Sometimes the data just refuses to cooperate with the narrative and such was the case in a recently released and udderly damning study coming out of California last week.
A new University of California, Davis study, published in PLOS One, took a hard look at what California’s returning wolves are actually putting in their stomachs. The method was refreshingly straightforward and included collecting scat from the Lassen and Harvey packs in northeastern California over two summers (2022–2023). Researchers then ran some DNA metabarcoding, genotyped the wolves, and crunched the numbers in an attempt to figure out their favorite meal choices.
And for those of us that have been paying attention to what’s been happening in Colorado, it should come as no surprise to learn that cattle DNA turned up in 72% of the wolf scats. Mule deer, their supposed natural prey, showed up in about 45% of samples while small mammals clocked in at 51%.
The study revealed that seventeen out of 20 individual wolves identified had eaten cattle. By biomass (what actually sustains them) cattle made up roughly 55% of the diet on conservative calf-weight assumptions. Bump it to adult cows (which the wolves are also confirmed killing) and you’re looking at over 80% in some estimates.
Mule deer? A measly 12%.
As lead author Tina Saitone put it with admirable bluntness: the cattle industry in California is most definitely “supporting the conservation success of wolves.”
It’s not just direct predation either. Related UC Davis work measured cortisol in cattle tail hair and found that herds coexisting with wolves showed 58% higher stress hormones. Which, of course, translates to cattle herds gaining less weight, conceiving less reliably, and generally living in a cortisol-spiked environment. These are those types of quiet, compounding costs the state doesn’t fully reimburse while patting itself on the back for predator recovery.
In 2025 the Beyem Seyo pack in Sierra Valley killed or injured 92 cattle over roughly seven months. Direct livestock losses were estimated around $235,000 and Cali agencies spent more than $2 million on intervention, which included over 18,000 staff hours of hazing, monitoring, and non-lethal efforts. The combined estimated impact is believed to be at least $2.6 million worth of trouble from a single pack.
UC Davis
Why the Shift?
Here’s the part the performative conservation set hates to acknowledge: wolves are opportunists. California has spent decades presiding over declining mule deer herds in key areas. Add abundant cattle on grazing allotments in a human-shaped landscape, layer on full legal protection that largely prevents ranchers from defending their stock, and the result is predictable. Predators eat what’s easiest and most plentiful.
Gray wolves remain fully protected under both state and federal law in California and ranchers generally cannot use lethal control even to protect livestock or working dogs. The result is a system where predator recovery metrics look strong while the economic and ecological costs are pushed onto the people managing cattle on the same ground.
A North American meta-analysis pegged domestic livestock at around 8% of wolf diets in the studies where they appeared at all. The state of California is running somewhere between 8 and 9 times that rate, while attempting to cloak it in some kind of mysterious wolf behavior that looks a lot like basic supply and demand in a broken ecosystem.
Declaring wolf recovery a smashing success while the prey base is anemic and the ranching community foots the bill (literally and figuratively) is the kind of accounting that seems only to fly in certain coastal conference rooms. The fact remains that real landscapes run on forage, population dynamics, and working people trying to make a living without becoming an involuntary wildlife feeding program.
All said, this research doesn’t require hating on wolves nor should it demand their removal, at least not at this point. It does, however, require refusing to lie about what’s happening. Healthy predator-prey systems need actual prey and when wild ungulate numbers crater, the costs don’t disappear — they migrate to the balance sheets of the people still stewarding the land.
And for those of us who prefer functional ecosystems over comforting fictions, perhaps the scat is worth paying attention to.
