Serina Serré, Courtney Irvine, Katie Lockhart, Craig E. Hebert
Abstract. Herring Gull (Larus argentatus) populations in Pukaskwa National Park have declined by 70% over the last 40 years. Populations of avian predators that prey on Herring Gulls have increased which could be a significant factor impacting gull populations. Here, we investigate Herring Gull daytime and nighttime nest attentiveness at locations with and without evidence of nocturnal predators. In 2017, Herring Gull nest attentiveness was examined at two sites using remote cameras. At one of those sites Great Horned Owl (Bubo virginianus) predation was observed, and gull nighttime nest attentiveness was lower there than at the site where owls were not observed. There were no inter-site differences in daytime nest attentiveness. In 2018, Herring Gull nest attentiveness was further investigated at the site where owls were present. At that site, Herring Gull nighttime nest attentiveness was significantly lower than during the day. Extended periods of absence of gulls from their nests during the night corresponded with the presence of owls. Predation of nest contents, in addition to the effects of other environmental stressors, are likely contributing to declines in Pukaskwa National Park's Herring Gull population.
{"title":"Great Horned Owls Affect Herring Gull Nest Attentiveness","authors":"Serina Serré, Courtney Irvine, Katie Lockhart, Craig E. Hebert","doi":"10.1675/063.046.0104","DOIUrl":"https://doi.org/10.1675/063.046.0104","url":null,"abstract":"Abstract. Herring Gull (Larus argentatus) populations in Pukaskwa National Park have declined by 70% over the last 40 years. Populations of avian predators that prey on Herring Gulls have increased which could be a significant factor impacting gull populations. Here, we investigate Herring Gull daytime and nighttime nest attentiveness at locations with and without evidence of nocturnal predators. In 2017, Herring Gull nest attentiveness was examined at two sites using remote cameras. At one of those sites Great Horned Owl (Bubo virginianus) predation was observed, and gull nighttime nest attentiveness was lower there than at the site where owls were not observed. There were no inter-site differences in daytime nest attentiveness. In 2018, Herring Gull nest attentiveness was further investigated at the site where owls were present. At that site, Herring Gull nighttime nest attentiveness was significantly lower than during the day. Extended periods of absence of gulls from their nests during the night corresponded with the presence of owls. Predation of nest contents, in addition to the effects of other environmental stressors, are likely contributing to declines in Pukaskwa National Park's Herring Gull population.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"181 ","pages":"24 - 30"},"PeriodicalIF":0.3,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139250566","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}
Alyssa G. Leicht, D. Robinette, Meredith L. Elliott, Michael H. Horn
Abstract. We evaluated diet and diet assessment methods for the California Least Tern (Sternula antillarum browni) at two nesting sites in California over 12 years (2001–2012). California Least Tern diets at Alameda Point (37° 47′ 14″ N, 122° 19′ 12″ W), an estuarine site, and Purisima Point (34° 46′ 39″ N, 120° 37′ 35″ W), an open coast site, were compared using dropped fish and hard parts (otoliths and scales) from regurgitated pellets and fecal samples. SIMPER analyses, Kendall's tau, Kruskal-Wallis, Dunn's test, rank-sum tests, and Welch's t-test determined any differences in assessment methods, chick and adult diets, and sizes of prey items. Diet composition differed between sites for both dropped fish (25% similar) and fecal samples (26%). Assessment methods showed similar results at Alameda Point (79%) for dropped fish and fecal samples but not at Purisima Point when comparing dropped fish to fecal samples (12%) and fecal samples to regurgitated pellets (19%). There was no difference in diet composition at either site or between any method using adult-only samples. All differences in diet composition appeared during the rearing/fledging stage. Fish species dropped at both sites were deeper-bodied (17 mm) than those consumed (11.9 mm), with terns at Purisima Point dropping deep-bodied species typically not consumed and those at Alameda Point dropping larger individuals of usually-consumed species. When comparing adult and chick diets at Alameda Point using fecal samples, composition was similar, and chicks ate larger prey. Our results suggest that more than one assessment method is necessary to provide a complete dietary picture.
{"title":"Comparison of Diets in the California Least Tern (Sternula antillarum browni) at Two Sites in Central California, U.S.A.","authors":"Alyssa G. Leicht, D. Robinette, Meredith L. Elliott, Michael H. Horn","doi":"10.1675/063.046.0109","DOIUrl":"https://doi.org/10.1675/063.046.0109","url":null,"abstract":"Abstract. We evaluated diet and diet assessment methods for the California Least Tern (Sternula antillarum browni) at two nesting sites in California over 12 years (2001–2012). California Least Tern diets at Alameda Point (37° 47′ 14″ N, 122° 19′ 12″ W), an estuarine site, and Purisima Point (34° 46′ 39″ N, 120° 37′ 35″ W), an open coast site, were compared using dropped fish and hard parts (otoliths and scales) from regurgitated pellets and fecal samples. SIMPER analyses, Kendall's tau, Kruskal-Wallis, Dunn's test, rank-sum tests, and Welch's t-test determined any differences in assessment methods, chick and adult diets, and sizes of prey items. Diet composition differed between sites for both dropped fish (25% similar) and fecal samples (26%). Assessment methods showed similar results at Alameda Point (79%) for dropped fish and fecal samples but not at Purisima Point when comparing dropped fish to fecal samples (12%) and fecal samples to regurgitated pellets (19%). There was no difference in diet composition at either site or between any method using adult-only samples. All differences in diet composition appeared during the rearing/fledging stage. Fish species dropped at both sites were deeper-bodied (17 mm) than those consumed (11.9 mm), with terns at Purisima Point dropping deep-bodied species typically not consumed and those at Alameda Point dropping larger individuals of usually-consumed species. When comparing adult and chick diets at Alameda Point using fecal samples, composition was similar, and chicks ate larger prey. Our results suggest that more than one assessment method is necessary to provide a complete dietary picture.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"37 2","pages":"67 - 77"},"PeriodicalIF":0.3,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139248541","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}
Katharine S. Goodenough, Robert T. Patton, Julio Lorda
Large scale oceanic processes can have profound consequences for marine and coastal food webs. Mortality and reproductive related impacts to seabirds have been documented for decades, and current research suggests that dietary flexibility may be a key component by which birds can mitigate environmental variation. Our motivation for this research was to better understand how a dietary generalist in the coastal environment responds to changes in prey food availability. The Gull-billed Tern Gelochelidon nilotica is a coastal nesting species that has an opportunistic generalist diet. We monitored both tern diet and density of a main prey resource to examine how responsive these terns are to annual variation in prey resources. Our results documented that the loss of a ubiquitous prey resource did not appear to influence tern annual reproductive success even though, in some years, Emerita analoga comprised greater than 70% of Gull-billed Tern diet. During breeding seasons with warmer than average sea surface temperatures, the Gull-billed Tern switched to a more terrestrial diet and focused aquatic foraging activities upon crustacean species that are more tolerant of warmer water temperatures. Dietary plasticity can be beneficial to mitigate variation in prey resource availability and impacts on reproductive success, and the ability to respond rapidly to changes in resources may play an important role in how coastal species can acclimate or adapt to annual changes in the prey base.
{"title":"Dietary Plasticity Mitigates Impacts to Reproduction for the Gull-Billed Tern Gelochelidon nilotica During Abnormally Warm Sea Surface Temperature Events in California, U.S.A.","authors":"Katharine S. Goodenough, Robert T. Patton, Julio Lorda","doi":"10.1675/063.045.0409","DOIUrl":"https://doi.org/10.1675/063.045.0409","url":null,"abstract":"Large scale oceanic processes can have profound consequences for marine and coastal food webs. Mortality and reproductive related impacts to seabirds have been documented for decades, and current research suggests that dietary flexibility may be a key component by which birds can mitigate environmental variation. Our motivation for this research was to better understand how a dietary generalist in the coastal environment responds to changes in prey food availability. The Gull-billed Tern Gelochelidon nilotica is a coastal nesting species that has an opportunistic generalist diet. We monitored both tern diet and density of a main prey resource to examine how responsive these terns are to annual variation in prey resources. Our results documented that the loss of a ubiquitous prey resource did not appear to influence tern annual reproductive success even though, in some years, Emerita analoga comprised greater than 70% of Gull-billed Tern diet. During breeding seasons with warmer than average sea surface temperatures, the Gull-billed Tern switched to a more terrestrial diet and focused aquatic foraging activities upon crustacean species that are more tolerant of warmer water temperatures. Dietary plasticity can be beneficial to mitigate variation in prey resource availability and impacts on reproductive success, and the ability to respond rapidly to changes in resources may play an important role in how coastal species can acclimate or adapt to annual changes in the prey base.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"34 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":"135109986","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}
Daniel P. Collins, Matthew A. Boggie, Kammie L. Kruse, Courtenay M. Conring, J. Patrick Donnelly, Warren C. Conway, Blake A. Grisham
Wetlands in arid and semiarid regions are recognized as priority ecosystems for conservation of wetland-dependent species in these systems. Evaluation of habitat selection is necessary for effective habitat management and, consequently, population management. The Lower Colorado River Valley population of Greater Sandhill Cranes (Antigone canadensis tabida), winters exclusively in portions of southwestern Arizona and southeastern California. Therefore, there is a need for information pertaining to winter habitat selection to guide management decisions. We attached solar-powered satellite platform transmitter terminals to greater Sandhill Cranes and used daily global positioning system locations. Each used location paired with 10 randomly generated locations had equal probability of drawing any of the randomly generated locations. We evaluated habitat selection and found the model that included land use type (β = –5.85, SE = 0.23, P < 0.001) and distance to roost (β = –4.61, SE = 0.16, P < 0.001) as interactive effects was the most supported model in the candidate set. Our results emphasize the importance of maintaining wetlands in close proximity (∼ 5 km) to selected land use types, which can be challenging to manage for in arid systems but are particularly necessary for this high conservation priority population of greater Sandhill Cranes.
干旱半干旱区湿地被认为是湿地依赖物种优先保护的生态系统。对生境选择的评价对于有效的生境管理和种群管理是必要的。科罗拉多河谷下游大沙丘鹤(Antigone canadensis tabida)的种群，只在亚利桑那州西南部和加利福尼亚州东南部的部分地区过冬。因此，需要有关冬季栖息地选择的信息来指导管理决策。我们将太阳能卫星平台发射机终端安装在沙丘起重机上，并使用每日全球定位系统定位。每个使用的位置与10个随机生成的位置配对，绘制任意随机生成的位置的概率相等。结果表明，考虑土地利用类型(β = -5.85, SE = 0.23, P < 0.001)和栖息地距离(β = -4.61, SE = 0.16, P < 0.001)的交互效应模型是候选集中最受支持的模型。我们的研究结果强调了在选定的土地利用类型附近(~ 5公里)维持湿地的重要性，这在干旱系统中可能具有挑战性，但对于这种高度保护优先的大沙丘鹤种群尤其必要。
{"title":"Roost Sites Influence Habitat Selection of Sandhill Cranes (Antigone canadensis tabida) in Arizona and California","authors":"Daniel P. Collins, Matthew A. Boggie, Kammie L. Kruse, Courtenay M. Conring, J. Patrick Donnelly, Warren C. Conway, Blake A. Grisham","doi":"10.1675/063.045.0407","DOIUrl":"https://doi.org/10.1675/063.045.0407","url":null,"abstract":"Wetlands in arid and semiarid regions are recognized as priority ecosystems for conservation of wetland-dependent species in these systems. Evaluation of habitat selection is necessary for effective habitat management and, consequently, population management. The Lower Colorado River Valley population of Greater Sandhill Cranes (Antigone canadensis tabida), winters exclusively in portions of southwestern Arizona and southeastern California. Therefore, there is a need for information pertaining to winter habitat selection to guide management decisions. We attached solar-powered satellite platform transmitter terminals to greater Sandhill Cranes and used daily global positioning system locations. Each used location paired with 10 randomly generated locations had equal probability of drawing any of the randomly generated locations. We evaluated habitat selection and found the model that included land use type (β = –5.85, SE = 0.23, P < 0.001) and distance to roost (β = –4.61, SE = 0.16, P < 0.001) as interactive effects was the most supported model in the candidate set. Our results emphasize the importance of maintaining wetlands in close proximity (∼ 5 km) to selected land use types, which can be challenging to manage for in arid systems but are particularly necessary for this high conservation priority population of greater Sandhill Cranes.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"31 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":"135109991","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}
In July 2020, an individual considered to be a hybrid between a Cattle Egret (Bubulcus ibis) and a Little Egret (Egretta garzetta) was found in Hashima City, Gifu Prefecture, Japan. The first impression was that the bird was a Little Egret, but detailed observations revealed Cattle Egret characteristics in size and plumage color. The hybrid individual also had partial melanic characteristics. The present study compared the external morphological characteristics of the apparent Cattle Egret and Little Egret hybrid, using observations and measurements obtained from images. The results showed that the tarsus length, the bill length, and the observed ratio of the bill length to the bill depth at the front end of the nostril of the hybrid were intermediate between those of Cattle Egret and Little Egret. There are few accounts of inter-generic hybridization among herons and egrets in nature, with only one report from Japan. This is the first record of hybridization between a Cattle Egret and a Little Egret in nature to our knowledge.
{"title":"A Natural Hybridization between a Cattle Egret (Bubulcus ibis) and a Little Egret (Egretta garzetta) in Japan","authors":"Kanade Komaru, Satoshi Tanaka, Junji Moribe","doi":"10.1675/063.045.0415","DOIUrl":"https://doi.org/10.1675/063.045.0415","url":null,"abstract":"In July 2020, an individual considered to be a hybrid between a Cattle Egret (Bubulcus ibis) and a Little Egret (Egretta garzetta) was found in Hashima City, Gifu Prefecture, Japan. The first impression was that the bird was a Little Egret, but detailed observations revealed Cattle Egret characteristics in size and plumage color. The hybrid individual also had partial melanic characteristics. The present study compared the external morphological characteristics of the apparent Cattle Egret and Little Egret hybrid, using observations and measurements obtained from images. The results showed that the tarsus length, the bill length, and the observed ratio of the bill length to the bill depth at the front end of the nostril of the hybrid were intermediate between those of Cattle Egret and Little Egret. There are few accounts of inter-generic hybridization among herons and egrets in nature, with only one report from Japan. This is the first record of hybridization between a Cattle Egret and a Little Egret in nature to our knowledge.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"162 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":"135110220","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}
Jorge Valenzuela Rojas, Brad A. Andres, Steven L. Garman
Many shorebirds rely on a set of key sites to complete their annual cycles at the flyway, regional, and landscape scales. Coastal wetlands on Chiloé Island, Chile, (Chiloé) support a high proportion of the Hudsonian Godwits (Limosa haemastica) spending the boreal winter along the Pacific coast of the Americas. We conducted annual counts of godwits on Chiloé between 2010 and 2020 to estimate trend in the population. To understand use of individual sites and local networks of sites (clusters), we conducted monthly counts September 2013–March 2014 and September 2017–March 2018. Because of wide variation in annual counts, we did not detect a significant trend in abundance of godwits on Chiloé. Mean monthly abundance summed across all sites during December–February varied markedly among site clusters, with godwits being most abundant in the central Chiloé cluster. Across Chiloé, variation in monthly counts of godwits at individual sites was twice as great as variation in counts summed within a cluster. Casual re-sightings of color-flagged godwits supported the idea that godwits used clusters consistently across years. Our results illustrate the importance of conserving a network of sites across multiple scales as an important step in maintaining Hudsonian Godwit populations.
{"title":"The Importance of a Network of Sites to Maintain Hudsonian Godwits (Limosa haemastica) in a Critical Non-Breeding Area","authors":"Jorge Valenzuela Rojas, Brad A. Andres, Steven L. Garman","doi":"10.1675/063.045.0403","DOIUrl":"https://doi.org/10.1675/063.045.0403","url":null,"abstract":"Many shorebirds rely on a set of key sites to complete their annual cycles at the flyway, regional, and landscape scales. Coastal wetlands on Chiloé Island, Chile, (Chiloé) support a high proportion of the Hudsonian Godwits (Limosa haemastica) spending the boreal winter along the Pacific coast of the Americas. We conducted annual counts of godwits on Chiloé between 2010 and 2020 to estimate trend in the population. To understand use of individual sites and local networks of sites (clusters), we conducted monthly counts September 2013–March 2014 and September 2017–March 2018. Because of wide variation in annual counts, we did not detect a significant trend in abundance of godwits on Chiloé. Mean monthly abundance summed across all sites during December–February varied markedly among site clusters, with godwits being most abundant in the central Chiloé cluster. Across Chiloé, variation in monthly counts of godwits at individual sites was twice as great as variation in counts summed within a cluster. Casual re-sightings of color-flagged godwits supported the idea that godwits used clusters consistently across years. Our results illustrate the importance of conserving a network of sites across multiple scales as an important step in maintaining Hudsonian Godwit populations.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"23 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":"135110223","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}
Olivia A. Morpeth, Sabrina D. Cobb, Lianne M. Koczur, Fallan Batchelor
A holistic approach to monitoring reproductive success of birds includes determining numbers of pairs, nests, chicks, and fledglings. Long-term monitoring will elucidate potential changes in the breeding population size and distribution, and possibly the causes of those changes. Further, monitoring in all stages of the reproductive cycle will help identify which stage might be limiting population growth. To assess the historical breeding populations of coastal birds in Alabama, we conducted a literature review and summarized data on reproductive metrics for American Oystercatcher (Haematopus palliatus), Black Skimmer (Rynchops niger), Least Tern (Sternula antillarum), Reddish Egret (Egretta rufescens), Snowy Plover (Charadrius nivosus), and Wilson's Plover (Charadrius wilsonia). We found 287 records from 20 sources with various metrics reported, including number of adults, pairs, nests, chicks, and fledglings, and 92 eBird records. We compared historical records to data collected during 2018–2021 to determine if and how breeding populations changed. We also compared historical and recent nesting distribution along the Alabama coast. We discuss apparent changes in breeding population sizes and potential reasons for changes in distribution, and use recent data on breeding population size and reproductive success to assess how it relates to the current conservation status of each species in Alabama.
{"title":"Coastal Bird Reproductive Metrics and Distribution in Alabama: A Review of Historical Data and Status Update","authors":"Olivia A. Morpeth, Sabrina D. Cobb, Lianne M. Koczur, Fallan Batchelor","doi":"10.1675/063.045.0404","DOIUrl":"https://doi.org/10.1675/063.045.0404","url":null,"abstract":"A holistic approach to monitoring reproductive success of birds includes determining numbers of pairs, nests, chicks, and fledglings. Long-term monitoring will elucidate potential changes in the breeding population size and distribution, and possibly the causes of those changes. Further, monitoring in all stages of the reproductive cycle will help identify which stage might be limiting population growth. To assess the historical breeding populations of coastal birds in Alabama, we conducted a literature review and summarized data on reproductive metrics for American Oystercatcher (Haematopus palliatus), Black Skimmer (Rynchops niger), Least Tern (Sternula antillarum), Reddish Egret (Egretta rufescens), Snowy Plover (Charadrius nivosus), and Wilson's Plover (Charadrius wilsonia). We found 287 records from 20 sources with various metrics reported, including number of adults, pairs, nests, chicks, and fledglings, and 92 eBird records. We compared historical records to data collected during 2018–2021 to determine if and how breeding populations changed. We also compared historical and recent nesting distribution along the Alabama coast. We discuss apparent changes in breeding population sizes and potential reasons for changes in distribution, and use recent data on breeding population size and reproductive success to assess how it relates to the current conservation status of each species in Alabama.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"29 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":"135110224","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}
Colonial nesting in seabirds is advantageous for protection from predators—spotting a predator, mobbing, and predator swamping. Familiarity with nesting areas gives knowledge of protected sites and may promote site fidelity. Familiarity with nearest neighbors helps nesting success by lessening intraspecific aggression and increasing social facilitation, and may promote group adherence. Group adherence has been proposed as more important than site tenacity for some species where nesting areas are frequently disturbed. Ground-nesting terns often nest at disturbed sites, and their colonies are accessible to predators. Serendipitously, I was able to test the concept of group adherence in individually color-marked California Least Terns Sternula antillarum browni during early egg-laying when some nests in a colony in southern California were depredated, and the adults deserted. A week later, I found the majority of those birds nesting at the edge of a small Least Tern colony 28 km distant, where they laid a second clutch and remained at the site the rest of the breeding season. The following breeding season, no color-marked terns nested again at the small colony where they had moved after disturbance.
海鸟的群体筑巢有利于保护自己免受捕食者的攻击——发现捕食者、围捕和淹没捕食者。对筑巢区域的熟悉有助于了解受保护的地点，并可能提高地点的保真度。熟悉最近的邻居有助于筑巢成功，减少种内攻击和增加社会便利，并可能促进群体的团结。对于一些筑巢区经常受到干扰的物种来说，群体粘附性比地点坚韧性更重要。地面筑巢燕鸥经常在受干扰的地方筑巢，它们的栖息地容易被捕食者接近。偶然的机会，我能够在加利福尼亚最小燕鸥(California Least Terns Sternula antillarum browni)产卵早期测试群体团结的概念，当时南加州的一个群体的一些巢穴遭到破坏，成年燕鸥被遗弃。一周后，我发现这些鸟中的大多数都在28公里外的一个小燕鸥群的边缘筑巢，在那里它们产下了第二窝，并在那里度过了繁殖季节的剩余时间。在接下来的繁殖季节，没有任何颜色的燕鸥在它们被干扰后搬到的小群体中筑巢。
{"title":"Group Adherence in Endangered California Least Terns (Sternula antillarum browni)","authors":"Patricia Baird","doi":"10.1675/063.045.0410","DOIUrl":"https://doi.org/10.1675/063.045.0410","url":null,"abstract":"Colonial nesting in seabirds is advantageous for protection from predators—spotting a predator, mobbing, and predator swamping. Familiarity with nesting areas gives knowledge of protected sites and may promote site fidelity. Familiarity with nearest neighbors helps nesting success by lessening intraspecific aggression and increasing social facilitation, and may promote group adherence. Group adherence has been proposed as more important than site tenacity for some species where nesting areas are frequently disturbed. Ground-nesting terns often nest at disturbed sites, and their colonies are accessible to predators. Serendipitously, I was able to test the concept of group adherence in individually color-marked California Least Terns Sternula antillarum browni during early egg-laying when some nests in a colony in southern California were depredated, and the adults deserted. A week later, I found the majority of those birds nesting at the edge of a small Least Tern colony 28 km distant, where they laid a second clutch and remained at the site the rest of the breeding season. The following breeding season, no color-marked terns nested again at the small colony where they had moved after disturbance.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"30 3 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":"135110222","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}
David M. Baasch, Matt Rabbe, Amanda H. Medaries, Matthew R. Schaaf, Bethany L. Ostrom, Joshua D. Wiese, Jenna M. Malzahn, Timothy J. Smith
Increases in population size and reductions in suitable migration stopover habitat associated with drought, water development, and agricultural practices, along with conspecific attraction, are hypothesized mechanisms for increasing flock sizes of migrating Whooping Cranes. During autumn 2021, we observed such a phenomenon during a period of drought in the central Great Plains when 46 Whooping Cranes gathered as a single flock in the central Platte River valley. We provide a detailed account of how this larger aggregation formed from 5 smaller groups, behavioral observations, and environmental conditions experienced during this event including river flow, ambient temperature, and wind and drought conditions. Here, we report considerations for environmental and hydrologic conditions preceding and during this event as well as use patterns and behaviors we observed while the largest single flock of Whooping Cranes ever documented in the United States portion of the migration corridor was in the central Platte River valley.
{"title":"Record-Sized Flock of Whooping Cranes (Grus americana) Observed Staging in the Central Platte River Valley During Autumn 2021","authors":"David M. Baasch, Matt Rabbe, Amanda H. Medaries, Matthew R. Schaaf, Bethany L. Ostrom, Joshua D. Wiese, Jenna M. Malzahn, Timothy J. Smith","doi":"10.1675/063.045.0413","DOIUrl":"https://doi.org/10.1675/063.045.0413","url":null,"abstract":"Increases in population size and reductions in suitable migration stopover habitat associated with drought, water development, and agricultural practices, along with conspecific attraction, are hypothesized mechanisms for increasing flock sizes of migrating Whooping Cranes. During autumn 2021, we observed such a phenomenon during a period of drought in the central Great Plains when 46 Whooping Cranes gathered as a single flock in the central Platte River valley. We provide a detailed account of how this larger aggregation formed from 5 smaller groups, behavioral observations, and environmental conditions experienced during this event including river flow, ambient temperature, and wind and drought conditions. Here, we report considerations for environmental and hydrologic conditions preceding and during this event as well as use patterns and behaviors we observed while the largest single flock of Whooping Cranes ever documented in the United States portion of the migration corridor was in the central Platte River valley.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"213 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":"135110221","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}
Hélène Sénéchal, Stéphane Lapointe, Jean-Philippe Gilbert, François Fabianek, François Bolduc
Impoundment of hydroelectric reservoirs deeply modifies habitats available for waterfowl because it involves transforming a fast-flowing river, its tributaries and nearby ponds and wetlands into a large body of water. Using a Before-After-Control-Impact design, we evaluated whether the creation of the Péribonka reservoir, a steep-sloped hydroelectric reservoir with low water level fluctuations, affected the abundance and species composition of waterfowl breeding pairs and broods in the area. We used helicopter-based waterfowl survey data covering a period of 2 years before and a period of 10 years after the creation of the reservoir. We also used 9 5x5 km plots and 72 km of river as control sites. Our results show that breeding pair density slightly increased after impoundment, while brood density increased significantly (sixfold), especially for Common Goldeneye (Bucephala clangula). This suggests that there were favorable habitat gains for waterfowl after impoundment, probably due to low water level fluctuations and localized areas of shallow water, and that mitigation measures likely helped to reduce the impact of the project. Because this BACI study ended 10 years after impoundment, it remains difficult to ascertain whether conditions in the Péribonka reservoir have stabilized or are still evolving.
{"title":"Pre- and Post-Impoundment Study of Breeding Waterfowl Use of a Hydroelectric Reservoir in the Eastern Canadian Boreal Forest","authors":"Hélène Sénéchal, Stéphane Lapointe, Jean-Philippe Gilbert, François Fabianek, François Bolduc","doi":"10.1675/063.045.0405","DOIUrl":"https://doi.org/10.1675/063.045.0405","url":null,"abstract":"Impoundment of hydroelectric reservoirs deeply modifies habitats available for waterfowl because it involves transforming a fast-flowing river, its tributaries and nearby ponds and wetlands into a large body of water. Using a Before-After-Control-Impact design, we evaluated whether the creation of the Péribonka reservoir, a steep-sloped hydroelectric reservoir with low water level fluctuations, affected the abundance and species composition of waterfowl breeding pairs and broods in the area. We used helicopter-based waterfowl survey data covering a period of 2 years before and a period of 10 years after the creation of the reservoir. We also used 9 5x5 km plots and 72 km of river as control sites. Our results show that breeding pair density slightly increased after impoundment, while brood density increased significantly (sixfold), especially for Common Goldeneye (Bucephala clangula). This suggests that there were favorable habitat gains for waterfowl after impoundment, probably due to low water level fluctuations and localized areas of shallow water, and that mitigation measures likely helped to reduce the impact of the project. Because this BACI study ended 10 years after impoundment, it remains difficult to ascertain whether conditions in the Péribonka reservoir have stabilized or are still evolving.","PeriodicalId":54408,"journal":{"name":"Waterbirds","volume":"113 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":"135109993","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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