UC Davis Study Measures Costs of Growing Wolf Population

NORTHEAST CA — A team of researchers at the University of California, Davis, is using a network of motion-activated cameras, GPS-collared cattle, and genetic analyses of wolf scat and cattle hair to measure the impact of northeastern California’s growing gray wolf population.

The study, led by Tina Saitone and Ken Tate, both professors and Cooperative Extension Specialists at UC Davis, compared cattle herds in areas with significant interactions between cattle and wolves during three summer grazing seasons to those where wolves were inactive. Genetic analysis of wolf scat collected in Plumas and Lassen Counties in 2022 and 2023 found that 72% of scat samples contained DNA from cattle. Dr. Tate said in an email that his team estimated that cattle made up at least 55% of the wolves’ diet. Although some could have come from wolves scavenging on cattle that died from other causes, Dr. Tate said that natural cattle deaths during the summer are low, implying that wolves were killing cattle for food.

The researchers also estimated economic losses resulting from interactions between wolves and cattle. They found that cows exposed to wolves, compared to those in areas where wolves were not active, were less likely to conceive calves, and calves gained less weight after birth. As a result, a single wolf in areas with “moderate” conflict between wolves and cattle caused nearly $70,000 in indirect economic losses in a single season. A wolf in areas with “severe” wolf-cattle conflict could produce about $163,000 in losses in the same period.

Dr. Tate said the team’s research findings indicate that “conflicts and costs will only increase with expanding wolf numbers and geographic extent.”