WERC Highlights -- June 2002

Sonoran Desert Tortoise Book: Three USGS researchers are among 32 scientists contributing to the first comprehensive summary of the ecology and conservation of the Sonoran and Sinaloan desert tortoises, “The Sonoran Desert Tortoise: Natural History, Biology and Conservation.” The 2002 book is part of a natural history series published jointly by the University of Arizona Press (www.uapress.arizona.edu) and the Arizona-Sonora Desert Museum. The ecology, physiology, and behavior of Mojave Desert tortoise populations (which are a federally protected threatened group) are quite different from those of their southern Sonoran Desert and tropical cousins, which have been studied much less. Differences in climate and habitat have shaped the evolution of three groups of desert tortoises as the deserts developed over the last ten million years. Todd Esque and Cecil Schwalbe of the Western Ecological Research Center are co-authors in chapters on the diet and fire ecology of the Sonoran Desert tortoise. Bruce Bury of the Forest and Range Ecosystem Science Center co-authored a chapter on the distribution, ecology, and conservation of the desert tortoise in Mexico. (Todd Esque, Las Vegas, NV, 702-914-2206-226; Cecil Schwalbe, Tucson, AZ, 520-621-5508; R. Bruce Bury, Corvallis, OR, 541-758-7788)

Large Fires Are Natural in California Chaparral: According to historical studies by USGS research ecologist Jon Keeley of the Western Ecological Research Center and C. J. Fotheringham at the University of California, Los Angeles, the natural fire regime of California shrublands was not one of frequent small fires that prevented large catastrophic crown fires. In a series of articles in Science, Conservation Biology, and Environmental Management these researchers have tested the paradigm championed by other researchers, that the natural fire regime on chaparral landscapes burned frequently enough to maintain the landscape in a mosaic of young age classes sufficient to act as barriers to large fires. Keeley and Fotheringham's research disputes the view that large catastrophic wildfires in California shrublands are the result of years of fire suppression, as seems to be the case on coniferous forests throughout the Western U.S. Their research also provides evidence that landscape-scale prescription burning is not an effective means of preventing large, destructive chaparral fires, which typically occur during Santa Ana wind conditions. The opposing views will be featured in a story in the Los Angeles Times science section, expected July 8. (Jon Keeley, Three Rivers, CA, 559-565-3170)

California Sea Otters Swim to the Surface: USGS scientists Jim Estes, Brian Hatfield, and Kevin Lafferty of the Western Ecological Research Center spoke with reporters about the recent decline of the threatened sea otter population. Media reporting on sea otter status include Associated Press, the San Francisco Chronicle, San Luis Obispo Tribune, Monterey Herald, Santa Cruz Sentinel, KSBY TV in Santa Barbara, and Channel 46 TV and KTX talk radio in Salinas. (Gloria Maender, Tucson, AZ, 520-670-5596)

New Wilderness Park Celebration: USGS biologist T'shaka Toure of the Western Ecological Rsearch Center will be on hand June 15 at the celebration of the Irvine Ranch Land Reserve, a newly reserved wilderness park in Orange County, California. At the USGS booth Toure will discuss USGS science support for habitat conservation planning in southern California counties. Monitoring efforts have documented thousands of amphibians, reptiles, small mammals, and invertebrates in Orange County. (T'Shaka Toure, Irvine, CA, 714-330-5042)

Safe Passage for Tortoises: USGS research wildlife biologist William Boarman of the Western Ecological Research Center will address the National Research Council's Committee on Ecological Impacts of Road Density meeting in Newport Beach, Calif., on June 19. Boarman will be discussing the results and implications of his 8-year study on the effectiveness of highway barrier fences and culverts at reducing desert tortoise deaths from vehicular traffic. Road mortality is a major source of death for threatened desert tortoise populations. The results of this multi-agency project indicate that the barrier fences used in the study were highly effective at keeping tortoises and other vertebrates off the roadway, and that tortoises used culverts to cross beneath the busy highway. (William Boarman, San Diego, CA, 858-637-6880)

California Sea Otter Status: Scientists tallied fewer sea otters this May for a second consecutive year. The number of otters counted in the recently completed spring survey was 1 percent below last year's count, from 2,161 otters in 2001 to 2,139 in 2002. Spring 2001 had also indicated a decrease, by 6.7 percent. Since 1995, increasing numbers of dead otters have washed ashore, 183 in 2001. So far this year scientists have already documented 92 dead otters. From these carcasses, they note that young and prime age adults are dying at elevated rates, a loss that hinders the threatened population's recovery. USGS scientists at the Western Ecological Research Center with the California Department of Fish and Game, Monterey Bay Aquarium, U.S. Fish and Wildlife Service and experienced volunteers surveyed about 375 miles of California coast, from Half Moon Bay south to Santa Barbara. The information gathered from these surveys is used by federal and state wildlife agencies in making decisions about the management of this sea mammal. (Jim Estes, Santa Cruz, CA, 831-459-2820; Brian Hatfield, San Simeon, CA, 805-927-3893) Official news release

Desert Frogs Clamor for Mates: USGS research ecologist Cecil Schwalbe of the Western Ecological Research Center hopes for enough rain this summer to fill temporary pools in the desert. If this happens, NPR can record deafening choruses of as many as 6 species of frogs that may gather at a single pond to call for mates. Schwalbe and other researchers are developing standard methods for monitoring amphibians that breed in temporary pools in southern Arizona and California. NPR will also get a chance to document Schwalbe and volunteers as they recapture bullfrogs marked earlier in the season to learn how far bullfrogs travel between pools. Earlier research found bullfrogs had traveled overland as far as 3.1 miles from where they were marked. Introduced bullfrogs prey on and compete with native desert frogs and toads. (Cecil Schwalbe, Tucson, AZ, 520-621-5508)