Presumed Extinct: 20 k-rats

LOST SPECIES OF THE BAY AREA

Presumed Extinct: Berkeley kangaroo rat

As with the presumed extinct ivory-billed woodpecker reported in Arkansas in 2004, there is always the chance that a long-lost plant or animal will be rediscovered, thanks to persistent searching and luck. That’s true even in a busy metropolitan area like the San Francisco Bay Area. In May 2005, botanist Michael Park stumbled upon a population of Mount Diablo buckwheat (Eriogonum truncatum) on the slopes of Mount Diablo. The buckwheat was a  species long thought extinct, last seen in 1936 by UC Berkeley botany graduate student (and later Save Mount Diablo cofounder) Mary Bowerman. 

Spurred by the rediscovery of the buckwheat, it bears asking today which plants and animals endemic to – but presumed extinct in – the San Francisco Bay Area scientists continue to search for in the hope they may still be hanging on by a thread, waiting to be found and protected.

Berkeley kangaroo rat (Dipodomys heermanni berkeleyensis)

Illustration by Devin Cecil-Wishing

It was a neighborhood cat, not a biologist, that first collected a Berkeley kangaroo rat (Dipodomys heermanni berkeleyensis) in 1918 atop Dwight Way Hill in Berkeley, or so the story goes. The specimen found its way to Joseph Grinnell, director of the Museum of Vertebrate Zoology in Berkeley, who later described the subspecies based on this and other k-rats from the Berkeley hills. K-rats were later reported in isolated pockets throughout the East Bay hills; the last confirmed one was collected at the Calaveras Reservoir in 1940. All told, 20 individual Berkeley k-rats have been collected and confirmed. But there’s only so much that can be gleaned from museum specimens. About its preferred habitat, we know only what was scribbled in the field notes of the original collectors: bare ridgtops, rocky outcrops, thin soils, scattered chaparral, and small annual grasses. Although too little is known about the Berkeley k-rat to point fingers, there’s a consensus among biologists that urban development and domestic house cats likely took the hop out of the rats’ step.

Since the early 1980s, biologist Gary Beeman has been hot on the k-rat’s tail, plastering “WANTED” posters throughout Mount Diablo State Park seeking reports of the kangaroo rat’s existence, dead or alive. Over the years, reports of alleged k-rat sightings have trickled in, including several trapped and released in the late 1970s, one caught at the base of Mount Diablo and kept as a pet in the 1980s, and one “moused” by a Blackhawk house cat in the 1990s. As with any Bigfoot sighting, there were neither photos nor bodies to back these claims.

Since 2000, East Bay Regional Park District biologist Joe DiDonato has trapped eight k-rats during surveys near Ohlone Regional Wilderness. These Ohlone k-rats bear markings of both the Berkeley k-rat and its closest kin, the Tulare kangaroo rat (D. h. tularensis), and DiDonato is still looking for someone to perform the DNA analysis necessary to identify them definitively. “Until you get genetic data to disprove [berkeleyensis], you have to go on the current science, and the current science is the historic data Grinnell collected.” And based on Grinnell’s range maps, the small, isolated fringe colonies DiDonato has discovered are berkeleyensis.

Despite DiDonato’s discoveries, Beeman continues to search for indisputable proof of the Berkeley k-rat in the core of its original range, where its status as berkeleyensis can’t be questioned. With so many unconfirmed sightings well within the species’ range, Beeman is confident the species will turn up. Where? Alhambra Ridge, Blackhawk Ridge, Lime Ridge, Mount Diablo’s lower slopes, the hills above Crockett, and North Canyon Road in San Ramon are at the top of his list of likely locales.

Field Guide to the Lost Species of the Bay Area

SPECIES: Berkeley kangaroo rat (Dipodomys heermanni berkeleyensis)

LISTING STATUS: Species of special concern

FIRST/LAST RECORDED: 1918/1940

RANGE: Berkeley (Strawberry Canyon), Mt. Diablo, and the East Bay Hills (Orinda Park Pool, Siesta Valley, Calaveras Reservoir)

HABITAT: bare ridge tops, rocky outcrops, thin soils, scattered chaparral, and small annual grasses

FIELD NOTES: the Berkeley kangaroo rat closely resembles the Tulare kangaroo rat (D. h. tularensis), but can be distinguished by generally darker hairs, especially along the back, as well as darker broad stripes along the sides and tail, and smaller patches of lighter hairs on the ears and face; look for k-rat hunter Gary Beeman’s “Wanted!” posters in kiosks surrounding Mount Diablo State Park; if you want to tip off Beeman about a potential k-rat in your neighborhood, you can reach him at (925)284-2602

RESOURCES:

Draft Recovery Plan for Chaparral and Scrub Community Species East of San Francisco Bay, California, by the U.S. Fish and Wildlife Service


The account excerpted above was originally featured in the October/December 2007 issue of Bay Nature magazine.

Illustrations by Devin Cecil-Wishing.

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