Stable isotopes examined across a migratory divide in Scandinavian willow warblers (Phylloscopus trochilus trochilus and Phylloscopus trochilus acredula) reflect their African winter quarters
The C and N isotopes of feathers from two subspecies of willow warblers (Phylloscopus trochilus trochilus and Phylloscopus trochilus acredula) are isotopically distinct. Our analysis of 138 adult males from 14 sites distributed across Sweden shows that the mean delta(15)N and delta(13)C values of subspecies acredula (from latitudes above 63 degrees N) were significantly higher than the mean delta(