SISTERS â The most prolific trumpeter swan pair in Oregonâs breeding program experienced a tragic turn of events Saturday when the male, Pete, died from a bacterial infection. Pete and his mate, Eloise, produced 15 young in the past three years from their home at the Aspen Lakes Golf Course in Sisters. The pair was a boost to the stateâs effort to repopulate the threatened species. Eloise is now the second swan in Central Oregon to lose a mate in recent months, after Gracie, the resident swan at Sunriver Nature Center, was killed in October, leaving her mate, Gus. Wildlife officials relied on the two pairs to produce young in the protected environments at the golf course and at the nature center. The babies, or cygnets, were then sent to live in the wild at the Summer Lake Wildlife Area, a 19,000-acre wetland in central Lake County that is ideal wetlands for swans.