Current Findings on Grazing Impacts California’S Special Status Species Benefit from Grazing

EXTENSION SERVICE NEWS from the University of California Cooperative Extension, University of California, Davis Current Findings on Grazing Impacts California’s special status species benefit from grazing by Sheila Barry, University of California Cooperative Extension Livestock and Natural Resources Advisor for Santa Clara County Periodically, the United States Fish need to sustain grazing regimes and precipitation and soil conditions and Wildlife Service (Service) reviews rancher stewardship for the successful allow the growth of dense vegetation and revises listed species information, conservation and recovery of special results in conditions unsuitable for including conducting five-year status species occurring on California’s kit fox. Cattle grazing is thought to reviews, as required under the rangelands. be to be the most reasonable and Endangered Species Act (ESA). These economical method for landscape- reviews include new research findings Grazing Benefits Wildlife scale management of kit fox habitat. and impacts of recovery efforts for In the five-year review in 2010 Although overgrazing was species of special concern. on the San Joaquin kit fox (Vulpes recognized as a threat to the The following is a summary of macrotis mutica), the Service stated California red-legged frog (Rana current reviews by the Service of that additional threats to kit fox draytonii); findings since the listing, listed species occurring on California habitat had been identified. These reported in the 2006 review of the rangelands. Interestingly, in every threats include changes to vegetation species, concluded that managed case where grazing was originally structure due to non-native species livestock grazing at low to moderate considered to be a threat to the and altered grazing regimes. Kit fox levels has a neutral or beneficial effect listed species, it has been found that are vulnerable to coyotes in dense on frog habitat. Managed livestock managed grazing may be beneficial. vegetation. grazing around ponds can maintain In addition, for several species, Optimal habitat for the kit fox is a mix of open water habitat and managed livestock grazing has been considered to have low vegetation emergent vegetation. determined to be essential to prevent structure, common patches of bare In some cases, without managed further loss or decline in the species ground and abundant prey. It has grazing, stock ponds would quickly fill These findings, as reported by the been demonstrated that a reduction with emergent vegetation resulting in Service, overwhelmingly point to the or cessation of grazing on sites where habitat loss. In some locations fencing, CPP © 18 CALIForniA CAttLEMAN June 2011 which had excluded livestock from “protected” and not subject to Bakersfield, have shown dramatic ponds, is being removed to improve development, but without appropriate declines in numbers following habitat for red-legged frogs. grazing regimes, the butterfly has consecutive wet years and dense Much like the California red-legged disappeared from historical areas vegetation growth. Annual grazing frog, the California tiger salamander within “protected” lands. studies in the Lokern Preserce area, (Ambystoma californiense) is thought The five-year review released in about 30 miles west of Bakersfield, to be compatible with managed 2010 of the San Bruno elfin butterfly from 1997 to 2005 have demonstrated livestock grazing by cattle, horses and (Callophrys mossii bayensis) and the benefits of livestock grazing in sheep. It has been recognized that mission blue butterfly (Icaricia reducing exotic grasses and increasing grazing can maintain a low vegetation icarioides missionensis), recognized blunt-nosed leopard lizard numbers. structure, which makes areas more that coastal scrub succession Decisions to severely restrict or suitable for California ground continues unchecked and without eliminate livestock grazing from squirrels whose burrows are essential a comprehensive grazing and/or conservation lands may negatively to the tiger salamanders. controlled burning program, habitat affect blunt-nosed leopard lizards. In 2004, the Service decided that for these two butterflies will continue Fire as an alternative vegetation the long-term effect of ranching is to slowly decline on San Bruno management tool has also been either neutral or beneficial, as long as Mountain. It has been documented studied in recent years. It was found burrowing rodents are not completely that in the absence of grazing and to be less effective than grazing at eradicated. fire, coastal prairie grassland habitats controlling annual vegetation because The Service noted that the are being lost to shrub and tree the positive effects lasted less than one California tiger salamander would encroachment. year. have been eliminated from many areas The 1987 Service recovery plan Although studies in the 1970s if stock ponds had not been built and included livestock grazing as a threat identified grazing as a threat to Fresno maintained for livestock production. to the survival of the mission blue kangaroo rats (Dipodomys nitratoides The Service’s data from 2003 showed butterfly, due to encouraging the exilis), recent studies highlighted that less vegetation on rangelands may growth of weedy annuals and other by the 2010 five-year reviews of the also facilitate the movement of tiger exotic plants in the grasslands and Service with giant kangaroo rats salamanders from upland areas to reducing the amount of chaparral. (Dipodomys ingens) suggest that breeding ponds. Current studies, as reported in the both overgrazing and complete In addition, in 2004, the Service review, have shown that managed lack of grazing are detrimental for published findings noting sustainable grazing may increase the density of populations of kangaroo rats. Sites grazing around natural ephemeral native plants that support butterfly which develop thatch from non-native pools, including vernal pools, may populations. grasses not only impede the activities also benefit the California tiger A stewardship grazing plan was of the kangaroo rats and but also salamander by extending the wet developed for San Bruno Mountain, competitively exclude the native forbs period so amphibian larvae can the northernmost part of the Santa that are the preferred food source for complete their life cycle. Cruz Mountains, in 2002. Due, in the kangaroo rats. Overgrazing has previously been part, to lack of funding, the plan has Early studies reported the negative identified as a threat to the bay not been implemented. The Service effects of overgrazing on habitat checkerspot butterfly (Euphydryas recognizes that preventing the quality through competition for food editha bayensis). Current scientific continued loss of habitat will require between cattle and the giant kangaroo findings from the Service released sustainable funding sources and/or rat and the potential collapse of in 2009, state that a lack of grazing manpower and/or the reintroduction burrows by livestock. Recently, or undergrazing is a more common of San Bruno elfin butterfly. long-term grazing studies included threat to the butterfly. Grazing reduces Although overgazing was previously in the 2010 Service’s five-year review, standing biomass of non-native indicated as a threat to the blunt- have reported declines in the number vegetation, which if uncontrolled, nosed leopard lizard (Gambelia sila), of kangaroo rats (including the giant crowd outs forbs, including those current findings as reported by the kangaroo rat) on ungrazed plots essential to the butterfly. Service in its 2010 five-year review relative to grazed plots during wet Since maintaining an appropriate suggest that the cessation of grazing is years. grazing regime is essential to the likely to be even more detrimental. The actual cause of decline in butterfly’s habitat, the Service has Long-term studies of blunt-nosed kangaroo rats during wet years is also recognized that protecting leopard lizard population trends on unknown, but a possible factor is habitat from development alone is the Elkhorn Plain and Pixley National dense grass growth, which inhibits not sufficient. For example, state Wildlife Refuge, located in the San foraging; increases the risk of and county parks are considered Joaquin Valley between Tulare and Continued on page 20 June 2011 CALIForniA CAttLEMAN 19 ‘CURRENT FINDINGS on GRAZING IMPActs’ from page 19 predation by providing cover for Chloropyron palmatum), an annual hunting animals; and increases plant belonging to the snapdragon ALAMEDA COUNTY CONSERVATION soil moisture which may lead to family, when the species was listed PARTNERSHIP© fatal respiratory problems, or the under the ESA. infestation of kangaroo rat seed caches In the 2009 five-year review on with toxic molds. Livestock grazing the plant, the Service recognized can control the dense growth of that cattle grazing may be beneficial non-native grasses that threaten giant and, in some cases, can have harmful kangaroo rats during wet years. effects. Grazing can enhance habitat The Service concluded in the species for the flower through the removal review that while overgrazing may of invasive non-native plants. But, disturb individual giant kangaroo rat unmanaged grazing can negatively- precincts, the cessation of grazing may impact habitat through physical Canyon, in Western San Joaquin lead to a significant decline in giant destruction, like soil compaction or County. When the site at Carnegie kangaroo rat numbers particularly wallowing

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