Pub Date : 2024-02-06DOI: 10.1093/ornithapp/duae006
Florencia M Pucheta, Inés M Pereda, Adrián S Di Giacomo
The Saffron-cowled Blackbird (Xanthopsar flavus) is a globally endangered icterid endemic to the southern South American grasslands. Temperate grasslands are among the most threatened ecosystems in South America due to their high rate of land use change. In northeastern Argentina, over the last century, the conversion of natural grasslands to livestock farming, croplands, and afforestation have resulted in significant losses of breeding habitat for the Saffron-cowled Blackbird. Consequently, it has suffered severe populational declines, and its remaining populations are fragmented. In order to understand the impact of agricultural systems on the Saffron-cowled Blackbird populations, we studied its breeding biology (clutch size, hatching success, nestling production, and fledgling success) and the main parameters that influence nest survival rate in five breeding habitat types. During the breeding seasons of 2015 to 2019, we located nests and monitored their fate. We found that the cumulative probability of nest survival over the entire nesting cycle (i.e., laying, incubation, and chick rearing) was 0.06, and was lower for nests situated in grazed land covers. Conversely, nest survival was greater in breeding sites without agricultural use, particularly in marshes. Predation was the main cause of nest failure (76%), followed by brood parasitism (10%), and trampling by cattle and agricultural machinery (6%). Brood parasitism rates were higher in grazed paddocks, contributing together with predation to the failure of nests in this habitat. Our findings indicate a negative impact of livestock ranching on Saffron-cowled Blackbird reproduction. Non-agriculture habitats, like wetlands and flooded areas, are important as refuges for nesting. Thus, the creation of breeding refuges (non-productive sites) within agricultural matrices, in association with biodiversity-friendly agricultural practices, is crucial to ensure the Saffron-cowled Blackbird’s maintenance.
{"title":"Saffron-cowled Blackbirds reduced nest success in Argentina’s agricultural land highlights the importance of non-agricultural habitat for its conservation","authors":"Florencia M Pucheta, Inés M Pereda, Adrián S Di Giacomo","doi":"10.1093/ornithapp/duae006","DOIUrl":"https://doi.org/10.1093/ornithapp/duae006","url":null,"abstract":"The Saffron-cowled Blackbird (Xanthopsar flavus) is a globally endangered icterid endemic to the southern South American grasslands. Temperate grasslands are among the most threatened ecosystems in South America due to their high rate of land use change. In northeastern Argentina, over the last century, the conversion of natural grasslands to livestock farming, croplands, and afforestation have resulted in significant losses of breeding habitat for the Saffron-cowled Blackbird. Consequently, it has suffered severe populational declines, and its remaining populations are fragmented. In order to understand the impact of agricultural systems on the Saffron-cowled Blackbird populations, we studied its breeding biology (clutch size, hatching success, nestling production, and fledgling success) and the main parameters that influence nest survival rate in five breeding habitat types. During the breeding seasons of 2015 to 2019, we located nests and monitored their fate. We found that the cumulative probability of nest survival over the entire nesting cycle (i.e., laying, incubation, and chick rearing) was 0.06, and was lower for nests situated in grazed land covers. Conversely, nest survival was greater in breeding sites without agricultural use, particularly in marshes. Predation was the main cause of nest failure (76%), followed by brood parasitism (10%), and trampling by cattle and agricultural machinery (6%). Brood parasitism rates were higher in grazed paddocks, contributing together with predation to the failure of nests in this habitat. Our findings indicate a negative impact of livestock ranching on Saffron-cowled Blackbird reproduction. Non-agriculture habitats, like wetlands and flooded areas, are important as refuges for nesting. Thus, the creation of breeding refuges (non-productive sites) within agricultural matrices, in association with biodiversity-friendly agricultural practices, is crucial to ensure the Saffron-cowled Blackbird’s maintenance.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764973","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}
Pub Date : 2024-01-31DOI: 10.1093/ornithapp/duae002
Esteban Botero-Delgadillo, Enrick Meza-Angulo, Nicholas J Bayly
Abundance measures are almost non-existent for several bird species threatened with extinction, particularly range-restricted Neotropical taxa, for which estimating population sizes can be challenging. Here we use data collected over 9 years to explore the abundance of 11 endemic birds from the Sierra Nevada de Santa Marta (SNSM), one of Earth’s most irreplaceable ecosystems. We established 99 transects in the “Cuchilla de San Lorenzo” Important Bird Area within native forest, early successional vegetation, and areas of transformed vegetation by human activities. A total of 763 bird counts were carried out covering the entire elevation range in the study area (~175–2,650 m). We applied hierarchical distance-sampling models to assess elevation- and habitat-related variation in local abundance and obtain values of population density and total and effective population size. Most species were more abundant in the montane elevational range (1,800–2,650 m). Habitat-related differences in abundance were only detected for 5 species, which were more numerous in either early succession, secondary forest, or transformed areas. Inferences of effective population size indicated that at least 4 endemics likely maintain populations no larger than 15,000–20,000 mature individuals. Estimates of species’ area of occupancy and effective population size were lower than most values previously described, a possible consequence of increasing anthropogenic threats. At least 4 of the endemics exceeded criteria for threatened species listing and a thorough evaluation of their extinction risk should be conducted. Population strongholds for most of the study species were located on the northern and western slopes of the SNSM between 1,500 and 2,700 m. We highlight the urgent need for facilitating effective protection of native vegetation in premontane and montane ecosystems to safeguard critical habitats for the SNSM’s endemic avifauna. Follow-up studies collecting abundance data across the SNSM are needed to obtain precise range-wide density estimations for all species.
对于一些濒临灭绝的鸟类物种，尤其是受分布范围限制的新热带类群，几乎不存在丰度测量方法，因此估算种群数量具有挑战性。在此，我们利用历时 9 年收集的数据，对地球上最不可替代的生态系统之一--圣玛尔塔内华达山脉（Sierra Nevada de Santa Marta，SNSM）的 11 种特有鸟类的丰度进行了研究。我们在 "Cuchilla de San Lorenzo "重要鸟类区的原始森林、早期演替植被以及因人类活动而改变植被的区域内建立了 99 个横断面。我们共进行了 763 次鸟类计数，覆盖了研究区的整个海拔范围（约 175-2,650 米）。我们采用分层距离抽样模型来评估与海拔和栖息地有关的当地丰度变化，并获得种群密度、总种群数量和有效种群数量的数值。大多数物种在山地海拔范围（1,800-2,650 米）内更为丰富。只有 5 个物种的丰度与生境有关，它们在早期演替区、次生林或改造区的数量较多。对有效种群规模的推断表明，至少有 4 种特有物种的成熟个体数量可能不超过 15,000-20,000 个。物种栖息地面积和有效种群数量的估计值低于之前描述的大多数值，这可能是人类活动威胁不断增加的结果。至少有 4 种特有物种超过了列入濒危物种的标准，因此应对其灭绝风险进行全面评估。大多数研究物种的种群据点都位于海拔1500米至2700米之间的国家南极海洋生物资源保护区北部和西部山坡上。需要开展后续研究，收集整个南极海洋生态系统的丰度数据，以获得所有物种在整个分布区的精确密度估算。
{"title":"Abundance models of endemic birds of the Sierra Nevada de Santa Marta, northern South America, suggest small population sizes and dependence on montane elevations","authors":"Esteban Botero-Delgadillo, Enrick Meza-Angulo, Nicholas J Bayly","doi":"10.1093/ornithapp/duae002","DOIUrl":"https://doi.org/10.1093/ornithapp/duae002","url":null,"abstract":"Abundance measures are almost non-existent for several bird species threatened with extinction, particularly range-restricted Neotropical taxa, for which estimating population sizes can be challenging. Here we use data collected over 9 years to explore the abundance of 11 endemic birds from the Sierra Nevada de Santa Marta (SNSM), one of Earth’s most irreplaceable ecosystems. We established 99 transects in the “Cuchilla de San Lorenzo” Important Bird Area within native forest, early successional vegetation, and areas of transformed vegetation by human activities. A total of 763 bird counts were carried out covering the entire elevation range in the study area (~175–2,650 m). We applied hierarchical distance-sampling models to assess elevation- and habitat-related variation in local abundance and obtain values of population density and total and effective population size. Most species were more abundant in the montane elevational range (1,800–2,650 m). Habitat-related differences in abundance were only detected for 5 species, which were more numerous in either early succession, secondary forest, or transformed areas. Inferences of effective population size indicated that at least 4 endemics likely maintain populations no larger than 15,000–20,000 mature individuals. Estimates of species’ area of occupancy and effective population size were lower than most values previously described, a possible consequence of increasing anthropogenic threats. At least 4 of the endemics exceeded criteria for threatened species listing and a thorough evaluation of their extinction risk should be conducted. Population strongholds for most of the study species were located on the northern and western slopes of the SNSM between 1,500 and 2,700 m. We highlight the urgent need for facilitating effective protection of native vegetation in premontane and montane ecosystems to safeguard critical habitats for the SNSM’s endemic avifauna. Follow-up studies collecting abundance data across the SNSM are needed to obtain precise range-wide density estimations for all species.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"409 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139658742","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}
Pub Date : 2024-01-30DOI: 10.1093/ornithapp/duae005
Tomohiro Deguchi, Yuji Okahisa, Yoshito Ohsako
Long-lived territorial bird populations often consist of a few territorial breeding adults and many nonbreeding individuals. Some populations are threatened by anthropogenic activities, because of human conflicts for high-quality breeding habitat. Therefore, habitat restoration projects have been widely implemented to improve avian population status. In conjunction with habitat restoration, conservation translocations have been increasingly implemented. Adequate nonbreeder survival can be a key factor in the success of these attempts because nonbreeding birds may represent reservoirs for the replacement of breeders. The maintenance of breeding pair numbers is also influenced by the transition rate of nonbreeders to breeders. The reintroduction of Oriental Stork (Ciconia boyciana), a long-lived, territorial, endangered species, was initiated in Japan in 2005 using captive birds in hopes of increasing the population’s use of restored habitat. Our objective of this study was to elucidate the factors determining reintroduced stork survival and recruitment to the breeding populations. We estimated the survival rate and breeding participation rate by sex, age, generation, wild-born or not, haplotypes, and breeding status in storks reintroduced during 2005–2022 using Bayesian hierarchical models. There was no significant difference in survival rate between nonbreeders and breeders. However, the survival rate was lower in wild-born birds than released birds, which may be related to the longer-distance natal dispersal of new generations. Accelerated habitat restoration around breeding areas and preventive measures for collision with human-built structures should be implemented for the sustained growth of reintroduced populations. A low survival rate was also detected for a specific mitochondrial DNA (mtDNA) haplotype that accounts for the majority of the reintroduced population. This phenomenon might be explained by mtDNA-encoded mutations. Moreover, captive breeding and release history might contribute to an increase in the proportion of this haplotype in the wild.
{"title":"Reintroduced Oriental Stork survival differed by mitochondrial DNA haplotype","authors":"Tomohiro Deguchi, Yuji Okahisa, Yoshito Ohsako","doi":"10.1093/ornithapp/duae005","DOIUrl":"https://doi.org/10.1093/ornithapp/duae005","url":null,"abstract":"Long-lived territorial bird populations often consist of a few territorial breeding adults and many nonbreeding individuals. Some populations are threatened by anthropogenic activities, because of human conflicts for high-quality breeding habitat. Therefore, habitat restoration projects have been widely implemented to improve avian population status. In conjunction with habitat restoration, conservation translocations have been increasingly implemented. Adequate nonbreeder survival can be a key factor in the success of these attempts because nonbreeding birds may represent reservoirs for the replacement of breeders. The maintenance of breeding pair numbers is also influenced by the transition rate of nonbreeders to breeders. The reintroduction of Oriental Stork (Ciconia boyciana), a long-lived, territorial, endangered species, was initiated in Japan in 2005 using captive birds in hopes of increasing the population’s use of restored habitat. Our objective of this study was to elucidate the factors determining reintroduced stork survival and recruitment to the breeding populations. We estimated the survival rate and breeding participation rate by sex, age, generation, wild-born or not, haplotypes, and breeding status in storks reintroduced during 2005–2022 using Bayesian hierarchical models. There was no significant difference in survival rate between nonbreeders and breeders. However, the survival rate was lower in wild-born birds than released birds, which may be related to the longer-distance natal dispersal of new generations. Accelerated habitat restoration around breeding areas and preventive measures for collision with human-built structures should be implemented for the sustained growth of reintroduced populations. A low survival rate was also detected for a specific mitochondrial DNA (mtDNA) haplotype that accounts for the majority of the reintroduced population. This phenomenon might be explained by mtDNA-encoded mutations. Moreover, captive breeding and release history might contribute to an increase in the proportion of this haplotype in the wild.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"86 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139649273","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}
Pub Date : 2024-01-30DOI: 10.1093/ornithapp/duae004
Asaf Mayrose, Eli Haviv, Ohad Hatzofe, David Troupin, Michal Elroy, Nir Sapir
The Bonelli’s Eagle (Aquila fasciata) is a critically endangered species in Israel, with electrocution on power lines posing a serious threat to its population. Because retrofitting of electricity pylons to prevent mortality is a slow and costly process, it is important to prioritize the pylons in the network for quick and efficient mitigation of eagle mortality. To determine which pylons need to be retrofitted, we applied a three-stage maximum entropy modeling process for identifying the risk factors posed by different environmental variables. The environmental feature with the highest correlation to electrocution is the distance to reservoirs (i.e., many electrocution events occur near water reservoirs). The reservoirs are foraging hotspots for Bonelli’s Eagles in Israel’s arid environment. Electricity pylons powering the reservoirs’ pumping facilities tend to be the highest perches in the vicinity of many of the reservoirs, creating an ecological trap. The strong attraction of reservoirs to eagles may explain the high level of selectivity indicated by the model, suggesting that retrofitting only 3.6% of the pylons in the network would achieve 77% reduction in eagles’ electrocution probability. Moreover, insulating pylons according to the model will also likely reduce electrocutions of other avian species, including Eastern Imperial Eagle (Aquila heliaca) and White-tailed Eagle (Haliaeetus albicilla). The modeling process presented here yielded two electrocution risk maps, one to facilitate prioritization of mitigation in Israel’s existing power network and the second to support planning and designing new infrastructure. The model may help reach conservation goals for Bonelli’s Eagle and may also be useful in prioritizing pylon retrofitting in other arid landscapes.
{"title":"Bonelli’s Eagle electrocution risk in Israel can be reduced by 80% by insulating only 4% of the pylons","authors":"Asaf Mayrose, Eli Haviv, Ohad Hatzofe, David Troupin, Michal Elroy, Nir Sapir","doi":"10.1093/ornithapp/duae004","DOIUrl":"https://doi.org/10.1093/ornithapp/duae004","url":null,"abstract":"The Bonelli’s Eagle (Aquila fasciata) is a critically endangered species in Israel, with electrocution on power lines posing a serious threat to its population. Because retrofitting of electricity pylons to prevent mortality is a slow and costly process, it is important to prioritize the pylons in the network for quick and efficient mitigation of eagle mortality. To determine which pylons need to be retrofitted, we applied a three-stage maximum entropy modeling process for identifying the risk factors posed by different environmental variables. The environmental feature with the highest correlation to electrocution is the distance to reservoirs (i.e., many electrocution events occur near water reservoirs). The reservoirs are foraging hotspots for Bonelli’s Eagles in Israel’s arid environment. Electricity pylons powering the reservoirs’ pumping facilities tend to be the highest perches in the vicinity of many of the reservoirs, creating an ecological trap. The strong attraction of reservoirs to eagles may explain the high level of selectivity indicated by the model, suggesting that retrofitting only 3.6% of the pylons in the network would achieve 77% reduction in eagles’ electrocution probability. Moreover, insulating pylons according to the model will also likely reduce electrocutions of other avian species, including Eastern Imperial Eagle (Aquila heliaca) and White-tailed Eagle (Haliaeetus albicilla). The modeling process presented here yielded two electrocution risk maps, one to facilitate prioritization of mitigation in Israel’s existing power network and the second to support planning and designing new infrastructure. The model may help reach conservation goals for Bonelli’s Eagle and may also be useful in prioritizing pylon retrofitting in other arid landscapes.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"88 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139646361","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}
Pub Date : 2024-01-29DOI: 10.1093/ornithapp/duae003
Abigail J Darrah
Coastal birds that rely on sandy beaches for breeding are vulnerable to catastrophic flooding events resulting from tropical cyclones. The effects of storm surge on annual productivity depend on the propensity and success of renesting attempts post-storm. From 2017 to 2021, I investigated the effects of storm surge on Least Tern (Sternula antillarum) annual productivity, renesting probability, and nest and chick survival after storms on Mississippi’s Gulf of Mexico Coast. Tropical cyclones made landfall during peak breeding period in 3 of these years, resulting in complete overwash of all colonies. Observers monitored daily nest survival, productivity (maximum fledge count per maximum nest count), and frequency of disturbance from avian predators at each colony. Total annual productivity (fledge count per nest count across the study area) summed across colonies ranged from 0.00 to 0.07 in storm years and from 0.29 to 0.66 in non-storm years. Probability of colony re-occupation declined as a function of storm date and increased with pre-storm nest success. Disturbance rate from avian predators did not increase post-storm compared to pre-storm periods. Nest survival increased with colony size and decreased in both late-season (non-storm) and post-storm time periods. Mean probability of chick survival was 0.20 ± 0.06 (mean ± SD) for peak nesting period in non-storm years, whereas mean predicted chick survival was 0.003–0.004 in storm years and in renesting periods in all years. Storm surge resulted in nearly complete loss of Least Tern breeding productivity despite renesting attempts and colony re-occupation after storms. I found no evidence that avian predation increased post-storm as a result of habitat changes; rather, similarly low productivity was observed for late-season breeding attempts in non-storm years. Repeated storm surge events could pose a serious threat to the viability of Mississippi’s coastal-nesting Least Tern population, and protection of Least Terns during early and peak nesting seasons is critical for ensuring breeding success.
{"title":"Poor reproductive performance of Least Terns after tropical cyclones in Mississippi USA suggests delayed nesting seriously reduces colony productivity","authors":"Abigail J Darrah","doi":"10.1093/ornithapp/duae003","DOIUrl":"https://doi.org/10.1093/ornithapp/duae003","url":null,"abstract":"Coastal birds that rely on sandy beaches for breeding are vulnerable to catastrophic flooding events resulting from tropical cyclones. The effects of storm surge on annual productivity depend on the propensity and success of renesting attempts post-storm. From 2017 to 2021, I investigated the effects of storm surge on Least Tern (Sternula antillarum) annual productivity, renesting probability, and nest and chick survival after storms on Mississippi’s Gulf of Mexico Coast. Tropical cyclones made landfall during peak breeding period in 3 of these years, resulting in complete overwash of all colonies. Observers monitored daily nest survival, productivity (maximum fledge count per maximum nest count), and frequency of disturbance from avian predators at each colony. Total annual productivity (fledge count per nest count across the study area) summed across colonies ranged from 0.00 to 0.07 in storm years and from 0.29 to 0.66 in non-storm years. Probability of colony re-occupation declined as a function of storm date and increased with pre-storm nest success. Disturbance rate from avian predators did not increase post-storm compared to pre-storm periods. Nest survival increased with colony size and decreased in both late-season (non-storm) and post-storm time periods. Mean probability of chick survival was 0.20 ± 0.06 (mean ± SD) for peak nesting period in non-storm years, whereas mean predicted chick survival was 0.003–0.004 in storm years and in renesting periods in all years. Storm surge resulted in nearly complete loss of Least Tern breeding productivity despite renesting attempts and colony re-occupation after storms. I found no evidence that avian predation increased post-storm as a result of habitat changes; rather, similarly low productivity was observed for late-season breeding attempts in non-storm years. Repeated storm surge events could pose a serious threat to the viability of Mississippi’s coastal-nesting Least Tern population, and protection of Least Terns during early and peak nesting seasons is critical for ensuring breeding success.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139578417","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}
Pub Date : 2023-12-19DOI: 10.1093/ornithapp/duad064
Rachel M Richardson, Courtney L Amundson, James A Johnson, Marc D Romano, Audrey R Taylor, Michael D Fleming, Steven M Matsuoka
The McKay’s Bunting (Plectrophenax hyperboreus) is endemic to Alaska, breeds solely on the remote and uninhabited St. Matthew and Hall islands (332 km2) in the central Bering Sea, and is designated as a species of high conservation concern due to its small population size and restricted range. A previous hypothesized population estimate (~2,800—6,000 individuals) was greatly increased (~31,200 individuals) after systematic surveys of the species’ entire breeding range in 2003, establishing McKay’s Bunting as one of the rarest passerines in North America. In 2018, we replicated the 2003 surveys and used density surface models to estimate breeding season densities, distributions, and population change over the intervening time period. Our results indicate that the McKay's Bunting population declined by 38% (95% CI: 27—48%) from ~31,560 to 19,481 individuals since 2003. Spatial model predictions showed no areas with an increase of birds on either St. Matthew or Hall islands but revealed declines across 13% (42 km2) of St. Matthew Island. Declines disproportionately occurred both in marginal habitats with reduced rocky nesting substrate and in high-density hotspots along the coast of St. Matthew Island. The total area occupied by breeding adults decreased by 8%, and high-density hotspots shifted inland from the coast of St. Matthew Island to higher elevations on both islands, the latter potentially responses to exceptionally warm weather and reduced spring snow cover in 2018. Additionally, we observed low numbers of predators and interspecific competitors in 2018 suggesting these did not cause the decline. Our findings indicate that McKay’s Bunting meets international standards for elevating its conservation status from Least Concern to Endangered based on the International Union for Conservation of Nature Red List of Threatened Species ranking criteria. Additional population monitoring and studies to identify the causal mechanisms of the recent population decline of this rare species could assist future population assessments.
{"title":"Rapid population decline in McKay's Bunting, an Alaskan endemic, highlights the species’ current status relative to international standards for vulnerable species","authors":"Rachel M Richardson, Courtney L Amundson, James A Johnson, Marc D Romano, Audrey R Taylor, Michael D Fleming, Steven M Matsuoka","doi":"10.1093/ornithapp/duad064","DOIUrl":"https://doi.org/10.1093/ornithapp/duad064","url":null,"abstract":"The McKay’s Bunting (Plectrophenax hyperboreus) is endemic to Alaska, breeds solely on the remote and uninhabited St. Matthew and Hall islands (332 km2) in the central Bering Sea, and is designated as a species of high conservation concern due to its small population size and restricted range. A previous hypothesized population estimate (~2,800—6,000 individuals) was greatly increased (~31,200 individuals) after systematic surveys of the species’ entire breeding range in 2003, establishing McKay’s Bunting as one of the rarest passerines in North America. In 2018, we replicated the 2003 surveys and used density surface models to estimate breeding season densities, distributions, and population change over the intervening time period. Our results indicate that the McKay's Bunting population declined by 38% (95% CI: 27—48%) from ~31,560 to 19,481 individuals since 2003. Spatial model predictions showed no areas with an increase of birds on either St. Matthew or Hall islands but revealed declines across 13% (42 km2) of St. Matthew Island. Declines disproportionately occurred both in marginal habitats with reduced rocky nesting substrate and in high-density hotspots along the coast of St. Matthew Island. The total area occupied by breeding adults decreased by 8%, and high-density hotspots shifted inland from the coast of St. Matthew Island to higher elevations on both islands, the latter potentially responses to exceptionally warm weather and reduced spring snow cover in 2018. Additionally, we observed low numbers of predators and interspecific competitors in 2018 suggesting these did not cause the decline. Our findings indicate that McKay’s Bunting meets international standards for elevating its conservation status from Least Concern to Endangered based on the International Union for Conservation of Nature Red List of Threatened Species ranking criteria. Additional population monitoring and studies to identify the causal mechanisms of the recent population decline of this rare species could assist future population assessments.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138820725","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}
Pub Date : 2023-12-07DOI: 10.1093/ornithapp/duad062
Douglas C Tozer, Annie M Bracey, Giuseppe E Fiorino, Thomas M Gehring, Erin E Gnass Giese, Greg P Grabas, Robert W Howe, Gregory J Lawrence, Gerald J Niemi, Bridget A Wheelock, Danielle M Ethier
Wetlands of the Laurentian Great Lakes of North America (i.e., lakes Superior, Michigan, Huron, Erie, and Ontario) provide critical habitat for marsh birds. We used 11 years (2011–2021) of data collected by the Great Lakes Coastal Wetland Monitoring Program at 1,962 point-count locations in 792 wetlands to quantify the first-ever annual abundance indices and trends of 18 marsh-breeding bird species in coastal wetlands throughout the entire Great Lakes. Nine species (50%) increased by 8–37% per year across all of the Great Lakes combined, whereas none decreased. Twelve species (67%) increased by 5–50% per year in at least 1 of the 5 Great Lakes, whereas only 3 species (17%) decreased by 2–10% per year in at least 1 of the lakes. There were more positive trends among lakes and species (n = 34, 48%) than negative trends (n = 5, 7%). These large increases are welcomed because most of the species are of conservation concern in the Great Lakes. Trends were likely caused by long-term, cyclical fluctuations in Great Lakes water levels. Lake levels increased over most of the study, which inundated vegetation and increased open water-vegetation interspersion and open water extent, all of which are known to positively influence abundance of most of the increasing species and negatively influence abundance of all of the decreasing species. Coastal wetlands may be more important for marsh birds than once thought if they provide high-lake-level-induced population pulses for species of conservation concern. Coastal wetland protection and restoration are of utmost importance to safeguard this process. Future climate projections show increases in lake levels over the coming decades, which will cause “coastal squeeze” of many wetlands if they are unable to migrate landward fast enough to keep pace. If this happens, less habitat will be available to support periodic pulses in marsh bird abundance, which appear to be important for regional population dynamics. Actions that allow landward migration of coastal wetlands during increasing lake levels by removing or preventing barriers to movement, such as shoreline hardening, will be useful for maintaining marsh bird breeding habitat in the Great Lakes.
{"title":"Increasing marsh bird abundance in coastal wetlands of the Great Lakes, 2011–2021, likely caused by increasing water levels","authors":"Douglas C Tozer, Annie M Bracey, Giuseppe E Fiorino, Thomas M Gehring, Erin E Gnass Giese, Greg P Grabas, Robert W Howe, Gregory J Lawrence, Gerald J Niemi, Bridget A Wheelock, Danielle M Ethier","doi":"10.1093/ornithapp/duad062","DOIUrl":"https://doi.org/10.1093/ornithapp/duad062","url":null,"abstract":"Wetlands of the Laurentian Great Lakes of North America (i.e., lakes Superior, Michigan, Huron, Erie, and Ontario) provide critical habitat for marsh birds. We used 11 years (2011–2021) of data collected by the Great Lakes Coastal Wetland Monitoring Program at 1,962 point-count locations in 792 wetlands to quantify the first-ever annual abundance indices and trends of 18 marsh-breeding bird species in coastal wetlands throughout the entire Great Lakes. Nine species (50%) increased by 8–37% per year across all of the Great Lakes combined, whereas none decreased. Twelve species (67%) increased by 5–50% per year in at least 1 of the 5 Great Lakes, whereas only 3 species (17%) decreased by 2–10% per year in at least 1 of the lakes. There were more positive trends among lakes and species (n = 34, 48%) than negative trends (n = 5, 7%). These large increases are welcomed because most of the species are of conservation concern in the Great Lakes. Trends were likely caused by long-term, cyclical fluctuations in Great Lakes water levels. Lake levels increased over most of the study, which inundated vegetation and increased open water-vegetation interspersion and open water extent, all of which are known to positively influence abundance of most of the increasing species and negatively influence abundance of all of the decreasing species. Coastal wetlands may be more important for marsh birds than once thought if they provide high-lake-level-induced population pulses for species of conservation concern. Coastal wetland protection and restoration are of utmost importance to safeguard this process. Future climate projections show increases in lake levels over the coming decades, which will cause “coastal squeeze” of many wetlands if they are unable to migrate landward fast enough to keep pace. If this happens, less habitat will be available to support periodic pulses in marsh bird abundance, which appear to be important for regional population dynamics. Actions that allow landward migration of coastal wetlands during increasing lake levels by removing or preventing barriers to movement, such as shoreline hardening, will be useful for maintaining marsh bird breeding habitat in the Great Lakes.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138562834","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}
Pub Date : 2023-11-29DOI: 10.1093/ornithapp/duad056
Adam C Smith, Allison D. Binley, Lindsay Daly, Brandon P M Edwards, Danielle Ethier, Barbara Frei, David Iles, Timothy D Meehan, Nicole L Michel, Paul A Smith
Population trend estimates form the core of avian conservation assessments in North America and indicate important changes in the state of the natural world. The models used to estimate these trends would be more efficient and informative for conservation if they explicitly considered the spatial locations of the monitoring data. We created spatially explicit versions of some standard status and trend models applied to long-term monitoring data for birds across North America. We compared the spatial models to simpler non-spatial versions of the same models, fitting them to simulated data and real data from 3 broad-scale monitoring programs: the North American Breeding Bird Survey (BBS), the Christmas Bird Count, and a collection of programs we refer to as Migrating Shorebird Surveys. All the models generally reproduced the simulated trends and population trajectories when there were many data, and the spatial models performed better when there were fewer data and in locations where the local trends differed from the range-wide means. When fit to real data, the spatial models revealed interesting spatial patterns in trend, such as recent population increases along the Appalachian Mountains for the Eastern Whip-poor-will (Antrostomus vociferus), that were much less apparent in results from the non-spatial versions. The spatial models also had higher out-of-sample predictive accuracy than the non-spatial models for a selection of species using BBS data. The spatially explicit sharing of information allows fitting the models with much smaller strata, allowing for finer-grained patterns in trends. Spatially informed trends will facilitate more locally relevant conservation, highlight areas of conservation successes and challenges, and help generate and test hypotheses about the spatially dependent drivers of population change.
{"title":"Spatially explicit Bayesian hierarchical models improve estimates of avian population status and trends","authors":"Adam C Smith, Allison D. Binley, Lindsay Daly, Brandon P M Edwards, Danielle Ethier, Barbara Frei, David Iles, Timothy D Meehan, Nicole L Michel, Paul A Smith","doi":"10.1093/ornithapp/duad056","DOIUrl":"https://doi.org/10.1093/ornithapp/duad056","url":null,"abstract":"Population trend estimates form the core of avian conservation assessments in North America and indicate important changes in the state of the natural world. The models used to estimate these trends would be more efficient and informative for conservation if they explicitly considered the spatial locations of the monitoring data. We created spatially explicit versions of some standard status and trend models applied to long-term monitoring data for birds across North America. We compared the spatial models to simpler non-spatial versions of the same models, fitting them to simulated data and real data from 3 broad-scale monitoring programs: the North American Breeding Bird Survey (BBS), the Christmas Bird Count, and a collection of programs we refer to as Migrating Shorebird Surveys. All the models generally reproduced the simulated trends and population trajectories when there were many data, and the spatial models performed better when there were fewer data and in locations where the local trends differed from the range-wide means. When fit to real data, the spatial models revealed interesting spatial patterns in trend, such as recent population increases along the Appalachian Mountains for the Eastern Whip-poor-will (Antrostomus vociferus), that were much less apparent in results from the non-spatial versions. The spatial models also had higher out-of-sample predictive accuracy than the non-spatial models for a selection of species using BBS data. The spatially explicit sharing of information allows fitting the models with much smaller strata, allowing for finer-grained patterns in trends. Spatially informed trends will facilitate more locally relevant conservation, highlight areas of conservation successes and challenges, and help generate and test hypotheses about the spatially dependent drivers of population change.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535455","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}
Pub Date : 2023-11-15DOI: 10.1093/ornithapp/duad061
Whitney A Watson, Daniel F Hofstadter, Gavin M Jones, H Anu Kramer, Nicholas F Kryshak, Ceeanna J Zulla, Sheila A Whitmore, Virginia O’Rourke, John J Keane, R J Gutiérrez, M Zachariah Peery
Characterizing natal dispersal can help manage the spread of invasive species expanding their ranges in response to land use and climate change. The Barred Owl (Strix varia) is a prominent example of an apex predator undergoing a rapid range expansion, having spread from eastern to western North America where it is now hyperabundant—threatening the Northern Spotted Owl (S. occidentalis caurina) with extinction and potentially endangering many other native species. We attached satellite tags to 31 Barred Owl juveniles at the southern leading edge of the Barred Owl’s expanding range in California to characterize natal dispersal patterns and inform management. Juveniles traveled up to 100 km from natal territories and experienced high mortality (annual survival = 0.204). At landscape scales, juveniles preferentially used forests, shrublands, and lower elevations during dispersal and avoided grasslands and burned areas. At finer scales, juveniles preferred shorter (younger) forests, lower elevations, and drainages, and avoided unforested areas. Our results suggest the Barred Owl range expansion is being driven primarily by high reproductive rates and densities despite low juvenile survival rates and dispersal through putatively suboptimal younger forests as a result of exclusion from high-quality habitat by territorial individuals. These findings also point to several strategies for conserving Spotted Owls and other native species in the Barred Owl’s expanded range, including: (1) creating and maintaining Barred Owl-free reserves bounded by open or high elevation areas; (2) creating reserves large enough to reduce immigration by long-distance dispersers; and (3) removing Barred Owls from large riparian corridors.
描述出生扩散的特征可以帮助管理入侵物种的传播，根据土地利用和气候变化扩大其范围。横斑猫头鹰(Strix varia)是一种正在经历快速扩张的顶级捕食者的突出例子，它从北美东部扩散到西部，现在在那里它的数量非常丰富，威胁着北方斑点猫头鹰(S. occidentalis caurina)的灭绝，并可能危及许多其他本地物种。我们将卫星标签贴在31只横斑猫头鹰的幼崽身上，这些幼崽位于加州横斑猫头鹰不断扩大的活动范围的南部边缘，以表征出生时的扩散模式，并为管理提供信息。幼鲸从出生地迁徙到100公里外，死亡率很高(年存活率= 0.204)。在景观尺度上，幼鱼在扩散过程中优先利用森林、灌丛和低海拔地区，避开草原和燃烧区。在较小的尺度上，幼鱼更喜欢较短的(年轻的)森林，低海拔和排水，并避开无森林的地区。我们的研究结果表明，横斑猫头鹰的范围扩张主要是由高繁殖率和密度驱动的，尽管幼崽存活率很低，并且由于被领地个体排除在高质量栖息地之外而在假定的次优年轻森林中扩散。这些发现还指出了在横斑猫头鹰扩大的范围内保护斑点猫头鹰和其他本地物种的几种策略，包括:(1)建立和维护以开放或高海拔地区为边界的无横斑猫头鹰保护区;(2)建立足够大的保护区，以减少远距离分散者的移民;(3)清除大型河岸走廊上的横斑猫头鹰。
{"title":"Characterizing juvenile dispersal dynamics of invasive Barred Owls: Implications for management","authors":"Whitney A Watson, Daniel F Hofstadter, Gavin M Jones, H Anu Kramer, Nicholas F Kryshak, Ceeanna J Zulla, Sheila A Whitmore, Virginia O’Rourke, John J Keane, R J Gutiérrez, M Zachariah Peery","doi":"10.1093/ornithapp/duad061","DOIUrl":"https://doi.org/10.1093/ornithapp/duad061","url":null,"abstract":"Characterizing natal dispersal can help manage the spread of invasive species expanding their ranges in response to land use and climate change. The Barred Owl (Strix varia) is a prominent example of an apex predator undergoing a rapid range expansion, having spread from eastern to western North America where it is now hyperabundant—threatening the Northern Spotted Owl (S. occidentalis caurina) with extinction and potentially endangering many other native species. We attached satellite tags to 31 Barred Owl juveniles at the southern leading edge of the Barred Owl’s expanding range in California to characterize natal dispersal patterns and inform management. Juveniles traveled up to 100 km from natal territories and experienced high mortality (annual survival = 0.204). At landscape scales, juveniles preferentially used forests, shrublands, and lower elevations during dispersal and avoided grasslands and burned areas. At finer scales, juveniles preferred shorter (younger) forests, lower elevations, and drainages, and avoided unforested areas. Our results suggest the Barred Owl range expansion is being driven primarily by high reproductive rates and densities despite low juvenile survival rates and dispersal through putatively suboptimal younger forests as a result of exclusion from high-quality habitat by territorial individuals. These findings also point to several strategies for conserving Spotted Owls and other native species in the Barred Owl’s expanded range, including: (1) creating and maintaining Barred Owl-free reserves bounded by open or high elevation areas; (2) creating reserves large enough to reduce immigration by long-distance dispersers; and (3) removing Barred Owls from large riparian corridors.","PeriodicalId":501493,"journal":{"name":"The Condor: Ornithological Applications","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535453","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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