Browsing by Author "Studds, Colin"
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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 Migratory birds with delayed spring departure migrate faster but pay the costs(Wiley, 2022-12-01) Dossman, Bryant C.; Rodewald, Amanda D.; Studds, Colin; Marra, Peter P.Migratory birds that experience poor overwintering conditions are often late to arrive at the breeding grounds, which is known to depress individual fitness. Despite the importance of this carryover effect, few studies have investigated how individuals can modify migratory behaviors en route to reduce delays on arrival and whether accelerating migration incurs survival costs. To examine this, we used Motus Wildlife Tracking System to track individual American redstarts (Setophaga ruticilla) as they migrated from wintering grounds in Southwest Jamaica through Florida en route to their breeding areas. We leveraged long-term data on spring departure timing and breeding latitude to quantify the relative departure dates (early vs. delayed) of tagged individuals, which we then related to individual migration rates and apparent annual survival. Compared to those initiating migration earlier, individuals that departed relatively late (10-day delay) migrated at a 43% faster rate which decreased their annual survival by 6.3%. Our results are consistent with the hypothesis that spring migrants use speed to compensate for departure delays despite incurring survival costs. This compensatory behavior may potentially underly differential survival during spring migration and may be particularly widespread across short-lived migratory birds generally considered time-constrained