BARN OWLS, NOT POISON, CURE FOR RIVERSIDE RODENTS.

Byline: Seth Shteir Local View

A burgeoning population and accompanying development have created urban sprawl in many parts of the country, and Southern California is no exception. The result is increased pressure on natural systems in the interface of urban and rural or undeveloped areas. One problem that occurs in many cities that border natural landscapes is secondary poisoning of predators from anticoagulant poison used to control rodents.

Many businesses along the Santa Clara River in Santa Clarita are using anticoagulant poison to control rodents. Although controlling rodents in inhabited areas is important, using anticoagulant poison is a serious environmental problem. The poison not only eliminates the target pest, but can also kill domestic dogs and cats, coyotes, foxes, ground squirrels, kangaroo rats, ground feeding birds, hawks and owls. Ironically, many of the predators affected by secondary poisoning do much to control rodents.

An unusually high numbers of dead birds of prey are turning up in the Santa Clarita area. The cause of death of these raptors has not been determined, but the high concentration of individuals and the fact that they appear to have died of internal bleeding suggest secondary poisoning.

Anticoagulant poison that is used to control rodents causes internal bleeding and eventually death. The problem with this form of rodent control is that it takes several days for the rodent to consume enough poison to succumb. In the meantime, predators can eat the poisoned rodents and, in turn, ingest a lethal dose. Ground-feeding birds and squirrels can also eat the poison pellets if they spill out of the bait stations.

When I visited a mall along the Santa Clara River last month, I not only found poison bait traps placed outside a restaurant, but they were spaced along the foundation in 30-foot intervals. Despite the owner's concern that there were a higher-than-usual number of rodents in the area, I found open dumpsters and water leaks from air conditioners. Open dumpsters and free-standing water in the middle of a drought attracts rodents and other unwanted wildlife. In fact, a high concentration of poison bait stations will also draw rodents that interpret the stations as a food source.

First and foremost, there is a need to determine if a rodent problem actually exists in areas bordering the Santa Clara River. Second, better housekeeping might help alleviate the problem. If the problem persists, there are effective, ecologically sensitive ways of controlling rodents. One possibility is the installation of barn owl houses along the river floodplain. Barn owls have been used successfully to control rodents in California's Central Valley, Florida and some Pacific Rim islands. They are easy to attract, reproduce rapidly, can live in semiurban areas and are voracious predators. In fact, a family of five nesting barn owls can consume 3,000 rodents in a breeding season.

Barn owls often colonize new houses quickly. Tom Hoffman, a California wine grower and barn owl advocate, had barn owl families breed in nine of 12 installed houses in a matter of months. And the houses are surprisingly affordable. One type of no-frills barn-owl house sells for $39. A popular Web site recommends four to six houses per 50 acres. The maintenance of these houses is minimal. They only need to be cleaned and monitored several times a year. Tall cottonwoods that line the floodplain could serve as possible locations for the houses. Best of all, the houses would be in a strategic spot to eliminate rodents where they live and breed.

The city of Santa Clarita could begin a barn-owl pilot project by creating a study area with a two-mile radius ban on anticoagulant poison. The project area could be monitored, and it could be determined whether this solution would be feasible for other areas. If barn owls proved effective, the city and businesses could gradually phase out less desirable forms of rodent control, such as anticoagulant poison.

Using barn owls to control rodents is cost-effective and it works. The city of Santa Clarita has the unique opportunity to be on the forefront of an environmentally friendly, sustainable solution to rodent control. Perhaps most important, the birds of prey we enjoy watching and that serve as nature's rodent control would continue to live along the Santa Clara River.