Figure 1.

Migration routes and wintering grounds of three northern wheatears breeding in Alaskan (AK) and one in the eastern Canadian Arctic (CN; grey dot, breeding area, blue, autumn migration, orange, spring migration, dashed lines indicate uncertainty in migration routes close to equinoxes). Fifty per cent kernel densities of winter fixes (beginning of December 2009–end of February; purple, bird AK-1; green, bird AK-2; orange, bird AK-3; blue, bird CN-1) are given depending on the sun elevation selected (with −2° for most southern and with −4.5° for most northern densities). Pie charts indicate the proportion of individuals (AK: n = 9, CN: n = 4) originating from one of the three pre-defined wintering regions (red, western; orange, central; yellow, eastern) [8] based on stable-hydrogen isotope (δD) values in winter grown feathers and the δD values within each wintering region (mean ± s.d. shown).