With more than 1,000 pairs of gulls nesting on the new island in Crump Lake, the terns have had some difficulty protecting their eggs from the more aggressive and voracious gulls, Roby said. The nesting season peaks in mid-June and the researchers hope to see some chicks emerge within the next 2-3 weeks.
There also is the obvious question about what comprises the terns' diet at Crump Lake. Most of the birds there are eating bullheads and the small, but abundant tui chubs the same species of fish illegally introduced into Diamond Lake, prompting state officials to poison the lake to get rid of them. Tui chubs are native to Crump Lake and provide a stable food supply for a variety of fish-eating birds, including terns.
OSU researchers and the Corps have built a blind on the island and are using it to study the Caspian terns, cormorants and gulls while avoiding the possibility of disturbing the nesting birds. Already they have spotted terns that researchers banded during previous studies. These bands reveal that some of the terns came from East Sand Island and Rice island in the Columbia River estuary, while others originated from Potholes Reservoir near Moses Lake, Wash., and Crescent Island, near Pasco, Wash.
"We are encouraged by the observation of birds from multiple locations," Dorsey said. "They help prove that terns can be attracted to alternative locations, away from the Columbia River estuary."
The goal of the project, Roby reiterated, is not to reduce the overall number of Caspian terns in the region an estimated 13,000 to 14,000 nesting pairs. It simply is to redistribute the population to lessen their impact on the survival of juvenile salmon from the Columbia River Basin. Research revealed, for example, that a single colony of 500 pairs of Caspian terns consumed one-third of all the Snake River juvenile steelhead that attempted to migrate past the tern colony during a drought year.
"The key to
|Contact: Dan Roby|
Oregon State University