Browsing by Author "McKinnon, Emily A."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Connectivity of wood thrush breeding, wintering, andmigration sites based on range-wide tracking(Society for Conservation Biology, 2014-07-22) Stanley, Calandra Q.; McKinnon, Emily A.; Fraser, Kevin C.; Macpherson, Maggie P.; Casbourn, Garth; Friesen, Lyle; Marra, Peter P.; Studds, Colin; Ryder, T. Brandt; Diggs, Nora E.; Stutchbury, Bridget J. M.Many migratory animals are experiencing rapid population declines, but migration data withthe geographic scope and resolution to quantify the complex network of movements between breedingand nonbreeding regions are often lacking. Determining the most frequently used migration routes andnonbreeding regions for a species is critical for understanding population dynamics and making effectiveconservation decisions. We tracked the migration of individual Wood Thrushes(Hylocichla mustelina)(n=102) from across their range with light-level geolocators and, for the first time, quantified migration routesand wintering regions for distinct breeding populations. We identified regional and species-level migratoryconnectivity networks for this declining songbird by combining our tracking results with range-wide breedingabundance estimates and forest cover data. More than 50% of the species occupied the eastern winteringrange (Honduras to Costa Rica), a region that includes only one-third of all wintering habitat and that isundergoing intensive deforestation. We estimated that half of all Wood Thrushes in North America migratesouth through Florida in fall, whereas in spring approximately 73% funnel northward through a narrow spanalong the central U.S. Gulf Coast (88–93°W). Identifying migratory networks is a critical step for conservationof songbirds and we demonstrated with Wood Thrushes how it can highlight conservation hotspots for regionalpopulations and species as a wholeItem Estimating geolocator accuracy for a migratory songbird using live ground-truthing in tropical forest(Walter de Gruyter GmbH, 2013-02-06) McKinnon, Emily A.; Stanley, Calandra Q.; Fraser, Kevin C.; MacPherson, Maggie M.; Casbourn, Garth; Marra, Peter P.; Studds, Colin E.; Diggs, Nora; Stutchbury, Bridget J.M.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 (OctDec) 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.