How birds safely forage at feeders

Some people who feed birds fear that feeding stations might simply be meat markets for predators. Not true.

"The bird feeding environment does not appear to expose birds to a higher risk of predation than is encountered in the absence of feeders," according to a study done at the Cornell Lab of Ornithology.

This discussion with myself began several months ago when I watched a song sparrow align itself within the shadow of a 1-inch pipe while feeding in our yard.

The pipe, pounded in place, is topped with arms from which hang four tube feeders. The sparrow was feeding on scattered sunflower seeds. This part of the yard has both sun and shade. Foraging opportunity was the same throughout.

The bird consistently chose shade. If it had to move to grab a seed it quickly returned to shade, even that skinny inch of shadow. The bird knew: It was more difficult to be seen in the shade.

Conditions at feeding stations, sun and shadow, have been the subject of many ornithological research efforts.

For instance, brown-headed cowbirds in the sun took longer to become aware of and flee from ground predators when compared when birds in the shade, a study found.

Birds may generally avoid foraging in direct sunlight to minimize their risk of predation. Research showed that house finches avoided feeding in sunlight, where they would have to spend more time watching for danger, less time eating.

The study also found that sunlight can cause visual glare that might reduce a bird's ability to monitor the environment. In some cases raptors attacked with the sun at their backs, like human combat.

Sun has warming benefits, a factor in winter. There is benefit from offering feeding in a situation offering both sun and shade.

The Cornell study counted 26 species of feeder-related predator. Eighty percent of the predation was attributed to sharp-shinned and Cooper's hawks and domestic cats.

The researchers found feeder birds to relatively be most vulnerable, and flocking birds more so than solitary. Hawks were attracted to feeders, cats were not. In another study, cats were found to pose most danger to solitary birds.

If the predator is an opportunist, like a hawk, birds should feed in a flock, the larger the better, a study showed.

Chickadees pull seeds from a feeder and fly away with the seed to open it elsewhere. Chickadees at our feeders do that all the time.

"When the cost of carrying is low and the benefit gained is high, the chickadees [will] elect to carry items to cover," according to research published in the journal Animal Behavior.

Protective cover minimizes the time the bird is exposed to predators. Eating at the source of the food can increase exposure, the research team wrote.

The goal is gaining more energy from feeding than the energy it takes to feed.

We've built brush piles near feeders to offer cover. Ground-feeding birds most often are the ones scurrying for these hiding places.

Ideally, feeder setups include nearby trees or shrubs, a brush pile, some shade, some sun, protection from wind, clean feeders and black oil sunflower seeds (all the birds eat these). Or, whatever you can do.

Perhaps more important, place the feeder(s) where you can see them easily and often and fill them conveniently.

Everything considered, the birds really don't need us. We need them.

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com.