Condor最新文献

{"title":"Radio-tracking reveals insight into survival and dynamic habitat selection of fledgling Cerulean Warblers","authors":"Douglas W. Raybuck, Jeffery L. Larkin, S. Stoleson, T. Boves","doi":"10.1093/condor/duz063","DOIUrl":"https://doi.org/10.1093/condor/duz063","url":null,"abstract":"ABSTRACT For most bird species, little is known about their ecology and survival between fledging and independence despite the potential for post-fledging survival to be a factor limiting population dynamics. Cerulean Warblers (Setophaga cerulea) are a declining migratory species, and full-life-cycle conservation efforts that include the post-fledging period are warranted to attempt to reverse their decline. To understand movement, habitat selection, and survival, we radio-tracked 20 fledglings throughout the dependent post-fledging period. Broods were split by their parents, typically (88%) left parental breeding territories within 12 days, and survivors moved 2.4 ± 0.7 km (mean ± SE) from their nest within the 28.1 ± 1.8 day tracking period. Fledglings were usually observed in the mid-canopy to upper canopy and selected habitat with greater mid-story cover, less basal area, and areas closer to water bodies, compared to available points, when considering data from the entire post-fledgling period. However, habitat selection varied with fledgling age. Young fledglings (0–2 days post-fledging) selected areas with greater sapling cover and less stand basal area, but as fledglings matured, they selected areas farther from canopy gaps with greater mid-story cover. Compared with nesting habitat selected by parents, fledglings used areas with smaller and more numerous trees, fewer canopy gaps, and greater mid-story cover. Survival of the entire period was 48 ± 14% and most (8/10) mortalities occurred within the first 3 days post-fledging. Evidence indicated eastern chipmunks (Tamias striatus) as the most common predator. Providing or retaining large tracts of forest is recommended to prevent the restriction of post-fledging dispersal, and managing forests to maintain a heterogeneous landscape that includes stands with numerous canopy gaps and dense understory (e.g., shelterwood harvests or late seral stage conditions) as well as stands with a dense mid-story (e.g., younger stands and riparian areas) appears to be important for this life stage.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 15"},"PeriodicalIF":2.4,"publicationDate":"2020-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz063","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46131163","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}

{"title":"Low first-year apparent survival of passerines in abandoned fields in northwestern Russia","authors":"D. Shitikov, Viktoria Grudinskaya, T. Makarova, T. Vaytina, S. Fedotova, S. Samsonov, A. Grabovsky","doi":"10.1093/condor/duaa008","DOIUrl":"https://doi.org/10.1093/condor/duaa008","url":null,"abstract":"ABSTRACT First-year survival probability of migratory passerines during the period between fledging and first reproduction is a highly variable parameter that has a major effect on population dynamics. We used a long-term mark–recapture dataset (2002–2018) to examine first-year survival of 3 passerine species breeding in abandoned agricultural fields of northwestern Russia: Booted Warbler (Iduna caligata), Whinchat (Saxicola rubetra), and Western Yellow Wagtail (Motacilla flava). We banded 3,457 nestlings, including 1,363 Booted Warblers, 1,699 Whinchats, and 395 Western Yellow Wagtails, and resighted 12 Booted Warblers, 29 Whinchats, and 13 Western Yellow Wagtails in the year after fledging. We evaluated first-year apparent survival rates using Cormack-Jolly-Seber models in MARK program within the multispecies approach. We tested effect of fledge date on the first-year apparent survival. In all focal species, first-year apparent survival rates were low and reached the lower limits known for migratory passerines. We found no differences in first-year survival rates among the 3 species: the estimated average first-year apparent survival rate of all species was 0.05 ± 0.01. The fledge date had a considerable impact on first-year survival rate: later fledge dates negatively affected first-year survival. We suggest that first-year apparent survival rates in our study were low due to low natal philopatry and high mortality in the post-fledging period. Low apparent first-year survival may be a specific feature of open-nesting birds breeding in abandoned fields that are low-quality habitats because of high predation pressure.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 7"},"PeriodicalIF":2.4,"publicationDate":"2020-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46428703","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}

{"title":"Defining catchment origins of a geographical bottleneck: Implications of population mixing and phenological overlap for the conservation of Neotropical migratory birds","authors":"Laura Cárdenas-Ortíz, Nicholas J. Bayly, K. Kardynal, K. Hobson","doi":"10.1093/condor/duaa004","DOIUrl":"https://doi.org/10.1093/condor/duaa004","url":null,"abstract":"ABSTRACT Migratory bottlenecks concentrate individuals and populations of Nearctic–Neotropical migrants from across vast breeding areas. The extent to which such concentrations occur has important ramifications for interpreting migratory connectivity and for the vulnerability of populations throughout the annual cycle but investigations of such phenomena are rare. We inferred breeding origins of 11 species of Nearctic–Neotropical migrants captured during fall migration in the Darién region, northwestern Colombia, using feather stable-hydrogen isotope values (δ2Hf). Our objectives were to determine (1) the extent to which this region acts as a catchment for individuals from across a species′ breeding range, (2) if temporal patterns of arrival arise as a function of migration distance inferred from δ2Hf, and (3) if phenological differences among species segregate populations. The Darién concentrated populations of 6 species, with individuals potentially derived from 78% to 94% of their respective North American breeding ranges. The catchment area for the remaining 5 species covered 40–72% of breeding ranges, with a bias in origin from the west (e.g., Northern Waterthrush [Parkesia noveboracensis], Swainson′s Thrush [Catharus ustulatus]), north or center (Yellow Warbler [Setophaga petechia]) of their range. Differential timing in the migration of populations occurred in 6 species, generating a degree of temporal segregation. In contrast, peak migration for all species occurred in October, resulting in high overlap among species in their use of the Darién. Overall, our results describe high mixing of populations in the Darién for several species, which, given the region′s highly restricted geographic extent, suggests that a bottleneck effect occurs; however, comparisons with other regions in Central America and northern South America are required. The combination of extensive population mixing and limited temporal segregation over a narrow geographical area suggests that long-distance migrants may be especially vulnerable to events occurring in such regions, including adverse weather conditions and anthropogenic land cover change.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 13"},"PeriodicalIF":2.4,"publicationDate":"2020-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45598896","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}

{"title":"Blue light attracts nocturnally migrating birds","authors":"Xuebing Zhao, Min Zhang, Xianli Che, Fasheng Zou","doi":"10.1093/condor/duaa002","DOIUrl":"https://doi.org/10.1093/condor/duaa002","url":null,"abstract":"ABSTRACT Light pollution is increasing and artificial light sources have great impacts on animals. For migrating birds, collisions caused by artificial light pollution are a significant source of mortality. Laboratory studies have demonstrated that birds have different visual sensitivities to different colors of light, but few field experiments have compared birds′ responses to light of different wavelengths. We used 3 monochromatic lights (red, green, and blue) and polychromatic yellow light to study the impact of wavelength on phototaxis at 2 gathering sites of nocturnally migrating birds in Southwest China. For both sites, short-wavelength blue light caused the strongest phototactic response. In contrast, birds were rarely attracted to long-wavelength red light. The attractive effect of blue light was greatest during nights with fog and headwinds. As rapid urbanization and industrialization cause an increase in artificial light, we suggest that switching to longer wavelength lights is a convenient and economically effective way to reduce bird collisions.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 12"},"PeriodicalIF":2.4,"publicationDate":"2020-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41644131","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}

{"title":"African sunbirds predominantly pollinate plants useful to humans","authors":"W. Newmark, V. Mkongewa, Debra L Amundsen, Chad Welch","doi":"10.1093/condor/duz070","DOIUrl":"https://doi.org/10.1093/condor/duz070","url":null,"abstract":"ABSTRACT Birds provide multiple ecological services that benefit humans including pollination. In Africa, sunbirds are the dominant vertebrate pollinator. Here we present a species-level assessment for African sunbirds of the number and relative frequency of their food plants that have useful properties to humans. We conducted this analysis by compiling and integrating known sunbird food plants with useful tropical plant and tropical cultivated plant databases. Across Africa, 68% of the 329 genera and 44% of the 468 species of sunbirds′ known food plants are used by humans for medicine, food, building materials, or other uses. Yet most genera and species of useful plants are visited by a small number of sunbird species. The median number of sunbird species that visit a useful genus and species of plant is two and one, respectively. Of the 409 genera and 308 species of useful plants that are sunbird pollinated across one or more of the six predominant habitats for sunbirds, 67% of genera and 71% of species are pollinated by sunbird species that are forest or woodland dependent. Additionally, 58% of all genera and 83% of all species of useful plants pollinated by sunbirds are non-cultivated. In Africa, non-cultivated sunbird-pollinated useful plants are almost entirely collected, used, and traded locally rather than regionally or internationally. Our results indicate that African sunbirds provide important ecological services as pollinators that benefit humans, and these services are provided largely at a local scale. Given the decline of invertebrate and vertebrate pollinators both globally and in Africa, sunbirds are important to the long-term conservation of many useful plants in Africa and hence human well-being.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 9"},"PeriodicalIF":2.4,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz070","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41797256","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}

{"title":"Mountain Plover habitat selection and nest survival in relation to weather variability and spatial attributes of black-tailed prairie dog disturbance","authors":"Courtney J. Duchardt, Jeffrey L. Beck, D. Augustine","doi":"10.1093/condor/duz059","DOIUrl":"https://doi.org/10.1093/condor/duz059","url":null,"abstract":"ABSTRACT Habitat loss and altered disturbance regimes have led to declines in many species of grassland and sagebrush birds, including the imperiled Mountain Plover (Charadrius montanus). In certain parts of their range Mountain Plovers rely almost exclusively on black-tailed prairie dog (Cynomys ludovicianus) colonies as nesting habitat. Previous studies have examined Mountain Plover nest and brood survival on prairie dog colonies, but little is known about how colony size and shape influence these vital rates or patterns of habitat selection. We examined how (1) adult habitat utilization, (2) nest-site selection, and (3) nest success responded to a suite of local- and site-level variables on large prairie dog colony complexes in northeastern Wyoming. Abundance of adult Mountain Plovers was highest on points within older, “medium”-sized (100–500 ha) colonies with high cover of annual forbs and bare ground (5.8 birds km–2), but lower on extremely large (>2,000 ha) colonies (2.1 birds km–2). Nest sites were characterized by high proportions of annual forbs and bare ground and low cactus cover and vegetation height. Nest survival was higher for older nests, and nests with lower cactus cover, and decreased with increasing temperatures. Uncertainty was high for models of daily nest survival, potentially because of 2 competing sources of nest failure: nest depredation and nest abandonment or inviability of eggs. Drivers of these 2 sources of nest failure differed, with inclement weather and higher temperatures associated with nest abandonment or egg inviability. We highlight how prairie dogs alter vegetation structure and bare ground heterogeneously across the landscape, and how this in turn influences bird abundance and nest distribution at different temporal and spatial scales. Furthermore, our work reveals how partitioning the causes of nest failure during nest survival analyses enhances understanding of survival rate covariates.","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 15"},"PeriodicalIF":2.4,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz059","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49279182","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}

{"title":"The Population Ecology and Conservation of Charadrius Plovers","authors":"T. Székely","doi":"10.1093/condor/duaa010","DOIUrl":"https://doi.org/10.1093/condor/duaa010","url":null,"abstract":"","PeriodicalId":50624,"journal":{"name":"Condor","volume":" ","pages":"1 - 2"},"PeriodicalIF":2.4,"publicationDate":"2020-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duaa010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46041718","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}

{"title":"Feather mercury increases with feeding at higher trophic levels in two species of migrant raptors, Merlin (<i>Falco columbarius</i>) and Sharp-shinned Hawk (<i>Accipiter striatus</i>).","authors":"Edward R Keyel, Matthew A Etterson, Gerald J Niemi, David C Evers, Christopher R DeSorbo, Joel C Hoffman, John W Nichols, Yang Li, Frank Nicoletti","doi":"10.1093/condor/duz069","DOIUrl":"10.1093/condor/duz069","url":null,"abstract":"<p><p>Mercury (Hg) is a toxic heavy metal that, when methylated to form methylmercury (MeHg), bioaccumulates in exposed animals and biomagnifies through food webs. The purpose of this study was to assess Hg concentrations in raptors migrating through the upper midwestern USA. From 2009 to 2012, 966 raptors of 11 species were captured at Hawk Ridge, Duluth, Minnesota, USA. Breast feathers were sampled to determine the concentration of total Hg. Mean Hg concentrations ranged from 0.11 to 3.46 μg g^-1 fresh weight across species and were generally higher in raptors that feed on birds in comparison with those that feed on mammals. To evaluate the effect of dietary sources on Hg biomagnification, carbon and nitrogen stable isotope ratios were measured in feathers of the 2 species with the highest Hg concentrations, Merlin (<i>Falco columbarius</i>) and Sharp-shinned Hawk (<i>Accipiter striatus</i>). Measured δ ¹³C values were similar in both species and indicated a primarily terrestrial-derived diet, whereas δ ¹⁵N values suggested that individual Merlin and Sharp-shinned Hawk feeding at higher trophic levels accumulated higher concentrations of Hg. The risk to birds associated with measured levels of feather Hg was evaluated by calculating blood-equivalent values using an established algorithm. Predicted blood values were then compared to heuristic risk categories synthesized across avian orders. This analysis suggested that while some Merlin and Sharp-shinned Hawk were at moderate risk to adverse effects of MeHg, most of the sampled birds were at negligible or low risk.</p>","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1-17"},"PeriodicalIF":2.6,"publicationDate":"2020-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11363152/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44125970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pinniped predation of birds: A cause for conservation concern?","authors":"George J. F. Swan, Eduardo A. Silva‐Rodríguez, L. Osman, E. Jaramillo","doi":"10.1093/condor/duz068","DOIUrl":"https://doi.org/10.1093/condor/duz068","url":null,"abstract":"ABSTRACT Recovering predators can create challenges for conservation objectives when they prey on vulnerable species. Although largely uncommon, pinniped predation of birds presents one such challenge. Here, we describe the novel characteristics of this predator–prey interaction, its impact on bird populations, and possible mitigation responses. We do so both broadly, synthesizing the wider literature, and specifically, in reference to ongoing South American sea lion (Otaria flavescens) predation of Black-necked Swans (Cygnus melancoryphus) we are currently observing in southern Chile. Our review of the literature suggests that in most cases bird predation by pinnipeds is only exhibited by a small proportion of the population, spreads socially between individuals, can be temporally severe, and may rapidly threaten the viability of bird populations. We discuss feasibility and efficacy of potential mitigation measures highlighting that, as foraging specializations can be socially transmitted, any such actions need to be time conscious as bird-killing behaviors may be increasingly difficult to remove. The contrasting population trends of pinnipeds and seabirds suggests that pinniped predation of vulnerable waterbirds is going to be an increasingly common conservation challenge in the future.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 7"},"PeriodicalIF":2.4,"publicationDate":"2020-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz068","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46296781","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}

{"title":"Barn Swallow (Hirundo rustica) fledglings use crop habitat more frequently in relation to its availability than pasture and other habitat types","authors":"Chloe K. Boynton, N. Mahony, T. Williams","doi":"10.1093/condor/duz067","DOIUrl":"https://doi.org/10.1093/condor/duz067","url":null,"abstract":"ABSTRACT Populations of birds that forage on aerial insects have been declining across North America for several decades, but the main causes of and reasons for geographical variation in these declines remains unclear. We examined the habitat use and survival of post-fledging Barn Swallows (Hirundo rustica) near Vancouver, British Columbia, Canada, using VHF radio telemetry. We predicted that fledgling Barn Swallows hatched in higher-quality natal habitat (pasture) would fledge at higher quality, stay closest to the nest, disproportionately use higher-quality habitat during the post-fledge stage, and have higher survival rates in the region. Contrary to our predictions, we found that natal habitat (crop, pasture, or non-agriculture) had no effect on fledgling quality or movement distance. Barn Swallow fledglings used crop habitat more frequently in relation to its availability than other habitat types, including pasture. Barn Swallows had low post-fledging survival rates (0.44; 95% CI: 0.35–0.57), which could negatively influence the population trend of the species in this region. While natal habitat had only minor effects, crop habitat appears to be important for fledgling Barn Swallows and, therefore, a decline in this habitat type could have further negative implications for an already declining species.","PeriodicalId":50624,"journal":{"name":"Condor","volume":"122 1","pages":"1 - 14"},"PeriodicalIF":2.4,"publicationDate":"2020-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/condor/duz067","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42418758","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}