CDFW Urges Natural Control Methods for Pesky Rodent Populations

Juvenile great horned owl
Juvenile great horned owl. CDFW photo by Phil Robertson.

Rats, mice and voles are commonly sighted around homes and businesses this time of year. The California Department of Fish and Wildlife (CDFW) encourages Californians to let nature control rodent populations by actively protecting their natural predators – owls, hawks, falcons, eagles and vultures – rather than using poisons to eliminate pests. Environmentally friendly tactics (such as providing tall trees that raptors favor) will encourage these birds of prey to hang around your yard and remove rodents for you.

Most raptors use the same nest for many years and some even pass from one generation to the next. Bald eagles are known to have used the same nest as long as 35 years. That makes them an excellent long-term control for rodent populations in the immediate area.

During breeding season, a family of five owls can eat as many as 3,000 rodents! You can encourage them by hanging a nest box on your property, but please don’t do that if you or any of your neighbors are using anticoagulant rodenticides. Remember that poisoned rodents can poison the predators, scavengers and pets that eat them!

Even though the state Department of Pesticide Regulation (DPR) and U.S. Environmental Protection Agency (EPA) have restricted public access to the most dangerous rodenticides, all rodenticides – including the types still available to consumers – are poisons that can kill wildlife, pets and children.

More wildlife could be saved if people would use sanitation, removal and exclusion to keep rodents out of homes and reduce their numbers. Like most animals, rodents will congregate and multiply where food is available and they feel safe. The easiest way to discourage them is to remove or modify anything that could make them comfortable. Sanitation is the first step to controlling rodents. For example:

  •  Keep your home and yard neat and clean. Don’t give rats places to hide.
  • Remove objects and plants that rodents can hide under, such as wood piles, debris, construction waste, dense vegetation and ground-covering vines like ivy.
  • Pick up fruit that has fallen from trees as soon as possible.
  • Secure your garbage in a tightly sealed can.
  • Seal water leaks and remove standing water that can attract unwelcome animals, breed mosquitoes and waste water.

To remove unwelcome rodents, set traps in secluded areas where they’ve been seen or are likely to travel: close to walls, behind objects, in dark corners, on ledges, shelves, fences, pipes and garage rafters. In areas where children, pets or birds might go, put the trap inside a box or use some kind of barrier for their safety. Check traps daily and wear disposable gloves when removing rodents from traps. Place them in a sealed plastic bag then into your garbage bin for weekly collection. Wash your hands after handling traps or rodents, even when using gloves.

Once you’ve removed mice and rats from inside the building, seal the entries they used to get in: openings where cables, wires and pipes enter buildings, and cracks or holes in the foundation, walls and roofs. Rodents can squeeze into holes as narrow as ½ inch diameter! Use hardware mesh and concrete, plaster or metal whenever possible. At the very least, stuff stainless steel or copper pot scrubbers, or Stuf-fit copper mesh wool into the spaces. All of these are sold online and at hardware and dollar stores.

If you feel you must use “rat poison,” please carefully follow the label directions for all rodenticides. Only use them in small treatment areas indoors or right against building walls in tamper-resistant bait stations, never out in open field or garden areas, where they’re most likely to reach wildlife and pets. Much more information and practical advice can be found at www.wildlife.ca.gov/living-with-wildlife/rodenticides.

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Media Contacts:
Stella McMillin, CDFW Wildlife Investigations Lab, (916) 358-2954             
Dana Michaels, CDFW Communications, (916) 322-2420