BIODIVERSITY RESEARCH Topography of the Andes Mountains shapes the wintering distribution of a migratory bird Ana M. Gonz alez-Prieto 1,2 *, Nicholas J. Bayly 2 , Gabriel J. Colorado 3 and Keith A. Hobson 1,4,5 1 Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK, S7N 5E2, Canada, 2 SELVA: Investigaci on para la Conservaci on en el Neotr opico, Bogot a, Colombia, 3 Universidad Nacional de Colombia sede Amazonia, km 2 v  ıa Tarapac a, Leticia, Colombia, 4 Environment Canada, 11 Innovation Boulevard, Saskatoon, SK, S7N 5H5, Canada, 5 Department of Biology, University of Western Ontario, 1151 Richmond St. N, London, ON, N6A 5B7, Canada *Correspondence: Ana M. Gonz alez-Prieto, Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK S7N 5E2, Canada. E-mail: ana.gonzalez@usask.ca ABSTRACT Aim In birds, patterns of migratory connectivity are influenced by landscape structure experienced throughout the annual cycle. Assessing how landscape patterns drive the movements and distributions of migratory species is impor- tant for understanding the evolution of migration and determining conserva- tion priorities. We determined migratory connectivity in the Canada Warbler (Cardellina canadensis), a declining Neotropical migratory bird, and evaluated the degree to which the Andean mountains influence winter population distri- bution in this montane forest specialist. Location Seven study regions across the Western, Central, and Eastern Andes of Colombia. Methods We inferred breeding and natal origins of Canada Warblers overwin- tering in Colombia by analysing stable hydrogen isotope values (d 2 H) in feath- ers and assigning wintering populations to breeding origins using an established feather d 2 H isoscape for North America. Results We found strong evidence for parallel migration between breeding and wintering sites, giving rise to moderately strong migratory connectivity between breeding and wintering regions. The model best explaining population distribu- tion in the Colombian Andes implied that populations were most similar within basins or valleys. Such segregation is notable, given that basins are sepa- rated by less than 300 km on the wintering grounds, while breeding popula- tions may be separated by more than 3000 km from east to west. Main conclusions Our results suggest that the high spine of each Andean cordil- lera acts to shape the winter distribution of individuals from different breeding populations. To our knowledge, this is the first demonstration that the topography of the Andean mountains can act to shape the winter distribution of populations of a migratory bird. The strength of migratory connectivity found in Canada Warblers may inhibit evolutionary responses to environmental change, and the more rapid population declines recorded in some eastern breeding populations may be related to habitat loss and local environmental conditions in the Eastern Andes, where individuals from these populations were more likely to overwinter. Keywords Canada Warbler, Cardellina canadensis, Colombia, deuterium, isoscapes, migratory connectivity, stable isotopes. INTRODUCTION Mountains have long been recognized both as barriers and as insular environments that shape the distribution and population structure of countless organisms (Vuilleumier, 1969; Ruggiero & Hawkins, 2008). Indeed, montane habitats have been equated to islands, giving rise to speciation or divergence between populations inhabiting isolated mountain DOI: 10.1111/ddi.12515 ª 2016 John Wiley & Sons Ltd http://wileyonlinelibrary.com/journal/ddi 1 Diversity and Distributions, (Diversity Distrib.) (2016) 1–12 A Journal of Conservation Biogeography Diversity and Distributions