DNA sequences of the mitochondrial control region were analysed from 298 individual sharp-shinned hawks (Accipiter striatus velox) sampled at 12 different migration study sites across North America. The control region proved to be an appropriate genetic marker for identification of continental-scale population genetic structure and for determining the historical demography of population units. These data suggest that sharp-shinned hawks sampled at migration sites in North America are divided into distinct eastern and western groups. The eastern group appears to have recently expanded in response to the retreat of glacial ice at the end of the last glacial maximum. The western group appears to have been strongly effected by the Holocene Hypsithermal dry period, with molecular evidence indicating the most recent expansion following this mid-Holocene climatic event 7000–5000 years before present.