California Wolves' Main Food Source Isn't Wild

California's resurgent gray wolves are leaning heavily on an unintended food source: cows. A new study in PLOS One finds that cattle make up an estimated 55% of the wolves' diet in the state, compared to about 40% from wild prey such as deer, small mammals, and birds, per the San Francisco Chronicle. DNA analysis of scat from two Northern California packs showed cattle in 72% of samples; small mammals appeared in 51% and mule deer in 45%. Researchers also detected bison, chickens, and pigs, likely from farm waste or garbage. The results highlight a tension at the core of the predator's comeback: "Their conservation success is because of livestock producers in the state," study co-author and UC Davis economist Tina Saitone tells the Los Angeles Times.

California now has roughly 12 packs totaling 50 to 100 wolves, mostly in the north. While wolf kills remain a small slice of overall cattle deaths, losses can be costly and, ranchers say, stressful for herds. The shift also "risks altering generational feeding patterns" and brings wolves closer to communities, "increasing the potential for conflict," according to the California Department of Fish and Wildlife. The study's authors argue the findings justify giving ranchers more authority to deter or even kill problem wolves, despite state and federal protections. Conservation groups counter that better nonlethal protections for livestock and boosting deer and elk populations are the way forward.