The federal government has charged PacifiCorp and Exxon Mobil Corp. in two unrelated cases with killing scores of migratory birds in Wyoming, according to court documents filed last week in U.S. District Court in Cheyenne.

PacifiCorp, which does business in Wyoming as Rocky Mountain Power, is charged in a 34-count criminal information document with the deaths of 38 golden eagles at power poles in six counties from December 2007 to February 2009.

Twenty-five of the eagles died in Washakie County, seven in Sweetwater County, two each in Hot Springs and Park counties, and one each in Converse and Natrona counties, according to the information document filed on June 24.

A charge is an allegation until a conviction or guilty plea.

In a separate case, the U.S. attorney's office charged ExxonMobil with the deaths of at least 64 birds including ducks, grebes, passerines and shore birds.

The birds died after contact with hydrocarbons in a disposal facility and evaporation ponds in Sublette and Lincoln counties, according to the criminal information document filed on June 23.

The bird deaths are violations of the Migratory Bird Treaty Act, and are misdemeanors each punishable by up to six months imprisonment and a $15,000 fine.

However, the prison terms are not applicable to corporations.

The ExxonMobil case is part of a group of similar prosecutions involving several federal state districts, said Wyoming Assistant U.S. Attorney Dave Kubichek.

The ExxonMobil cases have been consolidated, he said.

On Wednesday, U.S. District Judge Clarence Brimmer signed an order transferring the case to federal court in Colorado for a guilty plea and sentencing, according to the court docket.

Kubichek emphasized the cases were unrelated.

The PacifiCorp case inadvertently was placed in the public record for a week, Kubichek said. It has since been sealed until the company appears before U.S. Magistrate Judge Michael Shickich to enter a change of plea in federal court in Casper at 2:30 p.m. July 10.

A spokeswoman for ExxonMobil said in a prepared statement that the company has worked in good faith with the U.S. Department of Justice and the U.S. Fish and Wildlife Service to resolve issues about protection of water birds on company property.

"The company has a long-standing water-bird protection program that focuses on deterring birds from landing in water on company property," Margaret Ross said from ExxonMobil headquarters in Houston.

"This program includes various technologies for bird deterrence," Ross said.

"ExxonMobil has extensive operations across the U.S. with bird populations in the millions," she said. "Our upstream operations have reported events involving fewer than 100 birds over the past six years."

A spokeswoman for PacifiCorp made a similar comment about the golden eagle deaths in Wyoming.

"We believe we've reached a resolution with the U.S. attorney and the Fish and Wildlife Service subject to approval by the court," Margaret Oler said.