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

dc.contributor.authorMcKinnon, Emily A.
dc.contributor.authorStanley, Calandra Q.
dc.contributor.authorFraser, Kevin C.
dc.contributor.authorMacPherson, Maggie M.
dc.contributor.authorCasbourn, Garth
dc.contributor.authorMarra, Peter P.
dc.contributor.authorStudds, Colin E.
dc.contributor.authorDiggs, Nora
dc.contributor.authorStutchbury, Bridget J.M.
dc.description.abstractMiniaturized 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.en_US
dc.description.sponsorshipWe thank the following sources of funding: Natural Sciences and Engineering Research Council of Canada, National Geographic Society, Schad Foundation, Kenneth G. Molson Foundation, U.S. Fish and Wildlife Service Neotropical Migratory Bird Grant, Environment Canada, York University, proceeds from Silence of the Songbirds (2007, Walker & Co.). We thank the many dedicated field assistants and volunteers for help with deployment and retrieval of geolocators at multiple sites across North and Central America.en_US
dc.format.extent8 pagesen_US
dc.genrejournal articlesen_US
dc.identifier.citationEmily A. McKinnon, Calandra Q. Stanley,, Animal Migration, Volume 1, Pages 31–38, ISSN (Online) 2084-8838, DOI:
dc.publisherWalter de Gruyter GmbHen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Geography and Environmental Systems Department
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rightsAttribution-NonCommercial-NoDerivs 3.0 United States*
dc.subjectsun elevationen_US
dc.subjectCentral Americaen_US
dc.titleEstimating geolocator accuracy for a migratory songbird using live ground-truthing in tropical foresten_US


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