J. Waldenström, Mariëlle L. van Toor, Å. Lindström
The Little Stint Calidris minuta is an Arctic wader species that migrates through the Baltic Sea region towards wintering areas in North and West Africa and the Mediterranean region. We use a 75-year trapping series, comprising 4,791 Little Stints on autumn migration, from Ottenby Bird Observatory in Sweden to illustrate long-term trends in abundance, phenology, and morphometrics. Numbers of trapped juveniles dropped from median 31 (mean 74) in 1946–1999 to median 1.5 (mean 3.5) birds in 2000–2020, while the number of adults was generally low and without trends. Rolling window analyses showed that the drop in juveniles started around 1984, and from 1993 onward the median never exceeded seven juveniles/year (25 %-quantile: 0–1; 75 %-quantile: 4–55). Moreover, adult birds advanced their passage on average 0.48 days per year, passing 26 days earlier in 2020 than in 1946. Earlier migration of adults and decreased numbers of juveniles suggest low reproductive output in recent decades. Morphometric data of recaptured birds show that Little Stints on stopover at Ottenby gain fuel at a speed close to the theoretical maximum, strongly indicating that the conditions at the trapping site remain favourable for foraging waders.
{"title":"Long-term trends in abundance, phenology, and morphometrics of Little Stint Calidris minuta during autumn migration in southern Sweden, 1946–2020","authors":"J. Waldenström, Mariëlle L. van Toor, Å. Lindström","doi":"10.34080/os.v33.23489","DOIUrl":"https://doi.org/10.34080/os.v33.23489","url":null,"abstract":"The Little Stint Calidris minuta is an Arctic wader species that migrates through the Baltic Sea region towards wintering areas in North and West Africa and the Mediterranean region. We use a 75-year trapping series, comprising 4,791 Little Stints on autumn migration, from Ottenby Bird Observatory in Sweden to illustrate long-term trends in abundance, phenology, and morphometrics. Numbers of trapped juveniles dropped from median 31 (mean 74) in 1946–1999 to median 1.5 (mean 3.5) birds in 2000–2020, while the number of adults was generally low and without trends. Rolling window analyses showed that the drop in juveniles started around 1984, and from 1993 onward the median never exceeded seven juveniles/year (25 %-quantile: 0–1; 75 %-quantile: 4–55). Moreover, adult birds advanced their passage on average 0.48 days per year, passing 26 days earlier in 2020 than in 1946. Earlier migration of adults and decreased numbers of juveniles suggest low reproductive output in recent decades. Morphometric data of recaptured birds show that Little Stints on stopover at Ottenby gain fuel at a speed close to the theoretical maximum, strongly indicating that the conditions at the trapping site remain favourable for foraging waders.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48233303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nest site features and habitats of the White-tailed Eagle Haliaeetus albicilla were studied in Gotland, Sweden, during 2008–2017. Here, the entire population depended on suitable trees for nesting. The mean age of the nesting trees was 173 years. Only 9% of these trees were younger than 125 years. The mean distance from nests to roads was 400 metres. The mean distance to permanent residences and recreational cottages was 1.5 km and 1.2 km, respectively. Although the nests were not located far from human activities, the eagles were very shy. Therefore, they need protected areas around the nesting trees, especially during the breeding season.
{"title":"Häckningsbiotop och boplatsval hos havsörn Haliaeetus albicilla på Gotland","authors":"Lars-Erik Wiss","doi":"10.34080/os.v33.23485","DOIUrl":"https://doi.org/10.34080/os.v33.23485","url":null,"abstract":"Nest site features and habitats of the White-tailed Eagle Haliaeetus albicilla were studied in Gotland, Sweden, during 2008–2017. Here, the entire population depended on suitable trees for nesting. The mean age of the nesting trees was 173 years. Only 9% of these trees were younger than 125 years. The mean distance from nests to roads was 400 metres. The mean distance to permanent residences and recreational cottages was 1.5 km and 1.2 km, respectively. Although the nests were not located far from human activities, the eagles were very shy. Therefore, they need protected areas around the nesting trees, especially during the breeding season. ","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45298425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The West Siberian/North European population of Long-tailed Duck Clangula hyemalis that breeds in Fennoscandia and Northwestern Russia, and winters in the Baltic Sea, has declined by at least 65% since the 1990s and is classified as globally vulnerable. To propose effective management actions to stop the decline, knowledge about demographic parameters is required. A photo survey method by which it is possible, in winter, to collect data on sex ratios and production of first-winter birds is presented here. The plumage traits and bill patterns, which are detectable in photos taken at a distance, are described. The traits can be used to discriminate between three categories of birds: adult males, first-winter males, and females. To extrapolate results from several photo surveys and obtain population-wide estimates of demographic parameters, knowledge about non-random distributions of different bird categories is needed. It was found that different age and sex categories were distributed differently across flocks of different sizes. The required sample sizes and the possible constraints and biases related to the photo survey method are discussed.
{"title":"Age and sex ratios of wintering Long-tailed Ducks Clangula hyemalis can be determined by analysis of photos of flying flocks at sea: A method description","authors":"K. Larsson","doi":"10.34080/os.v33.23757","DOIUrl":"https://doi.org/10.34080/os.v33.23757","url":null,"abstract":"The West Siberian/North European population of Long-tailed Duck Clangula hyemalis that breeds in Fennoscandia and Northwestern Russia, and winters in the Baltic Sea, has declined by at least 65% since the 1990s and is classified as globally vulnerable. To propose effective management actions to stop the decline, knowledge about demographic parameters is required. A photo survey method by which it is possible, in winter, to collect data on sex ratios and production of first-winter birds is presented here. The plumage traits and bill patterns, which are detectable in photos taken at a distance, are described. The traits can be used to discriminate between three categories of birds: adult males, first-winter males, and females. To extrapolate results from several photo surveys and obtain population-wide estimates of demographic parameters, knowledge about non-random distributions of different bird categories is needed. It was found that different age and sex categories were distributed differently across flocks of different sizes. The required sample sizes and the possible constraints and biases related to the photo survey method are discussed.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49206536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Razorbill Alca torda is one of three auk species breeding in Sweden, often occurring in colonies with Common Guillemot Uria aalge. The largest colony in the Baltic Sea is situated on the island Stora Karlsö west of Gotland. During the chick-rearing phase, Razorbills forage at sea and return to feed the young with single or multiple prey carried sideways in the bill, unlike Common Guillemots that carry a single fish in the middle of the bill. Clupeids, especially sprat Sprattus sprattus, are the main prey of Baltic Sea Razorbills, but studies are scarce. Here, we investigate the diet preference of Razorbills at Stora Karlsö with regard to prey taxonomy and size, analysing photographs and applying morphometric equations. We show that most feeding attempts involved a single clupeid (88% of known fish taxonomy), in most cases likely sprat. The average prey size (115 mm) and prey species was similar to that of Common Guillemots in the same colony. The variation in size was much smaller in the Razorbill diet than the size distribution of clupeids at sea, indicating a strong prey size selectivity. The Razorbills’ high specialisation underlines the importance of maintaining strong populations of clupeids in their foraging area, as these fish are also targeted by industrial fisheries.
{"title":"Diet and prey size preference in Razorbills Alca torda breeding at Stora Karlsö, Sweden","authors":"E. Engvall, J. Waldenström, J. Hentati‐Sundberg","doi":"10.34080/os.v32.22615","DOIUrl":"https://doi.org/10.34080/os.v32.22615","url":null,"abstract":"The Razorbill Alca torda is one of three auk species breeding in Sweden, often occurring in colonies with Common Guillemot Uria aalge. The largest colony in the Baltic Sea is situated on the island Stora Karlsö west of Gotland. During the chick-rearing phase, Razorbills forage at sea and return to feed the young with single or multiple prey carried sideways in the bill, unlike Common Guillemots that carry a single fish in the middle of the bill. Clupeids, especially sprat Sprattus sprattus, are the main prey of Baltic Sea Razorbills, but studies are scarce. Here, we investigate the diet preference of Razorbills at Stora Karlsö with regard to prey taxonomy and size, analysing photographs and applying morphometric equations. We show that most feeding attempts involved a single clupeid (88% of known fish taxonomy), in most cases likely sprat. The average prey size (115 mm) and prey species was similar to that of Common Guillemots in the same colony. The variation in size was much smaller in the Razorbill diet than the size distribution of clupeids at sea, indicating a strong prey size selectivity. The Razorbills’ high specialisation underlines the importance of maintaining strong populations of clupeids in their foraging area, as these fish are also targeted by industrial fisheries.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49183489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A first-winter male hybrid Common Redstart Phoenicurus phoenicurus × Black Redstart P. ochrurus was trapped, ringed, photographed and sound recorded at Ottenby Bird Observatory, SE Sweden. Hybrid redstarts are rare but regularly encountered in Europe, but most observations concern birds in worn breeding plumage during spring and summer. This bird appears to be the first record for Sweden of an autumn bird in fresh post-juvenile plumage.
在瑞典东南部的Ottenby鸟类观测站，捕获了一只首次冬季雄性杂交的普通红start Phoenicurus Phoenicurus和黑红start P. ochrurus。杂交红雀很少见，但在欧洲经常遇到，但大多数观察都是在春夏季节，鸟类的繁殖羽毛磨损。这只鸟似乎是瑞典的第一个记录，一只秋天的鸟在年轻后的新鲜羽毛。
{"title":"A rare case of a first-winter male hybrid Common Redstart Phoenicurus phoenicurus × Black Redstart P. ochruros ringed at Ottenby, Sweden","authors":"Magnus Hellström","doi":"10.34080/os.v32.23819","DOIUrl":"https://doi.org/10.34080/os.v32.23819","url":null,"abstract":"A first-winter male hybrid Common Redstart Phoenicurus phoenicurus × Black Redstart P. ochrurus was trapped, ringed, photographed and sound recorded at Ottenby Bird Observatory, SE Sweden. Hybrid redstarts are rare but regularly encountered in Europe, but most observations concern birds in worn breeding plumage during spring and summer. This bird appears to be the first record for Sweden of an autumn bird in fresh post-juvenile plumage.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42431011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Black Redstart Phoenicurus ochruros immigrated to Sweden around the turn of the last century, however the great wave of expansion took place from the late 1940s until the 1980s. The early expansion was considered to mainly comprise inexperienced young birds, which extended their spring migration and pioneered the northern areas. In this studyI investigate the proportion of first-year singing males in Swedish populations and compare this with data from core areas in Germany and Austria. The proportion of first-year singing males was around 50% in all of the populations, in Sweden as well as in central Europe. However, only a few first-year males return to the Swedish natal area. Perhaps the similar age distribution between the populations indicates an apparent stability in age structure in the Swedish populations. In addition to the territorial males in western Sweden, there are sporadically occurring individuals, which have been attributed to a so-called floating population. Whether the current turnover of young birds in Sweden originates from continental populations, or more nearby areas in Scandinavia, is unknown.
{"title":"Andelen ettåriga hannar i svenska populationer av svart rödstjärt Phoenicurus ochruros","authors":"Reino Andersson","doi":"10.34080/os.v32.23817","DOIUrl":"https://doi.org/10.34080/os.v32.23817","url":null,"abstract":"The Black Redstart Phoenicurus ochruros immigrated to Sweden around the turn of the last century, however the great wave of expansion took place from the late 1940s until the 1980s. The early expansion was considered to mainly comprise inexperienced young birds, which extended their spring migration and pioneered the northern areas. In this studyI investigate the proportion of first-year singing males in Swedish populations and compare this with data from core areas in Germany and Austria. The proportion of first-year singing males was around 50% in all of the populations, in Sweden as well as in central Europe. However, only a few first-year males return to the Swedish natal area. Perhaps the similar age distribution between the populations indicates an apparent stability in age structure in the Swedish populations. In addition to the territorial males in western Sweden, there are sporadically occurring individuals, which have been attributed to a so-called floating population. Whether the current turnover of young birds in Sweden originates from continental populations, or more nearby areas in Scandinavia, is unknown.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48283766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marcin Przymencki, Klaudia Litwiniak, N. Atamas, M. Krukowski
Measuring nest size is an important aspect of studying the breeding biology of birds. Although some simple equations for estimating the volume of passerine nests are available, no methods to estimate nest size for gulls have been described. This paper offers an equation for calculating the volume of gull nests, based on the truncated cone. It requires only four measurements of the nest: outer diameter, inner diameter, height, and cup depth. We also present a way of estimating the volume of nest material.
{"title":"A method to estimate the volume of gull nests","authors":"Marcin Przymencki, Klaudia Litwiniak, N. Atamas, M. Krukowski","doi":"10.34080/os.v32.23442","DOIUrl":"https://doi.org/10.34080/os.v32.23442","url":null,"abstract":"Measuring nest size is an important aspect of studying the breeding biology of birds. Although some simple equations for estimating the volume of passerine nests are available, no methods to estimate nest size for gulls have been described. This paper offers an equation for calculating the volume of gull nests, based on the truncated cone. It requires only four measurements of the nest: outer diameter, inner diameter, height, and cup depth. We also present a way of estimating the volume of nest material.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46363900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Antti Tanskanen, R. Yrjölä, Johanna Oja, Risto Aalto, Sakari Tanskanen
Breeding bird populations were monitored at a wind farm in the Båtskär area of the southern Åland archipelago in 2006–2017. The area is situated in the outer archipelago and comprises four islands with six wind turbines in total. The wind turbines began operating in autumn 2007. An environmental impact assessment for the area was conducted in 2002. A control area called Stenarna, located 22 km NW of Båtskär, was used for comparison. The Båtskär area annually recorded 850–1,050 pairs of breeding birds. Four species showed significantly decreasing trends in Båtskär, namely the Common Eider Somateria mollissima, Lesser Black-backed Gull Larus fuscus, Herring Gull L. argentatus , and Black Guillemot Cepphus grylle. In Stenarna, only the Common Eider significantly decreased over the same period. The Arctic Tern Sterna paradisaea increased in both areas, while the Velvet Scoter Melanitta fusca, Red-breasted Merganser Mergus serrator, Common Gull Larus canus, Rock Pipit Anthus petrosus, and White Wagtail Motacilla alba increased in Stenarna, the control area. The Herring Gull population decline is unlikely to be related to the wind farm. However, the proximity of a wind turbine to a breeding colony of the Lesser Black-backed Gull has most likely contributed to its decline. The reason for the Black Guillemot decline in Båtskär is unknown. The decline of Common Eider in both areas may be connected to increasing predation from White-tailed Eagles Haliaeetus albicilla. Some species, such as the House Martin Delichon urbicum and auks, have benefitted from the wind farm construction. They can utilize new microhabitats created by the construction, while other species, such as the Common Eider, gain protection against predation because of human activities.
{"title":"Long-term impact on the breeding birds of a semi-offshore island-based wind farm in Åland, Northern Baltic Sea","authors":"Antti Tanskanen, R. Yrjölä, Johanna Oja, Risto Aalto, Sakari Tanskanen","doi":"10.34080/os.v32.22331","DOIUrl":"https://doi.org/10.34080/os.v32.22331","url":null,"abstract":"Breeding bird populations were monitored at a wind farm in the Båtskär area of the southern Åland archipelago in 2006–2017. The area is situated in the outer archipelago and comprises four islands with six wind turbines in total. The wind turbines began operating in autumn 2007. An environmental impact assessment for the area was conducted in 2002. A control area called Stenarna, located 22 km NW of Båtskär, was used for comparison. The Båtskär area annually recorded 850–1,050 pairs of breeding birds. Four species showed significantly decreasing trends in Båtskär, namely the Common Eider Somateria mollissima, Lesser Black-backed Gull Larus fuscus, Herring Gull L. argentatus , and Black Guillemot Cepphus grylle. In Stenarna, only the Common Eider significantly decreased over the same period. The Arctic Tern Sterna paradisaea increased in both areas, while the Velvet Scoter Melanitta fusca, Red-breasted Merganser Mergus serrator, Common Gull Larus canus, Rock Pipit Anthus petrosus, and White Wagtail Motacilla alba increased in Stenarna, the control area. The Herring Gull population decline is unlikely to be related to the wind farm. However, the proximity of a wind turbine to a breeding colony of the Lesser Black-backed Gull has most likely contributed to its decline. The reason for the Black Guillemot decline in Båtskär is unknown. The decline of Common Eider in both areas may be connected to increasing predation from White-tailed Eagles Haliaeetus albicilla. Some species, such as the House Martin Delichon urbicum and auks, have benefitted from the wind farm construction. They can utilize new microhabitats created by the construction, while other species, such as the Common Eider, gain protection against predation because of human activities.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44415624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Territory-holding male Willow Warblers Phylloscopus trochilus stood on one leg when they were singing at song posts for extended periods of time. The other leg was tucked in the breast plumage and not visible. The length of time spent on a twig was positively correlated to the use of unipedal stance. Observed birds spent longer pose time perched on one leg than on two legs. The right leg and the left leg were used at similar frequencies. The reason for this behaviour might be to save energy, by reducing heat loss through the skin of the tucked leg.
{"title":"An examination of perched Willow Warblers Phylloscopus trochilus singing on one leg","authors":"K. Nyström","doi":"10.34080/os.v32.22447","DOIUrl":"https://doi.org/10.34080/os.v32.22447","url":null,"abstract":"Territory-holding male Willow Warblers Phylloscopus trochilus stood on one leg when they were singing at song posts for extended periods of time. The other leg was tucked in the breast plumage and not visible. The length of time spent on a twig was positively correlated to the use of unipedal stance. Observed birds spent longer pose time perched on one leg than on two legs. The right leg and the left leg were used at similar frequencies. The reason for this behaviour might be to save energy, by reducing heat loss through the skin of the tucked leg.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46427243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
U. Lötberg, N. Isaksson, Lennart Söderlund, S. Åkesson
We present conservation actions during 2007–2020 as part of the national Caspian Tern Hydroprogne caspia species action plan at Stenarna in the Björn archipelago, Uppland, the largest colony in Sweden. We applied a combination of monitoring, research, and management measures conducted within an adaptive approach framework, using both established and novel techniques. The implementation of conservation measures led to increased breeding success, from 0 fledglings per pair in 2007 to 1.3 in 2020. A surveillance video camera installed in 2009 aided in monitoring efforts and also revealed predation by Herring Gull Larus argentatus and White-tailed Eagle Haliaeetus albicilla, leading to species-specific control strategies. Management of the island and surrounding archipelago, including hunting of invasive American mink Mustela vison, vegetation removal, and habitat restoration after a severe storm, have also been instrumental to the success of the project. Implementation of projects such as this have the potential to improve conditions for continued viability of endangered species in a changing world and are likely to be useful to other conservation practitioners.
{"title":"Conservation measures for the Caspian Tern Hydroprogne caspia at the largest colony in Sweden","authors":"U. Lötberg, N. Isaksson, Lennart Söderlund, S. Åkesson","doi":"10.34080/os.v32.22569","DOIUrl":"https://doi.org/10.34080/os.v32.22569","url":null,"abstract":"We present conservation actions during 2007–2020 as part of the national Caspian Tern Hydroprogne caspia species action plan at Stenarna in the Björn archipelago, Uppland, the largest colony in Sweden. We applied a combination of monitoring, research, and management measures conducted within an adaptive approach framework, using both established and novel techniques. The implementation of conservation measures led to increased breeding success, from 0 fledglings per pair in 2007 to 1.3 in 2020. A surveillance video camera installed in 2009 aided in monitoring efforts and also revealed predation by Herring Gull Larus argentatus and White-tailed Eagle Haliaeetus albicilla, leading to species-specific control strategies. Management of the island and surrounding archipelago, including hunting of invasive American mink Mustela vison, vegetation removal, and habitat restoration after a severe storm, have also been instrumental to the success of the project. Implementation of projects such as this have the potential to improve conditions for continued viability of endangered species in a changing world and are likely to be useful to other conservation practitioners.","PeriodicalId":52418,"journal":{"name":"Ornis Svecica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48143851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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