Rui Ma, Shuo Ma, Xu Wei, Jiaxin Zheng, Changqing Yuan, Shunqi Bo, Xiao Yuan, Lei Ji, Zirong Li, Eugeniy Shemyakin, Ivan Tiuvon, Kirill Sharshov, Tianhou Wang, Zhenghuan Wang
Millions of migratory waterfowl winter in the coastal wetlands in Shanghai City, among which Eastern Spot-billed Ducks and Mallards are among the most common species and are sensitive to infection with avian influenza virus. However, information on the migration behaviors of these two species in Northeast Asia is lacking. Therefore, GPS transmitters were used to track the migration of 13 Eastern Spot-billed Ducks and eight Mallards wintering in Shanghai during 2017–2020. Mallards covered a (mean ± standard deviation) migration distance of 1,663.69 ± 1,063.33 km, with wider variation than Eastern Spot-billed Ducks (1,639.24 ± 642.72 km), though the difference was not significant. Both species ended their northward migrations in Northeast Asia encircling the Yellow Sea, mainly in northeastern China. The dynamic Brownian bridge movement model confirmed that multiple stopover sites mainly located in the Korean Peninsula along the Yellow Sea coastline were crucial nodes for maintaining the stability and function of the migration network. This study confirmed the close relationships between habitats in the Korean Peninsula and China, indicating the importance of habitat conservation in related countries to the stability of the migration network. The results of this study additionally highlight the relationships between migration behaviors and outbreaks of avian influenza virus in Northeast Asia.
{"title":"Tracking Migration of Eastern Spot-Billed Ducks Anas zonorhyncha and Mallards Anas platyrhynchos Wintering in Shanghai, China","authors":"Rui Ma, Shuo Ma, Xu Wei, Jiaxin Zheng, Changqing Yuan, Shunqi Bo, Xiao Yuan, Lei Ji, Zirong Li, Eugeniy Shemyakin, Ivan Tiuvon, Kirill Sharshov, Tianhou Wang, Zhenghuan Wang","doi":"10.1675/063.045.0411","DOIUrl":"https://doi.org/10.1675/063.045.0411","url":null,"abstract":"Millions of migratory waterfowl winter in the coastal wetlands in Shanghai City, among which Eastern Spot-billed Ducks and Mallards are among the most common species and are sensitive to infection with avian influenza virus. However, information on the migration behaviors of these two species in Northeast Asia is lacking. Therefore, GPS transmitters were used to track the migration of 13 Eastern Spot-billed Ducks and eight Mallards wintering in Shanghai during 2017–2020. Mallards covered a (mean ± standard deviation) migration distance of 1,663.69 ± 1,063.33 km, with wider variation than Eastern Spot-billed Ducks (1,639.24 ± 642.72 km), though the difference was not significant. Both species ended their northward migrations in Northeast Asia encircling the Yellow Sea, mainly in northeastern China. The dynamic Brownian bridge movement model confirmed that multiple stopover sites mainly located in the Korean Peninsula along the Yellow Sea coastline were crucial nodes for maintaining the stability and function of the migration network. This study confirmed the close relationships between habitats in the Korean Peninsula and China, indicating the importance of habitat conservation in related countries to the stability of the migration network. The results of this study additionally highlight the relationships between migration behaviors and outbreaks of avian influenza virus in Northeast Asia.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135109988","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}
Anthropogenic islands have become important alternative nesting sites for wading birds by providing habitat where natural sites are degraded or absent. However, anthropogenic islands have higher elevations and experience more disturbance than natural sites, which may alter nest predation risk. Yet, little is known about the degree to which wading bird productivity varies between colony types. We used a generalized linear model approach to determine the effect of colony type and resource availability on the species-specific productivity of wading birds at Lake Okeechobee from 2010 to 2019. Great Egret (Ardea alba) productivity did not vary by colony type, whereas Snowy Egret (Egretta thula) and Tricolored Heron (Egretta tricolor) on average produced 0.2 and 0.7 more chicks per hatched nest at natural marsh island colony-sites (n = 6) than at anthropogenic island colony-sites (n = 4), respectively. This suggests that anthropogenic island colony-sites provide lower quality nesting habitat for these species than do marsh colony-sites. However, anthropogenic islands provide nesting habitat in years when marsh colony-sites are limited, and thus increase long-term productivity. Constraints on the ability of anthropogenic islands to support wading bird nesting can be relaxed by optimizing island location and structure during their creation.
{"title":"Productivity and Nestling Mortality for Three Species of Herons at Natural and Anthropogenic Islands","authors":"Jacquelyn D. Evans, Dale E. Gawlik","doi":"10.1675/063.045.0402","DOIUrl":"https://doi.org/10.1675/063.045.0402","url":null,"abstract":"Anthropogenic islands have become important alternative nesting sites for wading birds by providing habitat where natural sites are degraded or absent. However, anthropogenic islands have higher elevations and experience more disturbance than natural sites, which may alter nest predation risk. Yet, little is known about the degree to which wading bird productivity varies between colony types. We used a generalized linear model approach to determine the effect of colony type and resource availability on the species-specific productivity of wading birds at Lake Okeechobee from 2010 to 2019. Great Egret (Ardea alba) productivity did not vary by colony type, whereas Snowy Egret (Egretta thula) and Tricolored Heron (Egretta tricolor) on average produced 0.2 and 0.7 more chicks per hatched nest at natural marsh island colony-sites (n = 6) than at anthropogenic island colony-sites (n = 4), respectively. This suggests that anthropogenic island colony-sites provide lower quality nesting habitat for these species than do marsh colony-sites. However, anthropogenic islands provide nesting habitat in years when marsh colony-sites are limited, and thus increase long-term productivity. Constraints on the ability of anthropogenic islands to support wading bird nesting can be relaxed by optimizing island location and structure during their creation.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135109989","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}
Gravel rooftops are important for nesting Least Terns (Sternula antillarum) in Florida. A network of partners from the Florida Shorebird Alliance (FSA partners) monitor roof-nesting Least Terns by conducting street surveys - a count of flying adults seen from the ground. We used double sampling to adjust street survey data and produce a population estimate for the 2018 nesting season (1 May–20 June). In 2018, FSA partners conducted street surveys at 96% (n = 138) of the active rooftop colonies in the state. In a random subsample (n = 62), we conducted direct counts of breeding adults and produced a detection ratio of 0.61, a ratio estimate of 59.28 ± 5.01 breeding adults/rooftop, and an adjusted population estimate of 8,180 ± 692 breeding adults (95% CI: 6,825–9,536). Cross-validation tests using data collected before and after the 2018 study produced accurate and unbiased population estimates derived from the detection ratio and street surveys. We used available street survey data from 2015 to 2020 and found a 7% population increase. We suggest validating the detection ratio every three years to develop accurate abundance and trend estimates of Florida's roof-nesting Least Terns.
{"title":"Using Double Sampling to Estimate the Population of Least Terns (Sternula antillarum) Nesting on Florida's Rooftops","authors":"Ariam Jiménez, Janell Brush, Ricardo Zambrano, Natasha Warraich, Marianne Korosy","doi":"10.1675/063.045.0408","DOIUrl":"https://doi.org/10.1675/063.045.0408","url":null,"abstract":"Gravel rooftops are important for nesting Least Terns (Sternula antillarum) in Florida. A network of partners from the Florida Shorebird Alliance (FSA partners) monitor roof-nesting Least Terns by conducting street surveys - a count of flying adults seen from the ground. We used double sampling to adjust street survey data and produce a population estimate for the 2018 nesting season (1 May–20 June). In 2018, FSA partners conducted street surveys at 96% (n = 138) of the active rooftop colonies in the state. In a random subsample (n = 62), we conducted direct counts of breeding adults and produced a detection ratio of 0.61, a ratio estimate of 59.28 ± 5.01 breeding adults/rooftop, and an adjusted population estimate of 8,180 ± 692 breeding adults (95% CI: 6,825–9,536). Cross-validation tests using data collected before and after the 2018 study produced accurate and unbiased population estimates derived from the detection ratio and street surveys. We used available street survey data from 2015 to 2020 and found a 7% population increase. We suggest validating the detection ratio every three years to develop accurate abundance and trend estimates of Florida's roof-nesting Least Terns.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"188 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135109987","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}
A Great Blue Heron (Ardea herodias) was observed killing a California butterfly ray (Gymnura marmorata) with a morphological abnormality off coastal California. Even though this heron species has previously been reported actively hunting batoids, this observation is the first documenting of an attack by a bird (or any other predator) on a butterfly ray. The behavior observed in this event adds butterfly rays as potential prey items of A. herodias and provides further insights on both this bird's ecology as a nearshore predator and that of ray species like G. marmorata as important prey.
{"title":"Great Blue Heron (Ardea herodias) Predation on an Abnormal California Butterfly Ray (Gymnura marmorata) and its Ecological Implications","authors":"Victor Bach Muñoz","doi":"10.1675/063.045.0412","DOIUrl":"https://doi.org/10.1675/063.045.0412","url":null,"abstract":"A Great Blue Heron (Ardea herodias) was observed killing a California butterfly ray (Gymnura marmorata) with a morphological abnormality off coastal California. Even though this heron species has previously been reported actively hunting batoids, this observation is the first documenting of an attack by a bird (or any other predator) on a butterfly ray. The behavior observed in this event adds butterfly rays as potential prey items of A. herodias and provides further insights on both this bird's ecology as a nearshore predator and that of ray species like G. marmorata as important prey.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135109992","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}
Understanding habitat use on a fine scale is essential for the development of management plans for threatened and endangered species. Several heavily managed State Wildlife Sanctuaries and National Wildlife Refuges provide critical foraging habitat for the endangered Hawaiian Stilt, or Ae'o (Himantopus mexicanus knudseni). The foraging behavior and habitat use of Hawaiian Stilts at Hāmākua Marsh State Wildlife Sanctuary, O'ahu, Hawai'i was investigated. Foraging tactics, success, and microhabitat were recorded for 227 birds over 24 2-hr periods from September to December 2021. Hawaiian Stilts made the most foraging attempts in shallow (< 8 cm deep) water, and had the most success in intermediate (8–15 cm deep) water. The most commonly recorded foraging tactic was pecking, while the most successful was plunging. Visual tactics were both more common and more successful than tactile. The overall foraging success rate for Hawaiian Stilts in this study was 0.16, markedly less than success rates observed by other researchers in related species. It is possible that prey in Hāmākua Marsh is either less abundant or less vulnerable to capture than in other similar habitats. Our results suggest that future habitat management for Hawaiian Stilts should prioritize areas of shallow water and further investigate food availability.
{"title":"Foraging Behavior of the Hawaiian Stilt (Himantopus mexicanus knudseni) at Hāmākua Marsh, O'ahu, Hawai'i","authors":"Margaret B. Jensen, Irene Liang, Aaron J. Works","doi":"10.1675/063.045.0406","DOIUrl":"https://doi.org/10.1675/063.045.0406","url":null,"abstract":"Understanding habitat use on a fine scale is essential for the development of management plans for threatened and endangered species. Several heavily managed State Wildlife Sanctuaries and National Wildlife Refuges provide critical foraging habitat for the endangered Hawaiian Stilt, or Ae'o (Himantopus mexicanus knudseni). The foraging behavior and habitat use of Hawaiian Stilts at Hāmākua Marsh State Wildlife Sanctuary, O'ahu, Hawai'i was investigated. Foraging tactics, success, and microhabitat were recorded for 227 birds over 24 2-hr periods from September to December 2021. Hawaiian Stilts made the most foraging attempts in shallow (< 8 cm deep) water, and had the most success in intermediate (8–15 cm deep) water. The most commonly recorded foraging tactic was pecking, while the most successful was plunging. Visual tactics were both more common and more successful than tactile. The overall foraging success rate for Hawaiian Stilts in this study was 0.16, markedly less than success rates observed by other researchers in related species. It is possible that prey in Hāmākua Marsh is either less abundant or less vulnerable to capture than in other similar habitats. Our results suggest that future habitat management for Hawaiian Stilts should prioritize areas of shallow water and further investigate food availability.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135109985","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}
The White-eared Night Heron (Gorsachius magnificus) is a poorly known species. Little ecological research has been conducted on this species, and its migration route in particular is poorly understood. Clarification of the migratory routes of this species can enhance our understanding of its distribution and aid its conservation. Here, we identified the wintering and summering sites and characterized the migration route of one White-eared Night Heron by GPS/GSM tracking. Our results indicated that the Nanting River on the China–Myanmar border is the wintering site for this individual, and the Shizhuang River in Nanzhang, Hubei Province, China is the summering site. The heron migrated along the mountains and rested near rivers and reservoirs. This study is the first to reveal the migration route of the White-eared Night Heron. Our findings suggest that this species in Yunnan, Hubei, and Guizhou Provinces is not a resident bird. Generally, these data will aid the conservation of this species, including the development of action plans and the establishment of local nature reserves along its migration route and at wintering, summering, and stopover sites.
{"title":"Northward Migration Route of one White-Eared Night Heron (Gorsachius magnificus) Revealed by GPS/GSM Tracking","authors":"Ru Jia, Dongping Liu, Jian Li, Zengyang Luo, Jianwei Duan, Yong Li, Guoxiang Yang, Guogang Zhang","doi":"10.1675/063.045.0414","DOIUrl":"https://doi.org/10.1675/063.045.0414","url":null,"abstract":"The White-eared Night Heron (Gorsachius magnificus) is a poorly known species. Little ecological research has been conducted on this species, and its migration route in particular is poorly understood. Clarification of the migratory routes of this species can enhance our understanding of its distribution and aid its conservation. Here, we identified the wintering and summering sites and characterized the migration route of one White-eared Night Heron by GPS/GSM tracking. Our results indicated that the Nanting River on the China–Myanmar border is the wintering site for this individual, and the Shizhuang River in Nanzhang, Hubei Province, China is the summering site. The heron migrated along the mountains and rested near rivers and reservoirs. This study is the first to reveal the migration route of the White-eared Night Heron. Our findings suggest that this species in Yunnan, Hubei, and Guizhou Provinces is not a resident bird. Generally, these data will aid the conservation of this species, including the development of action plans and the establishment of local nature reserves along its migration route and at wintering, summering, and stopover sites.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135110219","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}
M. P. Rosas‐Hernandez, Y. V. Albores‐Barajas, C. Soldatini, J. Herguera, Giacomo Dell ' Omo
Abstract. Seabirds utilize different foraging strategies based on their physical needs and environmental conditions during the stages of their reproductive cycle. During their breeding season, seabirds assume a central-place foraging strategy, while after the reproductive season, during their molt, they migrate to distant non-breeding grounds where they remain for several months. Until recently, little was known about their distribution and ecology during migration. This gap in knowledge regarding large-scale movements and ecology could be filled by analyzing isotopic ratios of carbon (δ13C) and nitrogen (δ15N) in the feathers. Analyzing stable isotope ratios provides insights into the species' foraging ecology and variations along the molting period. We first ascertained the molting strategy of the Black-vented Shearwaters (Puffinus opisthomelas). We then inferred their non-breeding period distribution range and variations in the trophic niche by analysing stable isotopes in feathers. The observed δ13C values reveal that these birds all migrate to similar terminal non-breeding areas. Values of δ15N were similar between sexes during winter and up to the reproductive period; however, their levels were distinct during the post-breeding period. Sexes exploited slightly different trophic levels during the post-breeding period, differently using coastal and pelagic waters, likely to reduce competition during their post-breeding molt.
{"title":"The Isotopic Pattern Variability in the Breeding and Non-Breeding Black-Vented Shearwater","authors":"M. P. Rosas‐Hernandez, Y. V. Albores‐Barajas, C. Soldatini, J. Herguera, Giacomo Dell ' Omo","doi":"10.1675/063.045.0309","DOIUrl":"https://doi.org/10.1675/063.045.0309","url":null,"abstract":"Abstract. Seabirds utilize different foraging strategies based on their physical needs and environmental conditions during the stages of their reproductive cycle. During their breeding season, seabirds assume a central-place foraging strategy, while after the reproductive season, during their molt, they migrate to distant non-breeding grounds where they remain for several months. Until recently, little was known about their distribution and ecology during migration. This gap in knowledge regarding large-scale movements and ecology could be filled by analyzing isotopic ratios of carbon (δ13C) and nitrogen (δ15N) in the feathers. Analyzing stable isotope ratios provides insights into the species' foraging ecology and variations along the molting period. We first ascertained the molting strategy of the Black-vented Shearwaters (Puffinus opisthomelas). We then inferred their non-breeding period distribution range and variations in the trophic niche by analysing stable isotopes in feathers. The observed δ13C values reveal that these birds all migrate to similar terminal non-breeding areas. Values of δ15N were similar between sexes during winter and up to the reproductive period; however, their levels were distinct during the post-breeding period. Sexes exploited slightly different trophic levels during the post-breeding period, differently using coastal and pelagic waters, likely to reduce competition during their post-breeding molt.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"21 1","pages":"300 - 311"},"PeriodicalIF":0.3,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81343006","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}
Ryan M. Dinehart, Dustin E. Brewer, T. M. Gehring, K. Pangle, D. Uzarski
Abstract. We examined effects of Phragmites australis on four marsh-dependent birds [Least Bittern (Ixobrychus exilis), Marsh Wren (Cistothorus palustris), Sora (Porzana carolina), Virginia Rail (Rallus limicola)] during water-level fluctuations within Saginaw Bay, Michigan. During 2002–2004 (pre-Phragmites expansion), 2008–2010 (Phragmites expansion), and 2014–2015 (increasing water levels-decreasing Phragmites coverage), we measured area of native vegetation, area of Phragmites, and distance between native vegetation patches at 21 coastal wetlands. We calculated ecologically scaled landscape indices (ESLIs) to determine changes in carrying capacity and connectivity for each species in the wetland landscape through time. Carrying capacity and connectivity values were greatest for all species during 2002–2004, likely due to the limited influence of Phragmites on the landscape during that period. By 2008-2010, expansion of Phragmites severely reduced marsh bird habitat carrying capacity and connectivity of wetland landscapes. Rising water levels, associated with reduced Phragmites cover, resulted in further slight reductions in connectivity and slight increases in amount of wetland habitat. Data from a subset of focal sites in Saginaw Bay suggested that marsh birds responded positively to increasing water levels. Our study demonstrates utility of ESLIs as a conservation tool for identifying key factors that impact landscape structure and avian community composition over time.
摘要在密歇根州萨吉诺湾，我们研究了芦苇在水位波动期间对四种依赖沼泽的鸟类[最小麻鸦(Ixobrychus exilis)，沼泽鹪鹩(Cistothorus palustris)， Sora (Porzana carolina)， Virginia Rail (Rallus limicola)]的影响。在2002-2004年(芦苇扩张前期)、2008-2010年(芦苇扩张期)和2014-2015年(芦苇覆盖期)对21个滨海湿地的原生植被面积、芦苇面积和原生植被斑块之间的距离进行了测量。通过计算生态尺度景观指数(ESLIs)来确定湿地景观中各物种的承载能力和连通性随时间的变化。在2002-2004年期间，所有物种的承载力和连通性值最高，这可能是由于芦苇在此期间对景观的影响有限。2008-2010年芦苇的扩张严重降低了湿地鸟类栖息地的承载能力和湿地景观的连通性。水位上升与芦苇覆盖减少有关，导致连通性进一步略有下降，湿地栖息地数量略有增加。来自萨吉诺湾集中地点子集的数据表明，沼泽鸟类对不断上升的水位做出了积极的反应。我们的研究证明了ESLIs作为一种保护工具的实用性，它可以识别影响景观结构和鸟类群落组成的关键因素。
{"title":"Ecologically Scaled Responses of Marsh Birds to Invasive Phragmites Expansion and Water-Level Fluctuations","authors":"Ryan M. Dinehart, Dustin E. Brewer, T. M. Gehring, K. Pangle, D. Uzarski","doi":"10.1675/063.045.0302","DOIUrl":"https://doi.org/10.1675/063.045.0302","url":null,"abstract":"Abstract. We examined effects of Phragmites australis on four marsh-dependent birds [Least Bittern (Ixobrychus exilis), Marsh Wren (Cistothorus palustris), Sora (Porzana carolina), Virginia Rail (Rallus limicola)] during water-level fluctuations within Saginaw Bay, Michigan. During 2002–2004 (pre-Phragmites expansion), 2008–2010 (Phragmites expansion), and 2014–2015 (increasing water levels-decreasing Phragmites coverage), we measured area of native vegetation, area of Phragmites, and distance between native vegetation patches at 21 coastal wetlands. We calculated ecologically scaled landscape indices (ESLIs) to determine changes in carrying capacity and connectivity for each species in the wetland landscape through time. Carrying capacity and connectivity values were greatest for all species during 2002–2004, likely due to the limited influence of Phragmites on the landscape during that period. By 2008-2010, expansion of Phragmites severely reduced marsh bird habitat carrying capacity and connectivity of wetland landscapes. Rising water levels, associated with reduced Phragmites cover, resulted in further slight reductions in connectivity and slight increases in amount of wetland habitat. Data from a subset of focal sites in Saginaw Bay suggested that marsh birds responded positively to increasing water levels. Our study demonstrates utility of ESLIs as a conservation tool for identifying key factors that impact landscape structure and avian community composition over time.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"1 1","pages":"225 - 236"},"PeriodicalIF":0.3,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91222970","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. Wetland degradation throughout the interior of North America has resulted in a loss of breeding habitat for many waterbird species. The Black Tern (Chlidonias niger) is an obligate marsh-breeding colonial waterbird that has experienced widespread, long-term population declines. Habitat loss and degradation through agricultural conversion, wetland drainage, and agrochemical runoff have been identified as key threats, and studies have suggested that a decline in breeding habitat may be a contributing factor to population declines. Habitat association studies have noted relationships between Black Terns and wetland characteristics, including both local-scale factors such as vegetation type, and landscape-scale factors such as wetland density. However, similar studies have not been conducted in Saskatchewan, the core of the species range in North America. We used high-resolution remotely-sensed imagery to relate habitat, land use, and geographic covariates at wetlands in Saskatchewan to the occurrence of breeding Black Terns and numbers at their colonies. We found that colony occurrence was positively associated with the extent of emergent aquatic vegetation present at a wetland. There was a strong non-linear effect of latitude, whereby colony occurrence and abundance were highest at mid-latitudes in Saskatchewan, corresponding to the boreal transition zone between the prairies to the south and boreal forest to the north. Our results suggest that Black Terns may be first selecting habitat at the landscape scale, perhaps in relation to wetland density, then occupying specific breeding colonies based on wetland characteristics.
{"title":"Assessing Black Tern (Chlidonias niger) Habitat Associations in Saskatchewan, Canada, Using Aerial Imagery","authors":"N. Shephard, M. Reudink, A. McKellar","doi":"10.1675/063.045.0304","DOIUrl":"https://doi.org/10.1675/063.045.0304","url":null,"abstract":"Abstract. Wetland degradation throughout the interior of North America has resulted in a loss of breeding habitat for many waterbird species. The Black Tern (Chlidonias niger) is an obligate marsh-breeding colonial waterbird that has experienced widespread, long-term population declines. Habitat loss and degradation through agricultural conversion, wetland drainage, and agrochemical runoff have been identified as key threats, and studies have suggested that a decline in breeding habitat may be a contributing factor to population declines. Habitat association studies have noted relationships between Black Terns and wetland characteristics, including both local-scale factors such as vegetation type, and landscape-scale factors such as wetland density. However, similar studies have not been conducted in Saskatchewan, the core of the species range in North America. We used high-resolution remotely-sensed imagery to relate habitat, land use, and geographic covariates at wetlands in Saskatchewan to the occurrence of breeding Black Terns and numbers at their colonies. We found that colony occurrence was positively associated with the extent of emergent aquatic vegetation present at a wetland. There was a strong non-linear effect of latitude, whereby colony occurrence and abundance were highest at mid-latitudes in Saskatchewan, corresponding to the boreal transition zone between the prairies to the south and boreal forest to the north. Our results suggest that Black Terns may be first selecting habitat at the landscape scale, perhaps in relation to wetland density, then occupying specific breeding colonies based on wetland characteristics.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"22 1","pages":"247 - 258"},"PeriodicalIF":0.3,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89264534","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}
Emanuele Fasola, F. Stefani, G. Forcina, M. Fasola, Enrico Viganò, A. Doroșencu, J. S. Monrós, M. Morganti
Abstract. Ardeidae tend to exhibit low sexual dimorphism, both in size and plumage coloration, making sex attribution in the field challenging for both birdwatchers and ringers. Here, we assessed whether biometrics and plumage patterns are a good proxy for sex assignment in the Purple Heron (Ardea purpurea). We based our work on 27 molecularly-sexed free-living adults captured in Italy and Romania during the breeding season from 2018 to 2021. We found significant sexual size dimorphism in the beak, which resulted longer in males, but not in weight, wing, tarsus or sternum length. Birds with darker plumages, stronger contrast between reddish ornamental feathers and blackish mantle were classified as males, allowing for correct sex attribution in 70% of the males and 73 % of the females. On the one hand, we concluded that molecular sexing is the most reliable approach for sex attribution in this species. On the other hand, we also found that trained ringers or expert observers may achieve satisfactory sex attribution rates either based on biometrics or accurate plumage observation, possibly even from a distance.
{"title":"Exploratory Analyses of Sexual Size Dimorphism (SSD) and Sexual Dichromatism (SD) in Free-Living Adult Purple Herons (Ardea purpurea)","authors":"Emanuele Fasola, F. Stefani, G. Forcina, M. Fasola, Enrico Viganò, A. Doroșencu, J. S. Monrós, M. Morganti","doi":"10.1675/063.045.0314","DOIUrl":"https://doi.org/10.1675/063.045.0314","url":null,"abstract":"Abstract. Ardeidae tend to exhibit low sexual dimorphism, both in size and plumage coloration, making sex attribution in the field challenging for both birdwatchers and ringers. Here, we assessed whether biometrics and plumage patterns are a good proxy for sex assignment in the Purple Heron (Ardea purpurea). We based our work on 27 molecularly-sexed free-living adults captured in Italy and Romania during the breeding season from 2018 to 2021. We found significant sexual size dimorphism in the beak, which resulted longer in males, but not in weight, wing, tarsus or sternum length. Birds with darker plumages, stronger contrast between reddish ornamental feathers and blackish mantle were classified as males, allowing for correct sex attribution in 70% of the males and 73 % of the females. On the one hand, we concluded that molecular sexing is the most reliable approach for sex attribution in this species. On the other hand, we also found that trained ringers or expert observers may achieve satisfactory sex attribution rates either based on biometrics or accurate plumage observation, possibly even from a distance.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"79 1","pages":"354 - 360"},"PeriodicalIF":0.3,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78736852","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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