Xcel Energy Inc. has canceled a $400 million wind farm in southeastern North Dakota that potentially threatened two endangered birds.

Under federal law, Xcel would be required to mitigate threats to the whooping crane and the piping plover, a step that carried "uncertainty in the cost and timing," the company said in a regulatory filing Friday.

Xcel said it terminated a 2008 agreement with EnXco Development Corp. to construct the 150-megawatt Merricourt Wind Project in Dickey and McIntosh counties. The project was to have been completed this year.

"We are glad that they made the decision," said Robert Johns, a spokesman for the American Bird Conservancy, which has raised concern about an estimated 440,000 birds killed each year by wind farms.

The whooping crane, the tallest bird in North America, is down to 400 in the wild, according to the U.S. Fish and Wildlife Service. The piping plover is listed as endangered in the Great Lakes area, with just 63 known nesting pairs in 2008.