American white pelican chicks enjoyed a better year at Chase Lake National Wildlife Refuge this summer.

Only 12 percent, or about 1,300 chicks, of the estimated 11,000 young birds died this summer, said Ken Torkelson, a U.S. Fish and Wildlife Service spokesman in Bismarck.

"It's a big improvement. In the previous two years, we had virtually nothing, and when the West Nile virus first showed up, we lost between 40 percent and 50 percent," Torkelson said.

Three chicks sent to a laboratory for necropsies came back positive for West Nile, Torkelson said.

"We assume it was West Nile. We had no weather events or predation," Torkelson said.

Researchers speculated that the dry weather may have cut back on mosquitoes, which transmit the disease.

The pelicans already have begun their southern migration from the refuge north of Medina, Torkelson said.

Two years ago, adult pelicans mysteriously abandoned their nests, leaving behind chicks and eggs, neither of which survived. Last year, the bulk of the chick population died, and adult pelicans pulled out of the colony.

"It's a relief. We feel good about it," Torkelson said. "Does this mean we will have no problems with the pelicans at Chase Lake? Probably not, but we will take successes as we get them."

(Reach outdoor writer Richard Hinton at 701-250-8256 or richard.hinton@;bismarcktribune.com.)