Some Good News For Desert Kit Foxes

A second year of surveys of desert kit foxes has failed to reveal continued infection by the distemper virus that killed at least 11 animals in late 2011. That's according to veterinarian Deana Clifford, who's been tracking the outbreak for the California Department of Fish and Wildlife.

"We are delighted that we did not find any sick foxes from distemper during this survey," said Clifford, who works with CDFW's Wildlife Investigations Lab. "We plan to return this spring after the pupping season to examine this year's pups, as weaning pups are especially vulnerable to distemper."

The outbreak of the fatal disease was noted in the second half of 2011 on the site of the Genesis solar project in Riverside County. The disease, which is incurable and often fatal, had not been documented in desert kit foxes before 2011. The source of the outbreak isn't yet known, though dogs at the nearby Wileys Well Road roadside rest area have been mentioned as a potential source, and we reported on another possibility here two years ago.

Desert kit foxes, Vulpes macrotis arsipus, are small predators that live in burrows in the open desert. Their preferred food in much of the California desert seems to be the Merriam's kangaroo rat, but they'll eat just about anything that they can catch, ranging from jackrabbits to insects. They can survive for years without drinking liquid water: they get their moisture from the animals they eat, and conserve it by staying underground during the day and venturing out to hunt at night.

Wildlife Investigations Lab staff trapped and tested 70 foxes over a two-week period, drawing blood samples and taking samples of mucus and saliva to test for shed viruses. (The disease is generally spread through contact with bodily fluids.)

None of the foxes trapped and sampled had distemper, a welcome bit of news for fans of the housecat-sized desert predator. A few of the foxes were fitted with radio transmitters so that their whereabouts could be tracked over the next few months. That data will help provide greater insight into how the foxes travel -- and how the deadly disease might spread, if it's still present in the desert fox population.

Though some animals, dogs included, can linger for weeks and even months with untreated distemper infections, the disease seemed to progress quite rapidly in the desert kit foxes near the Genesis solar project. That raises the possibility that the outbreak may have "burned itself out," killing off the core group of infected foxes too soon for them to spread infection to other groups. More study may reveal whether that's the case.

Desert kit foxes aren't the only rare California fox species susceptible to distemper. As we reported in November, Channel Island foxes are also vulnerable to the viral infection, with Catalina's population nearly wiped out 15 years ago.

In May of last year the Center for Biological Diversity petitioned the California Fish and Game Commission to have the desert kit fox listed as Threatened on California's Endangered Species List, citing the distemper outbreak as well as long-term threats to the fox's desert habitat.

That petition was declined due to gaps in available data on the foxes' numbers. But at least it looks like distemper might not lower those numbers dramatically before we can find out what they are.