Anim. Migr. 2016; 3: 48–56 1 Introduction Understanding migratory connectivity patterns is a critical component to the conservation of migratory birds and to understanding the consequences of habitat loss and climate change on biodiversity [1,2]. By identifying a species’ migratory geography, we can increase our knowledge of the factors that limit populations, and in which season(s) of their annual cycle the limitations occur [3,4]. Additionally, determining the strength of migratory connectivity can highlight which populations may be most vulnerable: populations that have strong migratory connectivity (e.g., individuals that spend the breeding season in one area also spend the winter season in close proximity to one another) may be most sensitive to perturbations because there are fewer individuals from other areas to buffer impacts from disturbances that occur during any part of their annual cycle [5]. Recently, the proliferation of geolocator studies has dramatically increased our knowledge of where migratory passerines go throughout their annual cycle, and of their migratory connectivity [6,7,8]. These studies have provided insight at a scale that has not been available from other methods, including the ability to assess migratory connectivity patterns of populations wintering or breeding close to one another. For example, with a relatively small sample size, Nelson et al. [9] demonstrated that Hermit Thrushes (Catharus guttatus) on the north side of San Francisco Bay in California migrate to different locations than those that winter on the south side of San Francisco Bay. Hence, on the wintering grounds, the proportion of individuals from different breeding populations may change dramatically across relatively short distances and as a result, conservation needs of a species could also vary within a small spatial scale. Golden-crowned Sparrows (Zonotrichia atricapilla) breed from Alaska, USA to southern British Columbia and Alberta, Canada, and winter from British Columbia to northern Baja California, Mexico [10]. Their migratory ecology has not been well-studied, and there are no recognized subspecies [10]. Recent work has demonstrated that across their breeding range, Golden-crowned DOI 10.1515/ami-2016-0005 Received April 20, 2016; accepted August 3, 2016 Abstract: Knowledge of migratory connectivity is critical to understanding the consequences of habitat loss and climate change on migratory species. We used light-level geolocators to determine breeding locations and migratory routes of wintering Golden-crowned Sparrows (Zonotrichia atricapilla) in two regions of California, USA. Eight out of 9 birds tagged at coastal-wintering sites in Marin County went to breeding sites along the Gulf Coast of Alaska, while 7 out of 8 inland-wintering birds in Placer County migrated to interior sites in the Yukon, Northwest Territories, and British Columbia, Canada. Our estimate of the strength of migratory connectivity was relatively high (r m = 0.66). Coastal-wintering birds followed a coastal migration route while inland-wintering birds migrated inland. Coastal- wintering birds migrated significantly farther than inland birds (3,624 km versus 2,442 km). Coastal birds traveled at a greater rate during spring migration (179 km/d) than did inland birds (118 km/d), but there was no statistical difference in the rate of fall migration (167 km/d and 111 km/d, respectively). Dates of arrival and departure, and duration of spring and fall migration, did not differ between groups, nor did return rates. Rates of return also did not differ between tagged and control birds. The distinct migration routes and breeding areas suggests that there may be more structuring in the migratory geography of the Golden-crowned Sparrow than in a simple panmictic population. Keywords: Light-level geolocation, migratory divide, migratory route, rate of migration, Zonotrichia atricapilla, wintering grounds Research Article Open Access © 2016 Renée L Cormier et al., published by De Gruyter Open. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License. Renée L Cormier, Diana L Humple, Thomas Gardali, Nathaniel E Seavy Migratory connectivity of Golden-crowned Sparrows from two wintering regions in California *Corresponding author Renée L Cormier, Point Blue Conservation Science Petaluma, CA, United States, E-mail: rcormier@pointblue.org Diana L Humple, Thomas Gardali, Nathaniel E Seavy, Point Blue Conservation Science, 3820 Cypress Drive #11, Petaluma, CA 94954, CA, United States - 10.1515/ami-2016-0005 Downloaded from PubFactory at 08/30/2016 12:36:34AM via free access