii (Hilaire's side-necked turtle). We found that water temperature negatively affected basking frequency in both species differently; basking by T. dorbigni occurred on a diel cycle while basking by P. hilarii occurred on a seasonal level. Both species showed a bell-shaped basking frequency during the day, with more individuals basking at noon than in the morning and afternoon. However, only P. hilarii showed a significant seasonal effect on basking, with basking frequency decreasing in summer. These results suggest the thermoregulatory role of basking behavior in 2 austral turtle species and its trade-off with other vital activities.
{"title":"Daily and Seasonal Basking Behavior in Two South American Freshwater Turtles, Trachemys dorbigni and Phrynops hilarii","authors":"Sabrina Clavijo-Baquet, Larisa Magnone","doi":"10.2744/CCB-1201.1","DOIUrl":"https://doi.org/10.2744/CCB-1201.1","url":null,"abstract":"Abstract Many species of reptiles maintain their body temperature behaviorally in a narrow range, even in the presence of considerable environmental temperature variation, by choosing microhabitats with different temperatures. In freshwater turtles, thermoregulation is generally achieved by aerial basking, even though they perform all other vital activities such as food consumption and reproduction in the water. Therefore, time budgets related to basking should be constrained and individuals should maximize the energy per unit time during basking, potentially by increasing basking frequency at noon during colder months and increasing use of basking when water temperature decreases. We analyzed basking behavior during the austral summer to study the effects of season, water temperature, and time of day in 2 South American freshwater turtles: Trachemys dorbigni (black-bellied slider) and Phrynops hilarii (Hilaire's side-necked turtle). We found that water temperature negatively affected basking frequency in both species differently; basking by T. dorbigni occurred on a diel cycle while basking by P. hilarii occurred on a seasonal level. Both species showed a bell-shaped basking frequency during the day, with more individuals basking at noon than in the morning and afternoon. However, only P. hilarii showed a significant seasonal effect on basking, with basking frequency decreasing in summer. These results suggest the thermoregulatory role of basking behavior in 2 austral turtle species and its trade-off with other vital activities.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1201.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41586958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Satomi Kondo, Y. Morimoto, Takayuki Sato, H. Suganuma
Abstract The Ogasawara Islands in Japan represent an important rookery for green sea turtles (Chelonia mydas) in the Pacific Ocean. The marine turtle population in these islands was severely depleted due to overexploitation in the 1800s; however, continuous nesting surveys starting in 1975 showed signs of a gradual recovery, and an upward trend of nesting females has been observed in recent years. The Japanese government undertook a “hatch and release project” to recover the turtle stock in 1910 as the world's first attempt of a sea turtle hatchery. A total of more than 251,000 hatchlings were released into the wild as a part of the project; however, its contribution to the recent increase in nesting females is not well understood. The increase in nesting females may be attributed to the temporary suspension of the turtle harvest and reduction of catch from 1942 to 1968, which allowed for stable production of hatchlings from natural beaches. This study documents the levels of harvest, number of nesting females, and hatchling production at Ogasawara and explores, for the first time, their influence on population dynamics of Ogasawara's green turtles.
{"title":"Factors Affecting the Long-Term Population Dynamics of Green Turtles (Chelonia mydas) in Ogasawara, Japan: Influence of Natural and Artificial Production of Hatchlings and Harvest Pressure","authors":"Satomi Kondo, Y. Morimoto, Takayuki Sato, H. Suganuma","doi":"10.2744/CCB-1222.1","DOIUrl":"https://doi.org/10.2744/CCB-1222.1","url":null,"abstract":"Abstract The Ogasawara Islands in Japan represent an important rookery for green sea turtles (Chelonia mydas) in the Pacific Ocean. The marine turtle population in these islands was severely depleted due to overexploitation in the 1800s; however, continuous nesting surveys starting in 1975 showed signs of a gradual recovery, and an upward trend of nesting females has been observed in recent years. The Japanese government undertook a “hatch and release project” to recover the turtle stock in 1910 as the world's first attempt of a sea turtle hatchery. A total of more than 251,000 hatchlings were released into the wild as a part of the project; however, its contribution to the recent increase in nesting females is not well understood. The increase in nesting females may be attributed to the temporary suspension of the turtle harvest and reduction of catch from 1942 to 1968, which allowed for stable production of hatchlings from natural beaches. This study documents the levels of harvest, number of nesting females, and hatchling production at Ogasawara and explores, for the first time, their influence on population dynamics of Ogasawara's green turtles.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1222.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41962872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The ability to identify the sex of animals accurately is important in population studies. Emydid turtles (Testudines: Emydidae) demonstrate a number of sexually dimorphic characters, including head (cranial) size and structure. Field observations from a long-term study of midland painted turtles (Chrysemys picta marginata) in Algonquin Provincial Park, Ontario, Canada, suggested distinct differences in external head morphology between the sexes. We evaluated these putative sexual differences in C. picta head morphology by conducting a visual questionnaire involving human observers of varying levels of experience (novice, beginner, intermediate, and advanced). Observers were capable of distinguishing the sexes based solely on head morphology with a high degree of accuracy (between 79% and 86% success) across experience levels. Observers identified head shape as a defining character distinguishing the sexes. We suggest that visual questionnaires are a quantifiable method of assessing dimorphic characters that can be used in addition to traditional morphometrics or geometric morphometrics to demonstrate a visual, rather than simply statistical, difference among characters and sexes. Despite the breadth of research conducted on C. picta, our study is among the first to describe, assess, and discuss the functional significance of head dimorphism in this model species.
{"title":"Assessing Head Morphology Dimorphism in the Midland Painted Turtle (Chrysemys picta marginata) Using a Photographic Questionnaire","authors":"Patrick D. Moldowan, R. Brooks, J. Litzgus","doi":"10.2744/CCB-1235.1","DOIUrl":"https://doi.org/10.2744/CCB-1235.1","url":null,"abstract":"Abstract The ability to identify the sex of animals accurately is important in population studies. Emydid turtles (Testudines: Emydidae) demonstrate a number of sexually dimorphic characters, including head (cranial) size and structure. Field observations from a long-term study of midland painted turtles (Chrysemys picta marginata) in Algonquin Provincial Park, Ontario, Canada, suggested distinct differences in external head morphology between the sexes. We evaluated these putative sexual differences in C. picta head morphology by conducting a visual questionnaire involving human observers of varying levels of experience (novice, beginner, intermediate, and advanced). Observers were capable of distinguishing the sexes based solely on head morphology with a high degree of accuracy (between 79% and 86% success) across experience levels. Observers identified head shape as a defining character distinguishing the sexes. We suggest that visual questionnaires are a quantifiable method of assessing dimorphic characters that can be used in addition to traditional morphometrics or geometric morphometrics to demonstrate a visual, rather than simply statistical, difference among characters and sexes. Despite the breadth of research conducted on C. picta, our study is among the first to describe, assess, and discuss the functional significance of head dimorphism in this model species.","PeriodicalId":50703,"journal":{"name":"Chelonian Conservation and Biology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.2744/CCB-1235.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69181021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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