California Wolves Put Pressure on Cattle
Two new studies from the University of California, Davis, have revealed important insights into how gray wolves affect cattle operations in California. The research shows that wolves are feeding on cattle more often than other food sources and that their presence can place significant stress on livestock.
Researchers studied wolves from the Lassen and Harvey packs in northeastern California. By analyzing scat samples collected during the summers of 2022 and 2023, they discovered that cattle DNA was present in 72% of the samples. Cattle were the most common food source found, appearing in 86% of samples in 2022 and 55% in 2023.
The study was led by Tina Saitone from the UC Davis Agricultural and Resource Economics Department. According to the research team, cattle have become an important part of the wolves' diet in the region.
“Whether it's through scavenging or whether it's through depredation, it’s a huge component of the wolves’ diet,” said Tina. “Their conservation success is because of livestock producers in the state.”
California's gray wolves are listed as endangered at both the state and federal levels. After being absent for nearly a century, wolves returned to California in 2011. The state is now home to nine known wolf packs.
Researchers believe a shortage of natural prey may be influencing wolf feeding habits. Mule deer, the primary wild prey available to wolves in California, have declined significantly over the past several decades. Deer remains were found in only 45% of the wolf scat samples, making them less common than cattle.
A second study examined how wolves affect cattle behavior and health. Scientists measured cortisol, a hormone linked to long-term stress, in tail hair samples from cattle living in areas with and without wolves.
The results showed that cattle sharing landscapes with wolves had cortisol levels 58% higher than cattle in areas without wolves. Researchers said this indicates that the presence of predators can create ongoing stress, even when livestock are not directly attacked.
The research team also plans to investigate whether increased stress could reduce conception rates in breeding cattle. Such effects could impact ranch productivity and profitability over time.
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