For the first time in recorded history, Yellowstone
National Park trumpeter swans added no young to their flock last
summer. The decline in cygnets parallels a decrease in the adult
population from almost 500 last year to 277 this year. Ruth Shea,
of the Idaho Fish and Game Department, believes a major cause is
competition between trumpeter swans that summer in Canada and those
that stay year-round. When the more numerous Canadian birds winter
on the Yellowstone region’s geothermal lakes, they may spread
disease and exhaust feeding grounds. To alleviate crowding, Idaho
state biologists are trapping Canadian swans in the winter and
trucking them to warmer areas to the south and west. But
Yellowstone ornithologist Terry McEneaney says moving the birds
could add to the problem. Biologists may inadvertently trap
resident swans, which look similar to Canadian swans. Life isn’t
easy for resident swans; they face harsh winters, lead poisoning,
competition with mute swans introduced on ranches around the park,
as well as flooding and human disturbance of nesting sites. The
Park Service recently outlawed fishing with lead sinkers and
erected signs and barriers to keep the public away from nesting
areas. For more information, contact the Idaho Fish and Game
Department at 208/334-1931 or the National Park Service at
307/344-7381.
This article appeared in the print edition of the magazine with the headline Silent swans in Yellowstone.
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