Tuesday, October 26, 2010

Yosemite Great Grays from the Ice Age

Recent genetic analysis shows that the Great Gray Owls of Yosemite National Park are a subspecies stranded by the last Ice Age rather than a remnant chased out of northern California by logging and development.

The Yosemite owl is not only genetically different from great gray owls in Oregon, Idaho and Canada, it also nests slightly differently and prefers a more narrow diet of rodents, scientists say.

More than half of California's great gray owls are in the Yosemite region, and there are very few between the park and southern Oregon. Scientists say they still do not understand why there are only a few great grays in Northern California forests.

It is not unusual to find species in the Sierra that were stranded during the last Ice Age, said wildlife ecologist John Keane, who led the research for the U.S. Forest Service Pacific Southwest Research Station....

Great gray owls live at an altitude of 4,000 to 8,500 feet in the Sierra, but they migrate to lower elevations in snowy winters or when there is a lack of food.
While other Great Gray populations eat a diverse array of rodents, ones in the Sierra specialize in pocket gophers and voles.

One interesting note is that the researchers are working on a method for finding Great Gray Owl populations. Rather than doing foot searches, they are setting up microphones to record all of the sounds of a meadow for a week at a time. The sounds are analyzed by computer to detect owls.