Pests, predators, and weeds

Figure 1: A ground squirrel. Photo/courtesy Devii Rao.

Pests

Control of pests begins by identifying the pest of concern. Some examples of pests that small acreage landowners may encounter are: flies, ground squirrels, rats, house mice, deer mice, pocket gophers, skunks, and opossums. Once you know what your species of concern is, you can take steps to minimize the pest’s access to the three things they need to survive: food, water, and habitat. Some examples include properly storing animal feed in pest resistant containers and removing brush piles that provide habitat for rodents. It is not always possible to prevent pests from accessing feed resources, such as when bales of hay are stacked out in the open and/or fed out to animals in the open. In cases like these, control measures may be needed. When planning and implementing control measures, it is important to learn about the life cycle of the pest and target control practices accordingly. For example, ground squirrels are less likely to seek out grain-based bait when green grass is abundant, so this control measure might not be effective in the spring.

Figure 2: These pictures show signs of what a rat infestation may look like (from left to right) - 1) oils deposited by rats on a cabinet, 2) burrow and scat from rats, 3) three Norwegian rats active in a barn. Photos/courtesy Jim Hartman.

Predators

Predation of livestock and poultry is a common issue faced by many small acreage landowners in California. Response to and prevention of predation will vary based on the resources that each landowner has available.

Common predator species

Common predators in California are coyotes, bobcats, black bears, mountain lions, and domesticated dogs. Many predator species are classified as game animals under CDFW code, including black bears. Coyotes are not classified as game animals. In addition, most bird species are protected under the federal Migratory Bird Treaty Act and the United States Fish and Wildlife Service (USFWS) manages most bird cases, except wild turkeys. Lethal control of these species is regulated and, in many cases, not allowed. You can read the Fish and Game Code for Birds and Mammals here.

Figure 3: Common predators in California; photos taken from trail cameras. Photos/courtesy Dan Macon (#1-3), Carolyn Whitesell (#4).

If you are experiencing predator issues, it can be helpful to install a wildlife trail camera to document visits and identify predator species. You can also visit California Department of Fish and Wildlife (CDFW) Human-Wildlife Conflict page to access technical assistance and learn more about the species-specific laws and regulations. To report a wildlife incident, you can use the CDFW Wildlife Incident Reporting system.

Gray wolves

Gray wolves are an apex predator that have returned to California. Wolves are currently primarily found in the north-east part of the state; however a wolf pack was recently identified in Tulare County. Wolves first returned in 2011 when members of Oregon’s pack dispersed into Northern California. The first pack in California was identified in 2015 and as of 2024 there are seven packs.

Currently wolves are listed as endangered in California under both state and federal regulations. Harassment or take of wolves is prohibited by law. For more information, visit the CDFW grey wolf page or check out this UC ANR Northern California Wolf Update Factsheet from 2021 (some of this information may be outdated).

Predator prevention methods

The UC ANR publication Livestock Protection Tools for California Ranchers provides an in-depth look at common preventative methods to keep your livestock safe against predators in California. Options include:

• Livestock guardian animals (i.e. dogs, donkeys, or llamas)
• Night penning
• Electric fence
• Fladry or Turbo-fladry (cloth or plastic flags attached to a rope or wire that can deter wolves)
• Frightening devices (motion sensor lights, etc.)
• Carcass removal (of dead livestock or dead wildlife)

While all of these tools can be effective on their own, using multiple tools in combination can help further reduce predator-livestock interactions.

Key: ♦ = highly effective; ◊ = moderately effective; ? = varying effectiveness; NA = no available evidence on effectiveness

Table 1: Livestock protection tool selection guide for predators of concern. Table adapted from UC ANR 2018 publication Livestock Protection Tools for California Ranchers.

Weeds

The foundation of a good weed management plan is preventing weed species from reproducing or setting seed. Many weed species are prolific seed producers with more than 100 seeds per flower; this is one characteristic that makes weeds so persistent on the landscape. Weed seeds can be dispersed via wind, water, birds, or even livestock animals (in their manure, or stuck in their hair/wool) For good weed control, the first step is to correctly identify the weed species, next consider available control options and find a solution that is the best fit for you. Control options include hand pulling or other manual removal such as a hoe, herbicide application, mowing, and grazing.

Figure 4: A sheep overrun by yellow starthistle, a common weed species found in California. Photo/courtesy Dan Macon.