At about 1500 on Monday, 27 September 1982, Webster was birding at the San Diego River mouth, San Diego County, California. He was standing on the south side of the flood control channel, viewing the flats through a 15–25× spotting scope, when he noted an unusual tern about 50 yards away. It flew with steady, rowing wingbeats, rising and falling a bit on every stroke, as it headed into the stiff breeze coming off the ocean. After a rainy morning, the sun was out, though winds were still gusting to 20 miles per hour