Raptor perches set to control squirrel invaders (CA)

[Donna]

 The rampaging ground squirrel population in Contra Costa County is truly for the birds, according to agricultural officials.

The county recently put up 20 raptor perches on land in Concord and Walnut Creek where gangs of the rascally rodents have been devouring fruit trees, digging up lawns, invading homes and taking over schools.

The man-made perches are there to attract hawks, falcons and eagles in the hope that they will eat the furry mischief makers and halt their incursions into suburbia.

It is the first time a county government has attempted to control a wild rodent population by luring in predatory birds.

"For years we have received complaints from homeowners that these ground squirrels have been coming onto their property," said Cathleen Roybal, the chief deputy agricultural commissioner for the Contra Costa County Department of Agriculture. "They dig burrow systems under lawns and foundations and they can undermine people's houses. They help themselves to backyard fruit, community gardens and they carry fleas, which can carry diseases."
School invasion

Roybal said the squirrels have recently invaded local schools, where they've stolen children's lunches, munched on wiring and set off alarms.

During a recent trip to Lime Ridge, an open space area next to several housing subdivisions, Roybal pointed out the giant holes the squirrels dug to enter and exit their labyrinthine underground burrows. On a sunny day, she said, Lime Ridge in both Concord and Walnut Creek and Shell Ridge Open Space in Walnut Creek is alive with scurrying rodents.

The perches, built by Wild Wing Co., in Cotati, each stand 15- to 16-feet tall and have wooden platforms oriented so that the raptors can face north, away from the sun. They were strategically placed next to large burrows where colonies of the problem squirrels hang out.

The project, which was paid for with a $4,000 grant from the California Department of Fish and Game, is a unique solution to a common problem.
Highly adaptable

The California ground squirrel, known scientifically as Spermophilus beecheyi, ranges throughout California and particularly likes open rangeland. The cute, bushy-tailed squirrels grow up to a foot long and quickly adapt to humans, especially in areas where picnickers leave them food.

Despite their cuddly look, they have long been regarded as pests. They feed on ornamental plants, trees and will eagerly devour vegetables. They gnaw on the bark of trees, shrubs, vines and burrow around roots.

Ground squirrels are also apt to gnaw on sprinkler heads and irrigation lines. They have been known to harbor bubonic plague, which can be transmitted to humans by fleas.
Population explosion

Contra Costa County has always had a large squirrel population, but wildlife experts said the situation grew into a crisis in part because of development. The clearing of land for housing forced predators, including raptors, to find other places to forage. As a result, open space next to these developments became overrun by ground squirrels.

Roybal said the county agriculture department stopped using pesticides to control the squirrels years ago because of city regulations, so she began researching natural ways to control the rodents.
Perches at key sites

The perches, which were put up in late October, seemed the perfect solution because the highest concentrations of squirrels are in areas devoid of the trees and snags that squirrel-eating raptors like to use.

"What we are doing is introducing man-made dead trees that the birds really covet," said John Schuster who, as the owner of Wild Wing, began building barn owl boxes and raptor perches 30 years ago for grape growers and farmers who needed to control rodents. "It gives them a safe place to hunt from and a secure and stable platform that predatory birds really like to work off of."

The plan is to monitor the perches for a year to determine whether they are being used. Wildlife biologists and volunteers have photographed American kestrels on the perches and found bird droppings and the remains of voles and gophers underneath, indicating owls and smaller raptors are using them.

So far, she said, the red-tailed hawks, peregrine falcons and golden eagles that agriculture officials would like to see have not been spotted and no squirrel remains have been found on or around the perches.

"It's too early to tell whether they will hunt ground squirrels, but there is no doubt the perches are helping the raptor population," Roybal said. "Squirrels are a pretty good size so you're going to need a big bird to take those. We don't know if it will work, but we thought it was worth a try."

[Carol P.]

"So far, she said, the red-tailed hawks, peregrine falcons and golden eagles that agriculture officials would like to see have not been spotted and no squirrel remains have been found on or around the perches."

What they need is a resident family of Red-tailed Hawks.  They just love squirrels.  Peregrines wouldn't be interested.