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Marin IJ Articles

Encourage owls to keep your rodent problems in check

  • Nanette Londeree
  • Got problems with rats, mice or gophers? Interested in environmentally friendly methods to help reduce these pests? It’s easy — support your local owls and encourage them to hang around. These ethereal birds of the night that you’re more likely to hear than see, can be a boost to an overall approach at controlling unwanted rodents.

    With their large heads and forward-facing eyes, owls are easily recognizable. Exceptional vision coupled with acute hearing and the ability to fly silently, these raptors have feet equipped with piercing talons and hooked beaks for tearing flesh that make them formidable and efficient predators. According to the Marin-based Hungry Owl Project (HOP), a partnership with WildCare in San Rafael, a family of barn owls can consume 3,000 rodents in a four month breeding cycle and can often breed twice a year in Marin. That’s a lot of natural pest control.

    Owls common in Marin are the barn owl, the great horned owl and the western screech owl. The medium-sized barn owl has a pale heart-shaped face, white underbody and long legs. Their soft plumage helps muffle the sound of their feathers when flying, ensuring a silent approach when honing-in on their quarry. Their rather eerie vocalizations include screeching, hissing and sometimes a bloodcurdling scream.

    The great horned owl gets its name from the tufts of feathers on the head. This large, powerful bird is mostly nocturnal, usually beginning to hunt at dusk, seeking out a wide array of prey, some even larger than itself. In addition to rodents, it will consume rabbits, house cats, other small birds and skunks (it doesn’t have much of a sense of smell). Their call is a deep, stuttering series of four to five hoots.

    Small and fluffy, the western screech owl’s plumage serves as an effective camouflage when resting in a tree. The strictly nocturnal hunter starts to forage about 45 minutes after sundown and return to roosts 30 minutes before sunrise. Surprisingly, screech owls don’t screech at all; they have a soft, descending hoot similar to that of the great horned owl.

    Major risks to the owl population are poison baits that kill unwanted rodents (primarily rats and mice). They contain anticoagulants that can purportedly kill a rodent “after a single feeding,” though it may actually take four to seven days for the rodent to die. During that time, the rodent can consume more bait, increasing the level of toxin in their bodies that subsequently gets ingested by any predator that eats the tainted animal.

    In 2010 WildCare began a program to evaluate the impact of rodenticides on the animals brought into their care facility. Alarmingly, the most recent data available (2013 to 2014) indicated that 86 percent of all their patients tested positive for rodenticide in the blood.

    In addition to rodenticides, loss of habitat is another threat to owls. Nest boxes can provide homes for barn owls and screech owls to nest and multiply.

    “Encourage barn owls for rodent control due to their enormous appetites and superb hunting skills,” says HOP executive director Alex Godbe. “If the surrounding habitat is adequate for the owls to hunt, they can be easily attracted to a location, even small properties, by installing a barn owl nesting box.”

    In more wooded locations, screech owls boxes are a good alternative. For more information on nest boxes, go to the HOP website at www.hungryowl.org.

    So, how can you help the owl population in your environment? Don’t use poisons and provide habitat for these amazing allies for rodent control.

    “Rodent poisons are having a devastating effect on our predator population,” Godbe says. “The poisons move up the food chain and all predators are at risk and particularly the owls.”

    For rodent control, HOP recommends using an integrated pest management approach that includes exclusion, prevention and humane trapping along with encouraging owls and other beneficial predators.