Stable nitrogen isotopes in waterfowl feathers reflect agricultural land use in western Canada.

Stable nitrogen and carbon isotope analysis was performed on secondary feathers collected from flightless, mallard ducklings (Anas platyrhynchos) from 17 locations across western Canada. The delta15N values of mallard feathers ranged from +6.1 to +23.7 per thousand (AIR). Mean delta15N feather values from the 17 locations were strongly correlated with the percentage of land under agricultural development. Higher delta15N values in waterfowl feathers collected from agricultural areas possibly reflected the entry of excess fertilizer nitrogen into local water bodies. However, other processes may have also been important. These results provide evidence that nitrogen isotope values in avian feathers may reflect long-term nitrogen additions to surface waters in agricultural areas and may also provide important clues in elucidating the origin of nonpoint source nitrogen inputs.