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People have long been fascinated by owls. Search for the term owl facts and you’ll find lists such as fun owl facts and awesome owl facts (because, well, owls are awesome). On some of these lists, you’ll learn that a Barn Owl can eat up to 1,000 mice each year. Many owl species are voracious eaters and feed mostly on rodents. But for owls today, capturing and eating their main food source could prove deadly. Many owls, other birds of prey such as hawks and eagles, and mammals such as foxes, bobcats, and domestic cats and dogs die each year by consuming rodents that have been poisoned by rodenticides. Recently, Oregon Department of Fish and Wildlife veterinarians issued a press release advising people to use alternative methods for controlling rodents. The Cascades Raptor Center here in Eugene has documented an increase in the number of poisoned birds they have seen and urges people to avoid using rodenticides (see
Anticoagulant rodenticides in the form of pellets, bars, or dust are widely used both indoors and out for pest control. When ingested, the chemicals result in widespread bleeding throughout the body and ultimately death. Because these poisons are slow acting, animals might continue to eat them for several days; as a result, the poisons can accumulate to levels several times the lethal dose. Poisoned mice, rats, and voles are lethargic and stumble around out in the open where they become easy prey. Birds and other animals that consume the poisoned rodents suffer similar fates. 
Due to the documented hazards of rodenticides to children, pets, and wildlife, the Environmental Protection Agency is working to limit purchases to first-generation chemicals, which are (slightly) less toxic. Many proposed reforms have been delayed by the companies that sell rodenticides, including the makers of d-Con rat poison. In California, regulations go into effect this summer (July 1, 2014) that will make it difficult for consumers to purchase second-generation anticoagulation rodenticides that contain the active ingredients Brodifacoum, Bromadiolone, Difenacoum, and Difethialone. (Second-generation rodenticides are more concentrated and more toxic than first-generation rodenticides and might work with a single ingestion.) But problems persist: Pest-control companies will still be allowed to use second-generation poisons, growers will use licensed operators to purchase large quantities of these chemicals, and the regulations can be evaded by purchasing the products online. In addition, some first-generation chemicals (Diphacinone), although less lethal to mammals, have been shown to be very toxic to birds.
Please do not use rodenticides. If you are dealing with an infestation and must use a pest-control company, find one that does not use poison. Nontoxic alternative products are available. See
The best solution for pest problems is prevention. Recommendations include the following:
  • Restrict access. Seal holes, especially around sinks and pipes, doors and windows, basements, attics, and access to crawlspaces.
  • Don’t leave food and water exposed (indoors or out.) Put away pet food and water at night. Repair leaky pipes. Store food in tightly sealed containers.
  • Seal trash and compost around structures. 
  • Remove invasive ivy—it shelters rodents, attracts rodent food, and acts as climbing ladders. Consider planting natives to provide habitat for native species rather than pests.
  • Clean the ground around bird feeders.
  • Keep outdoor cooking areas clean.
  • Keep firewood off the ground and away from structures with potential rodent problems.
  • If you want awesome pest control, encourage barn owls to nest and stay in your area by installing a nesting box. Please note that you should live in a suitable location and have neighbors who do not put out poison.