ABSTRACT The San Clemente Bell′s Sparrow (Artemisiospiza belli clementeae) is a federally threatened subspecies endemic to San Clemente Island, California. Previous research suggested dependence on boxthorn (Lycium californicum) as breeding habitat and nesting substrate; however, this conclusion was based on data collected when introduced feral ungulates had severely degraded the soil and vegetation cover. Since removal of the ungulates, native vegetation has gradually increased and the San Clemente Bell′s Sparrows have expanded into areas where habitat had been unsuitable. To explore how Bell′s Sparrows use these areas, we examined reproductive metrics associated with habitat covariates gathered at 214 nest sites used by Bell′s Sparrows from 2014 to 2016. We found that nest success in boxthorn habitat, previously considered an essential habitat for Bell′s Sparrow nesting, was similar to success in alternative habitat types. Our findings contradict previous conclusions that Bell′s Sparrows were boxthorn-dependent. We believe this previously documented relationship was likely due to the lack of available alternative nesting habitat following years of feral ungulate degradation, and Bell′s Sparrows now reproduce in multiple habitat types and throughout most of San Clemente Island. Furthermore, our findings illustrate the importance of long-term monitoring and corresponding adaptive management when monitoring species in changing and recovering landscapes.
摘要圣克莱门特贝尔麻雀（Artemissopiza belli clementeae）是加利福尼亚州圣克莱门特岛的一个联邦濒危亚种。先前的研究表明，依赖于沙棘（Lycium californicum）作为繁殖栖息地和筑巢基质；然而，这一结论是基于引入野生有蹄类动物严重退化土壤和植被时收集的数据得出的。自从有蹄类动物被移除后，当地植被逐渐增加，圣克莱门特贝尔麻雀已经扩展到不适合栖息地的地区。为了探索贝尔麻雀如何使用这些区域，我们检查了2014年至2016年在贝尔麻雀使用的214个巢点收集的与栖息地协变量相关的繁殖指标。我们发现，在以前被认为是贝尔麻雀筑巢的重要栖息地的沙棘栖息地中，巢穴的成功与在其他栖息地类型中的成功相似。我们的发现与之前的结论相矛盾，即贝尔的麻雀是依赖于荆棘的。我们认为，这种先前记录的关系可能是由于多年的野生有蹄类动物退化后缺乏可用的替代筑巢栖息地，贝尔麻雀现在在多种栖息地类型和圣克莱门特岛的大部分地区繁殖。此外，我们的研究结果说明了在监测景观变化和恢复中的物种时，长期监测和相应的适应性管理的重要性。
{"title":"Reproductive success of the threatened San Clemente Bell's Sparrow (Artemisiospiza belli clementeae) in recovering habitats is similar to success in historical habitat","authors":"Susan T. Meiman, Emma E. Deleon, A. Bridges","doi":"10.1093/condor/duz071","DOIUrl":"https://doi.org/10.1093/condor/duz071","url":null,"abstract":"ABSTRACT The San Clemente Bell′s Sparrow (Artemisiospiza belli clementeae) is a federally threatened subspecies endemic to San Clemente Island, California. Previous research suggested dependence on boxthorn (Lycium californicum) as breeding habitat and nesting substrate; however, this conclusion was based on data collected when introduced feral ungulates had severely degraded the soil and vegetation cover. Since removal of the ungulates, native vegetation has gradually increased and the San Clemente Bell′s Sparrows have expanded into areas where habitat had been unsuitable. To explore how Bell′s Sparrows use these areas, we examined reproductive metrics associated with habitat covariates gathered at 214 nest sites used by Bell′s Sparrows from 2014 to 2016. We found that nest success in boxthorn habitat, previously considered an essential habitat for Bell′s Sparrow nesting, was similar to success in alternative habitat types. Our findings contradict previous conclusions that Bell′s Sparrows were boxthorn-dependent. We believe this previously documented relationship was likely due to the lack of available alternative nesting habitat following years of feral ungulate degradation, and Bell′s Sparrows now reproduce in multiple habitat types and throughout most of San Clemente Island. Furthermore, our findings illustrate the importance of long-term monitoring and corresponding adaptive management when monitoring species in changing and recovering landscapes.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 11"},"PeriodicalIF":2.4,"publicationDate":"2020-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz071","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45541081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rose J. Swift, Michael J. Anteau, Megan M. Ring, Dustin L. Toy, M. Sherfy
ABSTRACT Upon reproductive failure, many bird species make a secondary attempt at nesting (hereafter, ″renesting”). Renesting may be an effective strategy to maximize current and lifetime reproductive success, but individuals face uncertainty in the probability of success because reproductive attempts initiated later in the breeding season often have reduced nest, pre-fledging, and post-fledging brood survival. We evaluated renesting propensity, renesting intervals, and renest reproductive success of Piping Plovers (Charadrius melodus) by following 1,922 nests and 1,785 unique breeding adults from 2014 to 2016 in the Northern Great Plains of the United States. The apparent renesting rate for individuals was 25% for reproductive attempts that failed in the nest stage (egg laying and incubation) and only 1.2% for reproductive attempts when broods were lost. Renesting propensity declined if reproductive attempts failed during the brood-rearing stage, nests were depredated, reproductive failure occurred later in the breeding season, or individuals had previously renested that year. Additionally, plovers that nested on reservoirs were less likely to renest compared to other habitats. Renesting intervals declined when individuals had not already renested, were after-second-year adults without known prior breeding experience, and moved short distances between nest attempts. Renesting intervals also decreased if the attempt failed later in the season. Overall, reproductive success and daily nest survival were lower for renests than first nests throughout the breeding season. Furthermore, renests on reservoirs had reduced apparent reproductive success and daily nest survival unless the predicted amount of habitat on reservoirs increased within the breeding season. Our results provide important demographic measures for this threatened species and suggest that predation- and water-management strategies that maximize success of early nests would be more likely to increase productivity. Altogether, renesting appears to be an unproductive reproductive strategy to replace lost reproductive attempts for Piping Plovers breeding in the Northern Great Plains.
{"title":"Low renesting propensity and reproductive success make renesting unproductive for the threatened Piping Plover (Charadrius melodus)","authors":"Rose J. Swift, Michael J. Anteau, Megan M. Ring, Dustin L. Toy, M. Sherfy","doi":"10.1093/condor/duz066","DOIUrl":"https://doi.org/10.1093/condor/duz066","url":null,"abstract":"ABSTRACT Upon reproductive failure, many bird species make a secondary attempt at nesting (hereafter, ″renesting”). Renesting may be an effective strategy to maximize current and lifetime reproductive success, but individuals face uncertainty in the probability of success because reproductive attempts initiated later in the breeding season often have reduced nest, pre-fledging, and post-fledging brood survival. We evaluated renesting propensity, renesting intervals, and renest reproductive success of Piping Plovers (Charadrius melodus) by following 1,922 nests and 1,785 unique breeding adults from 2014 to 2016 in the Northern Great Plains of the United States. The apparent renesting rate for individuals was 25% for reproductive attempts that failed in the nest stage (egg laying and incubation) and only 1.2% for reproductive attempts when broods were lost. Renesting propensity declined if reproductive attempts failed during the brood-rearing stage, nests were depredated, reproductive failure occurred later in the breeding season, or individuals had previously renested that year. Additionally, plovers that nested on reservoirs were less likely to renest compared to other habitats. Renesting intervals declined when individuals had not already renested, were after-second-year adults without known prior breeding experience, and moved short distances between nest attempts. Renesting intervals also decreased if the attempt failed later in the season. Overall, reproductive success and daily nest survival were lower for renests than first nests throughout the breeding season. Furthermore, renests on reservoirs had reduced apparent reproductive success and daily nest survival unless the predicted amount of habitat on reservoirs increased within the breeding season. Our results provide important demographic measures for this threatened species and suggest that predation- and water-management strategies that maximize success of early nests would be more likely to increase productivity. Altogether, renesting appears to be an unproductive reproductive strategy to replace lost reproductive attempts for Piping Plovers breeding in the Northern Great Plains.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 18"},"PeriodicalIF":2.4,"publicationDate":"2020-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz066","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43851923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Colyn, C. L. Henderson, R. Altwegg, H. Smit-Robinson
ABSTRACT Habitat transformation and loss is one of the greatest threats currently facing avian species. The cumulative impact of climate change on habitat loss is projected to produce disproportionate risk for endemic high-altitude species. The Southern Bald Ibis (Geronticus calvus) is an endemic high-altitude species found throughout highland grassland habitats in South Africa and Lesotho. The historical distribution has contracted notably and causal factors remain ambiguous. Furthermore, the historical population (1950–1970) was believed to be stable, but recent local surveys suggest colony declines and the current global population status remains largely unquantified. We assessed the current distribution and population status of the species through predictive modeling and trends in historical and recent colony counts across the species' range. We examined climate and habitat change as potential causal factors contributing to the historical contraction in distribution, and projected the potential impact of future climate change predicted by global circulation models. Our study confirms that Southern Bald Ibis are of conservation concern. The loss of grasslands to expanding woody vegetation through bush encroachment was the most detrimental habitat transformation type associated with decreased colony growth and colony collapse. We recommend maintaining a minimum threshold of 50% or greater intact grassland habitat surrounding colonies to reduce colony extinction risk and promote colony persistence.
{"title":"Habitat transformation and climate change: Implications for the distribution, population status, and colony extinction of Southern Bald Ibis (Geronticus calvus) in southern Africa","authors":"R. Colyn, C. L. Henderson, R. Altwegg, H. Smit-Robinson","doi":"10.1093/condor/duz064","DOIUrl":"https://doi.org/10.1093/condor/duz064","url":null,"abstract":"ABSTRACT Habitat transformation and loss is one of the greatest threats currently facing avian species. The cumulative impact of climate change on habitat loss is projected to produce disproportionate risk for endemic high-altitude species. The Southern Bald Ibis (Geronticus calvus) is an endemic high-altitude species found throughout highland grassland habitats in South Africa and Lesotho. The historical distribution has contracted notably and causal factors remain ambiguous. Furthermore, the historical population (1950–1970) was believed to be stable, but recent local surveys suggest colony declines and the current global population status remains largely unquantified. We assessed the current distribution and population status of the species through predictive modeling and trends in historical and recent colony counts across the species' range. We examined climate and habitat change as potential causal factors contributing to the historical contraction in distribution, and projected the potential impact of future climate change predicted by global circulation models. Our study confirms that Southern Bald Ibis are of conservation concern. The loss of grasslands to expanding woody vegetation through bush encroachment was the most detrimental habitat transformation type associated with decreased colony growth and colony collapse. We recommend maintaining a minimum threshold of 50% or greater intact grassland habitat surrounding colonies to reduce colony extinction risk and promote colony persistence.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 17"},"PeriodicalIF":2.4,"publicationDate":"2020-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz064","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44173473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Connor M. Wood, R. J. Gutiérrez, J. Keane, M. Z. Peery
ABSTRACT Biological invasions are most practical to manage when invasive species population densities are low. Despite a potentially narrow window of opportunity for efficient management, managers tend to delay intervention because the cost of prompt action is often high and resources are limited. The Barred Owl (Strix varia) invaded and colonized the entire range of the Northern Spotted Owl (S. occidentalis caurina), but insufficient population data contributed to delays in action until the Barred Owl posed an existential threat to the Spotted Owl. The leading edge of the Barred Owl expansion has since reached the Sierra Nevada, the core range of the California Spotted Owl (S. o. occidentalis). We conducted passive acoustic surveys within 400-ha grid cells across ∼6,200 km2 in the northern Sierra Nevada and detected a 2.6-fold increase in Barred Owl site occupancy between 2017 and 2018, from 0.082 (85% confidence interval: 0.045–0.12) to 0.21 (0.14–0.28). The probability of Barred Owl site colonization increased with the amount of older forest, suggesting that Barred Owls are first occupying the preferred habitat of Spotted Owls. GPS-tagged Barred Owls (n = 10) generally displayed seasonal and interannual site fidelity over territories averaging 411 ha (range: 150–513 ha), suggesting that our occupancy estimates were not substantially upwardly biased by “double counting” individuals whose territories spanned multiple grid cells. Given the Barred Owl's demonstrated threat to the Northern Spotted Owl, we believe our findings advise the Precautionary Principle, which posits that management actions such as invasive species removal should be taken despite uncertainties about, for example, true rates of population growth if the cost of inaction is high. In this case, initiating Barred Owl removals in the Sierra Nevada before the population grows further will likely make such action more cost-effective and more humane than if it is delayed. It could also prevent the extirpation of the California Spotted Owl from its core range.
当入侵物种种群密度较低时，生物入侵是最实用的管理方法。尽管有效管理的机会之窗可能很窄，但管理人员往往推迟干预，因为迅速行动的成本往往很高，资源又有限。横斑猫头鹰(Strix varia)入侵并殖民了北斑猫头鹰(S. occidentalis caurina)的整个范围，但种群数据不足导致行动延迟，直到横斑猫头鹰对斑点猫头鹰构成生存威胁。横斑猫头鹰扩张的前沿已经到达了内华达山脉，这是加利福尼亚斑点猫头鹰(s.o. occidentalis)的核心范围。我们在内华达山脉北部6200平方公里的400公顷网格单元内进行了被动声学调查，发现在2017年至2018年期间，横斑猫头鹰的场地占用率增加了2.6倍，从0.082(85%置信区间:0.045-0.12)增加到0.21(0.14-0.28)。横斑猫头鹰定居地点的可能性随着老森林数量的增加而增加，这表明横斑猫头鹰首先占据了斑点猫头鹰的首选栖息地。gps标记的横斑猫头鹰(n = 10)通常在平均411公顷(范围:150-513公顷)的领土上表现出季节性和年际的保真度，这表明我们的占用估计并没有因为“重复计算”跨越多个网格单元的个体而大幅上升。考虑到斑鸮对北方斑点猫头鹰的威胁，我们认为我们的研究结果建议采取预防原则，该原则认为，尽管存在不确定性，例如，如果不采取行动的成本很高，则应该采取诸如入侵物种清除之类的管理行动。在这种情况下，在内华达山脉的横斑猫头鹰数量进一步增长之前开始清除它们，可能会比推迟行动更具成本效益，也更人道。它还可以防止加州斑点猫头鹰从其核心范围内灭绝。
{"title":"Early detection of rapid Barred Owl population growth within the range of the California Spotted Owl advises the Precautionary Principle","authors":"Connor M. Wood, R. J. Gutiérrez, J. Keane, M. Z. Peery","doi":"10.1093/condor/duz058","DOIUrl":"https://doi.org/10.1093/condor/duz058","url":null,"abstract":"ABSTRACT Biological invasions are most practical to manage when invasive species population densities are low. Despite a potentially narrow window of opportunity for efficient management, managers tend to delay intervention because the cost of prompt action is often high and resources are limited. The Barred Owl (Strix varia) invaded and colonized the entire range of the Northern Spotted Owl (S. occidentalis caurina), but insufficient population data contributed to delays in action until the Barred Owl posed an existential threat to the Spotted Owl. The leading edge of the Barred Owl expansion has since reached the Sierra Nevada, the core range of the California Spotted Owl (S. o. occidentalis). We conducted passive acoustic surveys within 400-ha grid cells across ∼6,200 km2 in the northern Sierra Nevada and detected a 2.6-fold increase in Barred Owl site occupancy between 2017 and 2018, from 0.082 (85% confidence interval: 0.045–0.12) to 0.21 (0.14–0.28). The probability of Barred Owl site colonization increased with the amount of older forest, suggesting that Barred Owls are first occupying the preferred habitat of Spotted Owls. GPS-tagged Barred Owls (n = 10) generally displayed seasonal and interannual site fidelity over territories averaging 411 ha (range: 150–513 ha), suggesting that our occupancy estimates were not substantially upwardly biased by “double counting” individuals whose territories spanned multiple grid cells. Given the Barred Owl's demonstrated threat to the Northern Spotted Owl, we believe our findings advise the Precautionary Principle, which posits that management actions such as invasive species removal should be taken despite uncertainties about, for example, true rates of population growth if the cost of inaction is high. In this case, initiating Barred Owl removals in the Sierra Nevada before the population grows further will likely make such action more cost-effective and more humane than if it is delayed. It could also prevent the extirpation of the California Spotted Owl from its core range.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 10"},"PeriodicalIF":2.4,"publicationDate":"2020-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz058","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45403597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Maintaining a functionally connected network of high-quality habitat is one of the most effective responses to biodiversity loss. However, the spatial distribution of suitable habitat may shift over time in response to climate change. Taxa such as migratory forest landbirds are already undergoing climate-driven range shifts. Therefore, patches of climate-resilient habitat (also known as “climate refugia”) are especially valuable from a conservation perspective. Here, we performed maximum entropy (Maxent) species distribution modeling to predict suitable and potentially climate-resilient habitat in Nova Scotia, Canada, for 3 migratory forest landbirds: Rusty Blackbird (Euphagus carolinus), Olive-sided Flycatcher (Contopus cooperi), and Canada Warbler (Cardellina canadensis). We used a reverse stepwise elimination technique to identify covariates that influence habitat suitability for the target species at broad scales, including abiotic (topographic control of moisture and nutrient accumulation) and biotic (forest characteristics) covariates. As topography should be relatively unaffected by a changing climate and helps regulate the structure and composition of forest habitat, we posit that the inclusion of appropriate topographic features may support the identification of climate-resilient habitat. Of all covariates, depth to water table was the most important predictor of relative habitat suitability for the Rusty Blackbird and Canada Warbler, with both species showing a strong association with wet areas. Mean canopy height was the most important predictor for the Olive-sided Flycatcher, whereby the species was associated with taller trees. Our models, which comprise the finest-scale species distribution models available for these species in this region, further indicated that, for all species, habitat (1) remains relatively abundant and well distributed in Nova Scotia and (2) is often located in wet lowlands (a climate-resilient topographic landform). These findings suggest that opportunities remain to conserve breeding habitat for these species despite changing temperature and precipitation regimes.
{"title":"The benefits of using topographic features to predict climate-resilient habitat for migratory forest landbirds: An example for the Rusty Blackbird, Olive-sided Flycatcher, and Canada Warbler","authors":"S. Bale, K. Beazley, A. Westwood, Peter G. Bush","doi":"10.1093/condor/duz057","DOIUrl":"https://doi.org/10.1093/condor/duz057","url":null,"abstract":"ABSTRACT Maintaining a functionally connected network of high-quality habitat is one of the most effective responses to biodiversity loss. However, the spatial distribution of suitable habitat may shift over time in response to climate change. Taxa such as migratory forest landbirds are already undergoing climate-driven range shifts. Therefore, patches of climate-resilient habitat (also known as “climate refugia”) are especially valuable from a conservation perspective. Here, we performed maximum entropy (Maxent) species distribution modeling to predict suitable and potentially climate-resilient habitat in Nova Scotia, Canada, for 3 migratory forest landbirds: Rusty Blackbird (Euphagus carolinus), Olive-sided Flycatcher (Contopus cooperi), and Canada Warbler (Cardellina canadensis). We used a reverse stepwise elimination technique to identify covariates that influence habitat suitability for the target species at broad scales, including abiotic (topographic control of moisture and nutrient accumulation) and biotic (forest characteristics) covariates. As topography should be relatively unaffected by a changing climate and helps regulate the structure and composition of forest habitat, we posit that the inclusion of appropriate topographic features may support the identification of climate-resilient habitat. Of all covariates, depth to water table was the most important predictor of relative habitat suitability for the Rusty Blackbird and Canada Warbler, with both species showing a strong association with wet areas. Mean canopy height was the most important predictor for the Olive-sided Flycatcher, whereby the species was associated with taller trees. Our models, which comprise the finest-scale species distribution models available for these species in this region, further indicated that, for all species, habitat (1) remains relatively abundant and well distributed in Nova Scotia and (2) is often located in wet lowlands (a climate-resilient topographic landform). These findings suggest that opportunities remain to conserve breeding habitat for these species despite changing temperature and precipitation regimes.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 19"},"PeriodicalIF":2.4,"publicationDate":"2020-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60894092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aaron T. Pearse, K. Metzger, D. A. Brandt, Mark T. Bidwell, M. Harner, David M. Baasch, W. Harrell
ABSTRACT Migratory birds use numerous strategies to successfully complete twice-annual movements between breeding and wintering sites. Context for conservation and management can be provided by characterizing these strategies. Variations in strategy among and within individuals support population persistence in response to changes in land use and climate. We used location data from 58 marked Whooping Cranes (Grus americana) from 2010 to 2016 to characterize migration strategies in the U.S. Great Plains and Canadian Prairies and southern boreal region, and to explore sources of heterogeneity in their migration strategy, including space use, timing, and performance. Whooping Cranes completed ∼3,900-km migrations that averaged 29 days during spring and 45 days during autumn, while making 11–12 nighttime stops. At the scale of our analysis, individual Whooping Cranes showed little consistency in stopover sites used among migration seasons (i.e. low site fidelity). In contrast, individuals expressed a measure of consistency in timing, especially migration initiation dates. Whooping Cranes migrated at different times based on age and reproductive status, where adults with young initiated autumn migration after other birds, and adults with and without young initiated spring migration before subadult birds. Time spent at stopover sites was positively associated with migration bout length and negatively associated with time spent at previous stopover sites, indicating Whooping Cranes acquired energy resources at some stopover sites that they used to fuel migration. Whooping Cranes were faithful to a defined migration corridor but showed less fidelity in their selection of nighttime stopover sites; hence, spatial targeting of conservation actions may be better informed by associations with landscape and habitat features rather than documented past use at specific locations. The preservation of variation in migration strategies existing within this species that experienced a severe population bottleneck suggests that Whooping Cranes have maintained a capacity to adjust strategies when confronted with future changes in land use and climate.
{"title":"Heterogeneity in migration strategies of Whooping Cranes","authors":"Aaron T. Pearse, K. Metzger, D. A. Brandt, Mark T. Bidwell, M. Harner, David M. Baasch, W. Harrell","doi":"10.1093/condor/duz056","DOIUrl":"https://doi.org/10.1093/condor/duz056","url":null,"abstract":"ABSTRACT Migratory birds use numerous strategies to successfully complete twice-annual movements between breeding and wintering sites. Context for conservation and management can be provided by characterizing these strategies. Variations in strategy among and within individuals support population persistence in response to changes in land use and climate. We used location data from 58 marked Whooping Cranes (Grus americana) from 2010 to 2016 to characterize migration strategies in the U.S. Great Plains and Canadian Prairies and southern boreal region, and to explore sources of heterogeneity in their migration strategy, including space use, timing, and performance. Whooping Cranes completed ∼3,900-km migrations that averaged 29 days during spring and 45 days during autumn, while making 11–12 nighttime stops. At the scale of our analysis, individual Whooping Cranes showed little consistency in stopover sites used among migration seasons (i.e. low site fidelity). In contrast, individuals expressed a measure of consistency in timing, especially migration initiation dates. Whooping Cranes migrated at different times based on age and reproductive status, where adults with young initiated autumn migration after other birds, and adults with and without young initiated spring migration before subadult birds. Time spent at stopover sites was positively associated with migration bout length and negatively associated with time spent at previous stopover sites, indicating Whooping Cranes acquired energy resources at some stopover sites that they used to fuel migration. Whooping Cranes were faithful to a defined migration corridor but showed less fidelity in their selection of nighttime stopover sites; hence, spatial targeting of conservation actions may be better informed by associations with landscape and habitat features rather than documented past use at specific locations. The preservation of variation in migration strategies existing within this species that experienced a severe population bottleneck suggests that Whooping Cranes have maintained a capacity to adjust strategies when confronted with future changes in land use and climate.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 15"},"PeriodicalIF":2.4,"publicationDate":"2020-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz056","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48420319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Woodpeckers are often focal species for informing management of recently burned forests. Snags generated by wildfire provide key nesting and foraging resources for woodpeckers, and nest cavities excavated by woodpeckers are subsequently used by many other species. Habitat suitability models applicable in newly burned forest are important management tools for identifying areas likely to be used by nesting woodpeckers. Here we present and test predictive models for mapping woodpecker nest-site habitat across wildfire locations that can be used to inform post-fire planning and salvage logging decisions. From 2009 to 2016, we monitored 313 nest sites of 4 species—Black-backed Woodpecker (Picoides arcticus), Hairy Woodpecker (Dryobates villosus), White-headed Woodpecker (D. albolarvatus), and Northern Flicker (Colaptes auratus)—from 3 wildfires in the Northern Sierra Nevada and Southern Cascades 1–5 yr after fire. Using these data, we developed habitat suitability index models that compared nest vs. non-nest sites for each species using (1) exclusively remotely sensed covariates, and (2) combinations of remotely sensed and field-collected covariates. We emphasized predictive performance across wildfire locations when selecting models to retain generalizable habitat relationships useful for informing management in newly burned locations. We identified models for all 4 species with strong predictive performance across wildfire locations despite notable variation in conditions among locations, suggesting broad applicability to guide post-fire management in the Sierra Nevada region. Top models for nest-site selection underscored the importance of high burn severity at the local scale, lower burn severity at the 1-km scale, mid-sized nest-tree diameters, and nest trees with broken tops. Models restricted to remotely sensed covariates exhibited similar predictive performance as combination models and are valuable for mapping habitat across entire wildfire locations to help delineate project areas or habitat reserves. Combination models are especially relevant for design of silvicultural prescriptions.
{"title":"Predictive habitat suitability models for nesting woodpeckers following wildfire in the Sierra Nevada and Southern Cascades of California","authors":"B. Campos, Quresh S. Latif, R. Burnett, V. Saab","doi":"10.1093/condor/duz062","DOIUrl":"https://doi.org/10.1093/condor/duz062","url":null,"abstract":"ABSTRACT Woodpeckers are often focal species for informing management of recently burned forests. Snags generated by wildfire provide key nesting and foraging resources for woodpeckers, and nest cavities excavated by woodpeckers are subsequently used by many other species. Habitat suitability models applicable in newly burned forest are important management tools for identifying areas likely to be used by nesting woodpeckers. Here we present and test predictive models for mapping woodpecker nest-site habitat across wildfire locations that can be used to inform post-fire planning and salvage logging decisions. From 2009 to 2016, we monitored 313 nest sites of 4 species—Black-backed Woodpecker (Picoides arcticus), Hairy Woodpecker (Dryobates villosus), White-headed Woodpecker (D. albolarvatus), and Northern Flicker (Colaptes auratus)—from 3 wildfires in the Northern Sierra Nevada and Southern Cascades 1–5 yr after fire. Using these data, we developed habitat suitability index models that compared nest vs. non-nest sites for each species using (1) exclusively remotely sensed covariates, and (2) combinations of remotely sensed and field-collected covariates. We emphasized predictive performance across wildfire locations when selecting models to retain generalizable habitat relationships useful for informing management in newly burned locations. We identified models for all 4 species with strong predictive performance across wildfire locations despite notable variation in conditions among locations, suggesting broad applicability to guide post-fire management in the Sierra Nevada region. Top models for nest-site selection underscored the importance of high burn severity at the local scale, lower burn severity at the 1-km scale, mid-sized nest-tree diameters, and nest trees with broken tops. Models restricted to remotely sensed covariates exhibited similar predictive performance as combination models and are valuable for mapping habitat across entire wildfire locations to help delineate project areas or habitat reserves. Combination models are especially relevant for design of silvicultural prescriptions.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 27"},"PeriodicalIF":2.4,"publicationDate":"2020-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz062","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44294595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jessie Reese, C. Viverette, C. Tonra, Nicholas J. Bayly, T. Boves, Erik I. Johnson, Matthew S. Johnson, P. Marra, Elizabeth M. Ames, Ángela Caguazango, M. DeSaix, Alix E. Matthews, A. Molina, Katie L. Percy, Morgan C. Slevin, L. Bulluck
Estimates of migratory connectivity are needed for full annual cycle population models of migratory bird species experiencing rapid declines in abundance. One technique to determine migratory connectivity is through stable isotope analysis. This low-resolution method may be influenced by how data are calibrated between isotopes measured in precipitation and those measured in feathers, and can be informed by incorporating relative abundance into the assignment model. eBird abundance maps are a new tool combining citizen science data into a predictive species distribution model. In the Prothonotary Warbler (Protonotaria citrea), a wetland-associated songbird with a patchy breeding distribution, we sought to use stable-hydrogen isotope analysis informed by a species-specific calibration equation and eBird abundance data to determine the strength of migratory connectivity. We developed a species-specific calibration equation using known-origin samples from the breeding grounds and found that stable-hydrogen isotope values measured in precipitation explained 50% of the variation in stable-hydrogen isotope values among feathers. We found that the assignment model incorporating eBird abundance data correctly identified the true origins of 66% of individuals, and that the average assignment area (as a measure of precision) was 64% of the breeding distribution. These results represented a 7% increase in precision and a 3% decrease in accuracy when compared to a model that was not informed by abundance. Based on these models, wintering populations from 6 countries represented a mix of likely breeding origins, suggesting low migratory connectivity for Prothonotary Warblers. We found evidence that wintering latitude was related to likely breeding origin, with individuals at western wintering locations more likely to have southern breeding origins, but this relationship was weak. These results corroborate studies using archival light-level geolocators and high-resolution genetic markers, which also demonstrated weak migratory connectivity in this species. For patchily distributed species, eBird abundance data may not provide a useful increase in precision and accuracy for isotope assignments.
{"title":"Using stable isotopes to estimate migratory connectivity for a patchily distributed, wetland-associated Neotropical migrant","authors":"Jessie Reese, C. Viverette, C. Tonra, Nicholas J. Bayly, T. Boves, Erik I. Johnson, Matthew S. Johnson, P. Marra, Elizabeth M. Ames, Ángela Caguazango, M. DeSaix, Alix E. Matthews, A. Molina, Katie L. Percy, Morgan C. Slevin, L. Bulluck","doi":"10.1093/condor/duz052","DOIUrl":"https://doi.org/10.1093/condor/duz052","url":null,"abstract":"\u0000 Estimates of migratory connectivity are needed for full annual cycle population models of migratory bird species experiencing rapid declines in abundance. One technique to determine migratory connectivity is through stable isotope analysis. This low-resolution method may be influenced by how data are calibrated between isotopes measured in precipitation and those measured in feathers, and can be informed by incorporating relative abundance into the assignment model. eBird abundance maps are a new tool combining citizen science data into a predictive species distribution model. In the Prothonotary Warbler (Protonotaria citrea), a wetland-associated songbird with a patchy breeding distribution, we sought to use stable-hydrogen isotope analysis informed by a species-specific calibration equation and eBird abundance data to determine the strength of migratory connectivity. We developed a species-specific calibration equation using known-origin samples from the breeding grounds and found that stable-hydrogen isotope values measured in precipitation explained 50% of the variation in stable-hydrogen isotope values among feathers. We found that the assignment model incorporating eBird abundance data correctly identified the true origins of 66% of individuals, and that the average assignment area (as a measure of precision) was 64% of the breeding distribution. These results represented a 7% increase in precision and a 3% decrease in accuracy when compared to a model that was not informed by abundance. Based on these models, wintering populations from 6 countries represented a mix of likely breeding origins, suggesting low migratory connectivity for Prothonotary Warblers. We found evidence that wintering latitude was related to likely breeding origin, with individuals at western wintering locations more likely to have southern breeding origins, but this relationship was weak. These results corroborate studies using archival light-level geolocators and high-resolution genetic markers, which also demonstrated weak migratory connectivity in this species. For patchily distributed species, eBird abundance data may not provide a useful increase in precision and accuracy for isotope assignments.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2019-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz052","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48089377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Urbanization increasingly exposes birds to multiple sources of direct anthropogenic mortality. Collisions with buildings, and windows in particular, are a top bird mortality source, annually causing 365–988 million fatalities in the United States. Correlates of window collision rates have been studied at the scale of entire buildings and in relation to the surrounding landscape, and most studies have only assessed correlates for all birds combined without considering season- and species-specific risk factors. In Stillwater, Oklahoma, USA, we conducted bird collision surveys at 16 buildings to assess building structural-, vegetation-, and land cover-related collision correlates. Unlike past studies, we focused at the scale of individual building façades, and in addition to considering correlates for total collisions, we assessed correlates for different seasons and separately for 8 collision-prone species. Several façade-related features, including proportional glass coverage, façade length, and façade height, were positively associated with total collisions and collisions for most separate seasons and species. Total collisions were also greater at alcove-shaped façades than flat, curved, and portico-shaped façades. We found that collision correlates varied among seasons (e.g., surrounding lawn cover important in summer and fall, but not spring) and among species (e.g., surrounding impervious cover positively and negatively related to collisions of Painted Bunting [Passerina ciris] and American Robin [Turdus migratorius], respectively). Given the importance of glass proportion, collision reduction efforts should continue to focus on minimizing and/or treating glass surfaces on new and existing buildings. Our species- and season-specific assessments indicate that management of some collision risk factors may not be equally effective for all seasons and species. Future research, policy, and management that integrates information about collision risk for all bird species and seasons, and at multiple scales from building façades to the surrounding landscape, will be most effective at reducing total mortality from bird–window collisions.
{"title":"Building façade-level correlates of bird–window collisions in a small urban area","authors":"Corey S. Riding, T. O’Connell, S. Loss","doi":"10.1093/condor/duz065","DOIUrl":"https://doi.org/10.1093/condor/duz065","url":null,"abstract":"ABSTRACT Urbanization increasingly exposes birds to multiple sources of direct anthropogenic mortality. Collisions with buildings, and windows in particular, are a top bird mortality source, annually causing 365–988 million fatalities in the United States. Correlates of window collision rates have been studied at the scale of entire buildings and in relation to the surrounding landscape, and most studies have only assessed correlates for all birds combined without considering season- and species-specific risk factors. In Stillwater, Oklahoma, USA, we conducted bird collision surveys at 16 buildings to assess building structural-, vegetation-, and land cover-related collision correlates. Unlike past studies, we focused at the scale of individual building façades, and in addition to considering correlates for total collisions, we assessed correlates for different seasons and separately for 8 collision-prone species. Several façade-related features, including proportional glass coverage, façade length, and façade height, were positively associated with total collisions and collisions for most separate seasons and species. Total collisions were also greater at alcove-shaped façades than flat, curved, and portico-shaped façades. We found that collision correlates varied among seasons (e.g., surrounding lawn cover important in summer and fall, but not spring) and among species (e.g., surrounding impervious cover positively and negatively related to collisions of Painted Bunting [Passerina ciris] and American Robin [Turdus migratorius], respectively). Given the importance of glass proportion, collision reduction efforts should continue to focus on minimizing and/or treating glass surfaces on new and existing buildings. Our species- and season-specific assessments indicate that management of some collision risk factors may not be equally effective for all seasons and species. Future research, policy, and management that integrates information about collision risk for all bird species and seasons, and at multiple scales from building façades to the surrounding landscape, will be most effective at reducing total mortality from bird–window collisions.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 14"},"PeriodicalIF":2.4,"publicationDate":"2019-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44433596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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