Estimating geolocator accuracy for a migratory songbird using live ground-truthing in tropical forest

Q2 Agricultural and Biological Sciences
E. McKinnon, Calandra Q. Stanley, K. Fraser, Maggie M. MacPherson, Garth Casbourn, P. Marra, Colin E. Studds, Nora E. Diggs, B. Stutchbury
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引用次数: 37

Abstract

Abstract Miniaturized light-level geolocators allow year-round tracking of small migratory birds, but most studies use calibration only at breeding sites to estimate geographic positions. Ground-truthing of positions in tropical habitat is needed to determine how accurate breeding site calibrations (i.e. sun elevations) are for estimating location of winter sites. We tested the accuracy of geographic assignments using geolocator data collected from Wood Thrushes (Hylocichla mustelina) in Central America. For a given light threshold, sun elevation angle was higher in the tropics than at breeding sites and also varied significantly at tropical winter sites between wet (Oct- Dec) and dry (Jan-Mar) seasons. However, estimation of Wood Thrush territory latitude did not differ significantly when using breeding or tropical dry season sun elevation. Average error in assignment to tropical sites was 365 ± 97 km (0.2-4.4°) in latitude. To obtain the best latitude estimates in the tropics with geolocators, we recommend using locations during the dry season where sun elevations are closer to those measured at breeding sites. We emphasize the importance of longitude in assigning forest birds to unknown sites; longitude estimates for Wood Thrushes in the tropics were, on average, within 66 ± 13 km (0-0.6°) of actual longitude. Latitude estimates were more accurate (180 ± 48 km) when assigning birds to breeding sites using deployments of geolocators in the tropics. Studies of species that are territorial in winter could collect more accurate migratory connectivity data by deploying geolocators at tropical wintering sites.
在热带森林中使用实时地面测深估算候鸟的地理定位精度
小型轻型地理定位器可以全年跟踪小型候鸟,但大多数研究仅在繁殖地进行校准以估计地理位置。需要对热带栖息地的位置进行地面真实测量,以确定繁殖地点校准(即太阳高度)对估计冬季地点位置的准确性。我们使用从中美洲画眉(Hylocichla mustelina)收集的地理定位器数据来测试地理分配的准确性。在光照阈值相同的情况下,热带地区的太阳仰角高于繁殖地,并且在湿润季节(10 - 12月)和干燥季节(1 - 3月)之间,热带地区的太阳仰角也有显著差异。然而,当使用繁殖和热带旱季太阳高度时,对画眉区纬度的估计没有显著差异。热带地点的平均误差为纬度365±97公里(0.2-4.4°)。为了利用地理定位器获得热带地区的最佳纬度估计,我们建议使用旱季太阳高度接近繁殖地点的位置。我们强调经度在给森林鸟类分配未知地点时的重要性;热带地区画眉的经度估计值平均在实际经度66±13公里(0-0.6°)范围内。在热带地区使用地理定位器将鸟类分配到繁殖地时,纬度估计更为准确(180±48公里)。通过在热带越冬地点部署地理定位器,对冬季有领地性的物种的研究可以收集更准确的迁徙连通性数据。
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来源期刊
Animal Migration
Animal Migration Environmental Science-Ecology
CiteScore
3.70
自引率
0.00%
发文量
3
审稿时长
18 weeks
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