NATURAL VIEW: Feeding wild birds has consequences

Bird watching and feeding are hugely popular pastimes. In the U.S., more than 60 million people put out seed, suet (fat), or fruit for local songbirds. We can now see the impacts of widespread feeding on the birds.

Audubon winter bird counts confirm that more birds now stick around for snowy winters instead of going south. Birds are very sensitive to having a plentiful food supply. In the mountains, tiny chickadees show up at my feeder in midwinter, fluffed out against the cold, but otherwise healthy and happy. Birds have effective anti-cold mechanisms, but they need lots of food to fuel their energetic metabolisms. Backyard bird feeding in winter helps the birds survive until spring.

Most feeders are designed to hold seeds, so they attract seed-eating birds like finches, goldfinches, doves, and sparrows. These birds have short, conical beaks to take the hulls off seeds quickly and efficiently. Some hawks and owls also benefit from backyard feeders, but not by eating bird seed.

Cooper’s Hawks eat almost exclusively birds caught on the wing. In the wild, these mid-sized brown and white hawks hunt and nest in oak woodlands, and like other woodland hawks, their wings are rounded and fairly short. This enables them to make tight maneuvers between trees as they chase down their prey.

Following their food source, the hawks have discovered that backyard bird feeders provide reliable concentrations of small songbirds. People with feeders see the hawks regularly. Some have abandoned the wild altogether and even nest in our neighborhoods. Not surprisingly, the number of Cooper’s Hawks is increasing. Following raccoons, opossums, coyotes, and bobcats, they are adapting to our urbanized neighborhoods.

The move is not without peril. In our gardens hawks have to deal with other formerly wild critters, plus house cats, thoughtless children (some with BB guns), tree trimmers, exotic tree squirrels, and mobs of nest-raiding crows. But the food is good, the supply is regular, and Cooper’s Hawks are pretty scrappy.

Not all raptors are faring as well. According to Scott Thomas, conservation director of Sea and Sage chapter of the Audubon Society, population numbers of once-common raptors like Barn Owls, Red-Tailed Hawks and Red-Shouldered Hawks are falling. These birds depend for food on small rodents plucked from flat grassy areas — primarily gophers, field mice, and ground squirrels. Red-tailed hawks are hunters of open areas, and we see them, long wings outstretched, wheeling high in the air over grasslands and gentle slopes. When they perch, they turn their brilliant white breasts toward the sun as if staking out a territory. They were among a few native species that thrived on the short-grass meadows created by cattle grazing. When grazing ended the bulldozers followed. Our remaining wildlands are mostly steep canyons and ridges — scenic land that also is difficult and expensive to develop. Flat land is harder to preserve. As a result, rodent-rich grasslands such as the bottom of Aliso Canyon are increasingly rare.

Orange County has been in a drought since 2000, and its remaining wildlands increasingly ravaged by fire. Any species, like the Cooper’s Hawk, that is able to adapt to our neighborhoods and make a piecemeal living will do so.

What about the others? There are already toad houses, bat boxes, butterfly feeders, squirrel feeders and anti-squirrel bird feeders. Maybe it’s time for backyard mouse feeders.

ELISABETH M. BROWN is a biologist and the president of Laguna Greenbelt Inc.