Back on January 15th, US Airways Flight 1549 made that amazing water landing in the Hudson after both engines were taken out by Canada geese, which can weigh eight pounds each. Now scientists have used forensic techniques to clear local geese—the perpetrators were out-of-towners. The study appears June 8th in the journal Frontiers in Ecology and the Environment.

Crash investigators sent feather samples from the plane’s engines to the Smithsonian, which has a dedicated Feather Identification Lab. The researchers examined the feather’s hydrogen isotopes, which include regular hydrogen atoms and hydrogens with additional neutrons. The isotope ratios tell you about the bird’s diet. And that tells you where they dined.

The analysis showed that the birds that hit the plane were much closer to geese migrating from Canada’s Labrador region than the geese who live year-round in New York. That info could be important for strategies to avoid future bird strikes. The usual techniques for keeping resident birds away from planes are still working—but we need ones for strangers just passing through.

—Steve Mirsky