Pelican Scare : Hundreds of Dead, Dying Birds Raise Alarm in Eastern Sierra

Several hundred white pelicans have been found dead or dying beside eastern Sierra lakes and streams that supply drinking water to Los Angeles, leaving state and federal wildlife officials mystified and concerned.

The unusual die-off of the large migratory birds is no threat to the water supply, they stressed. But tests are being conducted to see if something in the water could be causing the deaths.

Although the white pelicans--cousins of the brown pelicans found on the California coast--nest over a wide area of the West, the trouble seems confined to the eastern Sierra.

“We don’t know the cause of the mortality,” said Vern Bleich, wildlife biologist with the California Department of Fish and Game.

Most Found at Crowley

Most of the pelicans have been found during the last three weeks at Crowley Lake, a reservoir and popular fishing lake run by the Los Angeles Department of Water and Power north of Bishop. Carcasses and stricken birds also have been found farther south along the Owens River and at Tinemaha and Haiwee reservoirs, part of the city’s vast Owens Valley waterworks.

Preliminary tests have found an unusually high number of parasitic worms in the walls of the stomachs of nearly all the birds, said David Jessup, a state veterinarian and pathologist in Sacramento. There were signs of malnutrition that could be explained by the worms, but the birds did not appear to have starved, he said.

Jessup said, however, that many other causes cannot yet be ruled out. No significant pesticide residue has been found, but more detailed tests will be made to see if the pelicans had ingested high levels of toxic metals, he said.

Certain metals and chemicals have been held responsible for large-scale bird deaths elsewhere in California. Selenium-tainted water that ran off agricultural fields is blamed for killing waterfowl at the Kesterson Wildlife Refuge in the San Joaquin Valley. Jessup said that selenium tests had not yet been completed on the pelicans.

State officials are sufficiently alarmed to have requested this week that more carcasses be sent to Sacramento for study in a Fish and Game Department laboratory.

High levels of iron and zinc were found in the first Owens Valley pelicans tested, but those metals are not ordinarily considered toxic, Jessup said. “We don’t know quite what to make of it,” he said Wednesday.

White pelicans do not usually breed beside Crowley and the Owens Valley waterways, preferring instead lakes and wetlands farther north.

A large breeding population is found at the Klamath Basin wildlife refuge near the California-Oregon border, and a smaller group nests on Anaho Island in Nevada’s Pyramid Lake northeast of Reno.

The Pyramid Lake colony suffered a very low nesting rate last spring, perhaps because of a third winter of low snowmelt into the Truckee River. But the Klamath Basin pelicans, the only breeding colony in California, seem to be thriving.

No Problem at Refuge

“We haven’t seen anything out of the ordinary up here at all,” said Jim Hainline, wildlife biologist at the Klamath Basin refuge.

No identifying bands have been found that would allow the carcasses to be traced, state biologists said. Most white pelicans migrate to Mexico in the fall. The birds found at Crowley Lake and in the Owens Valley may have been on their annual migration, biologists said.

Crowley’s water level is exceptionally low this fall, in part because of a dearth of rain and snowfall and in part because of a court order requiring that water normally diverted into the lake be released instead into Mono Lake.

As the water level at Crowley falls, concern has grown among anglers and some officials that pelicans are eating too many trout trying to spawn upstream in the lake. The pelicans have been blamed by some people in the area for depleting the trout. However, biologists said there are no indications that the pelicans were deliberately poisoned.