December 29, 2005

Tiny American pika seen headed toward extinction

WASHINGTON (Reuters) - Human activity and climate change
may be pushing the tiny American pika toward extinction in the
mountains of western North America, according to research
published on Thursday.

The small rabbit-like mammals live in rock-strewn slopes
but are gradually being pushed to higher elevations and are
running out of places to live, archeologist Donald Grayson
reports in the current issue of the Journal of Biogeography.

"Human influences have combined with factors such as
climate change operating over longer time scales to produce the
diminished distribution of pikas in the Great Basin today,"
Grayson said.

Seven of 25 historically described populations of pikas in
the Great Basin -- the area between the Sierra Nevada and Rocky
Mountains -- appear to have become extinct by the end of the
20th century, Grayson said.

Among the intrusions that appear to imperil the pikas are
roads built close to their habitat and pressure from grazing
livestock, Grayson said.

He examined 57 archeological sites dating as far back as
40,000 years, as well as unpublished studies by other
researchers, finding that the tiny mammals have been pushed
higher over the years.

"The Great Basin pika is totally isolated on separated
mountain ranges and there is no way one of these populations
can get to another," Grayson said in a statement. "They don't
have much up-slope habitat left."

Pikas, which are very sensitive to high temperatures, are
considered to be one of the best early warning systems for
detecting global warming in the western United States, the
journal reported.