State wildlife biologists researching the rare Sierra Nevada red fox have been trying to capture one for over a decade. On Tuesday, they caught the second one in three weeks.
A nearly nine-pound female walked into a box trap near Manzanita Lake in Lassen Volcanic National Park. She joins a 10-pound male, captured February 13 on national forest land near Mineral just outside the park boundary. Both animals were released after biologists took blood samples, conducted routine field examinations and equipped them with collars for remote tracking.
Scientists have been trying to better understand the Sierra Nevada red fox since 1980, when it was listed as threatened in California. They intensified their study in 2008 but were not able to capture an animal until now, said Jennifer Carlson, an environmental scientist with the California Department of Fish and Wildlife.
"This is huge," Carlson said.
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Electronic tracking will allow biologists to know more about the size and characteristics of the elusive red fox's home range and how it uses the habitat. They also hope to learn more about its den sites and reproductive rates.
"We know so little about this animal, and we have never found a den – ever," Carlson said.
She described the female as a healthy two-year-old with a beautiful coat. The fox did not appear to have given birth or to be pregnant, Carlson said.
The Sierra Nevada red fox once roamed widely in the upper mountain sub-alpine zones of California's Sierra Nevada and Cascade ranges. A distinct subspecies of red fox, its abundance and distribution has declined dramatically in the last century. In addition to the Lassen population, a group exists at Mt. Bachelor in central Oregon.
Other red foxes in California include the Sacramento Valley red fox, which occupies portions of the Sacramento Valley, and non-native red foxes widespread in low-elevation habitats.
The Sierra Nevada sub-species requires a specific high-elevation habitat that has been shrinking. That may help to explain the decline, said Carlson.
The other principal threat to its future is in-breeding. Carlson estimated there are around 20 individuals in the Lassen group, likely too few to sustain a population under ideal conditions. Scientists are collecting fox scat and hair samples to build a database that will help them understand their genetics and how the individual Lassen foxes are related.
Under better circumstances, they would disperse to other areas where they could mate with genetically distinct animals, said Carlson. The male fox collared last month has already surprised biologists by traveling more than seven straight-line miles a day over territory that included Lassen and adjacent peaks in the national park.
Carlson attributed the recent capture successes to doubling the number of scientific aides working on the Sierra Nevada red fox project. Once they detect animals, they saturate the area with traps to maximize the potential for a capture.
The collars the two animals are now wearing are sophisticated light-weight devices that have just become available in the last two years, said Carlson. They provide location information every three hours.
State Fish and Wildlife biologists hope to capture and collar as many as four red foxes this year. The information will provide significant insights into the habits, health and disease ecology of the sub-species, Carlson said.