{"title":"Population Trends of the Ferruginous Hawk (Buteo regalis) Wintering in California","authors":"Edward R. Pandolfino, L. Douglas, Chris Ray","doi":"10.3356/jrr2370","DOIUrl":null,"url":null,"abstract":"\n The Ferruginous Hawk (Buteo regalis) is a raptor of conservation concern in much of its range. Population trend estimates from Breeding Bird Surveys and migration counts for this species are often contradictory and of low credibility. Therefore, we used Christmas Bird Count data to assess population trends for Ferruginous Hawks that winter in California, USA. Evidence suggests that the birds breeding in southeastern Washington and northeastern Oregon may represent a metapopulation that winters almost exclusively in California. Data for the 25-yr period from Count Year 98 (winter 1997–1998) to Count Year 122 (winter 2021–2022) from 22 California Christmas Bird Count circles in the core winter range of Ferruginous Hawks showed a significant positive trend. This positive trend contrasts with the continent-wide negative trends observed for most grassland/open country bird species and is surprising given ongoing declines of this species’ preferred winter habitat in California during this same period. We discuss potential explanations that may account for these differences, including the possibility that the California-wintering Ferruginous Hawks include a large proportion of birds breeding outside of southeastern Washington and northeastern Oregon.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":null,"pages":null},"PeriodicalIF":1.2000,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Raptor Research","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.3356/jrr2370","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ORNITHOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
The Ferruginous Hawk (Buteo regalis) is a raptor of conservation concern in much of its range. Population trend estimates from Breeding Bird Surveys and migration counts for this species are often contradictory and of low credibility. Therefore, we used Christmas Bird Count data to assess population trends for Ferruginous Hawks that winter in California, USA. Evidence suggests that the birds breeding in southeastern Washington and northeastern Oregon may represent a metapopulation that winters almost exclusively in California. Data for the 25-yr period from Count Year 98 (winter 1997–1998) to Count Year 122 (winter 2021–2022) from 22 California Christmas Bird Count circles in the core winter range of Ferruginous Hawks showed a significant positive trend. This positive trend contrasts with the continent-wide negative trends observed for most grassland/open country bird species and is surprising given ongoing declines of this species’ preferred winter habitat in California during this same period. We discuss potential explanations that may account for these differences, including the possibility that the California-wintering Ferruginous Hawks include a large proportion of birds breeding outside of southeastern Washington and northeastern Oregon.
期刊介绍:
The Journal of Raptor Research (JRR) is an international scientific journal dedicated entirely to the dissemination of information about birds of prey. Established in 1967, JRR has published peer-reviewed research on raptor ecology, behavior, life history, conservation, and techniques. JRR is available quarterly to members in electronic and paper format.