Similar to Bewick's Swans (Eurasian race of Tundra Swan), this species is decidedly larger and has a more extensive yellow patch on its bill. Unlike Bewick's this patch extends to a point under and beyond the nostril forming a triangle. We found them to be more common in Hokkaido than in Honshu. Here they were actively hazed and chased away ostensibly to avoid being a disease vector which might impact the Red-crowned Cranes. A recent study confirmed that this species may transmit H5N1 influenza from one part of its range to another (China to Mongolia) Some authors lump this species with the Trumpeter Swan of North America.
