With only one breeding trumpeter swan pair left in park, Yellowstone biologists resort to “grafting”
JACKSON, Wyo. (AP) — A trio of sprightly two-day-old cygnets hears their new foster parents calling nearby. Instinctively, the young, captive-raised swans jump off a platform and paddle into the chilly waters of Yellowstone National Park's Grebe Lake.
This is a swan "graft," an effort to trick the two adult swans into raising the three young now swimming toward them.