More problems with using poison to control rodents. There’s the risk of secondary poisoning of wildlife and pets as suggested in the DFG news release below. There is also the risk of direct poisoning of wildlife and pets around your house and yard when you use these poisons.
Rats and mice sometimes carry pieces of poison bait from supposedly safe bait stations used around your home and leave these pieces of poison bait lying in unprotected places in your yard or house where pets (or children!), or other wild creatures can find them. If you must control rodents, I recommend using traps and NOT poisons. /Gary
DFG News, Aug. 17, 2010:
Wildlife Experts Issue Warning about Controlling Rodent Pests with Poison
State and county officials remind Californians to use caution when using poison baits (rodenticides) to control rodent pests. Careless use of these chemicals has injured and killed wildlife and pets throughout the state.
The California Department of Fish and Game (DFG) and County of El Dorado Environmental Management Vector Control have issued the warning in response to a recent increase in the use of such baits, as residents are responding to a rodent population explosion. In El Dorado County and other parts of the state, unusually high numbers of voles are creating problems for homeowners. Voles are small, outdoor rodents that build and use grass “tunnels.” They are similar in appearance to house mice, with short tails and smaller ears.
Residents should be aware of the dangers that some rodenticides pose to wildlife and pets, particularly through secondary poisoning. Secondary poisoning occurs when scavenging species eat dead or dying rodents that have been killed by rodenticides. Owls, hawks, other scavenging birds and predators such as raccoons, fox, skunk and coyote are at risk. Pets will also eat dead or dying rodents and unprotected bait. Deer may be attracted to the pellet forms of rodenticides.
Over-the-counter rodenticides – including many commonly known brands – that contain the active ingredients brodifacoum, bromadiolone or difethialone can only be legally used to control rats and house mice in and around structures. It is not legal to use these products in open areas such as pastures or fields.
Bait products that contain the ingredients chlorophacinone or diphacinone can be used legally to control outdoor rodent pests such as voles, ground squirrels and gophers. These compounds require multiple feedings to kill rodent pests, so they pose a lower secondary poisoning risk compared to rodenticides used to control mice and rats within homes, barns or other structures.
It is important to read rodenticide product labels carefully and to strictly follow all use directions. Rodenticides should only be used in small treatment areas close to structures. Be sure to check these areas daily for dead rodents. Collect the carcasses as soon as possible, place in plastic bags and dispose in garbage cans with tight lids that other animals can’t open. Always wear protective gloves when handling any dead animal.
Since 1994, DFG’s Pesticide Investigations Unit has confirmed at least
136 cases of wildlife poisoning from anticoagulant rodenticides. Brodifacoum was the poison most frequently detected. Animals impacted include coyote, gray fox, San Joaquin kit fox, raccoon, fox squirrel, bobcat, red fox, mountain lion, black bear, Hermann’s kangaroo rat, golden eagle, Canada goose, great-horned owl, barn owl, red-shouldered hawk, red-tailed hawk, Cooper’s hawk, turkey vulture and wild turkey.
“Since animals typically retreat to their dens, burrows or other hiding places in the final stages of anticoagulant poisoning, the number of non-target wildlife killed by this compound may be much greater than we know,” said DFG Environmental Scientist Stella McMillin. “For the research we did, most of the birds and mammals exposed to brodifacoum were collected in areas adjacent to urban development around the state.”
*** More information on protecting wildlife and pets from rodenticide baits is on the DFG website at http://www.dfg.ca.gov/education/rodenticide/.
*** Protect your wild neighbors and pets from accidental poisoning. Use pesticides very carefully and follow all label directions, or choose organic or mechanical methods to control pests. More information on voles and alternatives to poison can be found on the University of California, Davis Integrated Pest Management Program website at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7439.html.