Overview of Study

Following a century of expatriation, gray wolves (Canis lupus) returned to California in 2011, and populations have rapidly grown. This has created a challenge facing ranchers, policy makers, and conservationists: restoring wolf populations – a Statewide policy – while fairly compensating ranchers for direct (i.e., livestock kills) and indirect (i.e., reduced livestock performance) costs of cohabitating with a regulatorily protected large carnivore. There are three wolf packs currently active in California (Lassen Pack, Lassen and Plumas Counties; Beckwourth Pack, Plumas and Sierra Counties; Whaleback Pack, Siskiyou County). Increased wolf presence has intensified livestock direct depredation and stress.

State legislators have established a pilot Wolf Conflict Program (WCP) with an initial $3 million allocation in the 2021/22 California State Budget to provide compensation to livestock producers for wolf depredation events and losses in productivity due to wolf presence. The WCP will be administered by the California Department of Fish and Wildlife (CDFW). Clear research needs have arisen as a stakeholder working group has attempted to make the WCP science-based, efficient, and transparent.

Research suggests predator interactions affect cattle health and welfare in many ways that generate substantial indirect costs associated with stress driven reductions in nutritional status, conception rates, birth weights, and weaning weights. There has been a series of calls in the existing animal science and behavior literature to translate these physiological outcomes into economic estimates of the indirect impacts of predator interactions with cattle. However, to date there has been no comprehensive economic assessment that translates wolf-driven physiological and behavioral changes in cattle into indirect costs. In order to fill this gap in research, we have been awarded extramural grant funding from the Rustici Rangeland and Cattle Endowment and the Western Sustainable Agriculture Research and Education grant.

Brief Project Description

Like much of the Western U.S., many cow-calf operations in California depend upon winter and summer range to meet their annual forage demands. The livestock studied for the purposes of this project move from lower-elevation (100 to 1,500 feet), private annual grassland winter ranges in June to higher-elevation (5,000 to 7,500 feet) public summer grazing allotments and private grazing leases returning to winter range in September. This research effort is focused on summer grazing areas where the wolf-affected herds have typically interacted with wolves. 

1. Quantify the influence of wolf presence on cattle performance and grazing behavior across herds of cattle grazing on rangelands;
   Cows from wolf-affected and control herds will be randomly selected for GPS collars beginning with turn out on summer allotments. GPS collars will record date, time, and spatial position at five-minute intervals, facilitating collection of tracking of grazing behavior metrics (e.g., time spent grazing, flight response). 
2. Evaluate the impact that wolf presence has on stress levels in wolf-affected and control herds (using hair cortisol sampling); and
   Analysis of hair cortisol concentrations (HCC) has gained acceptance as a non-invasive indicator of long-term stress in animals. Fear of predation stimulates cortisol production, suggesting that wolf presence is likely correlated with declines in cattle performance and indirect economic consequences.Hair samples will be collected from the tail switch with hair cut as close to the skin as possible and the 3 cm closest to the skin will be retained for analysis. Subsequent samples, taken each time cows are moved between summer and winter range, will be harvested from the same region; with total hair regrowth will be used for analysis.
3. Translate predator-related changes in performance, behavior, and stress into economic costs (indirect predator costs).

Follow the Progress of the Study ...

To facilitate outreach to interested parties, we will roll out blog posts that provide details about all the aspects of the project as they occur in the field (e.g., building cow GPS units, clipping tail hair, tracking cattle movements remotely, etc.). The first post (coming soon) will discuss the selection of GPS units that will be used to track cattle. As part of this blog series, we will also provide more information about the CDFW Wolf Livestock Compensation Grants.