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Promoting cavities

Educated help boosts birds looking for nest sites

House hunting is entering its seasonal boom in the Inland Northwest, and savvy birding enthusiasts are working to improve the market.

As more of the region’s land is developed and dead trees are removed for safety or firewood, cavity-nesting birds such as chickadees and bluebirds have been left out in the cold.

Bluebirds are “secondary” cavity nesters that rely on woodpeckers and other primary cavity nesters to excavate and then abandon holes in trees.

“We can give all of these birds a boost by providing places for them to nest,” said Alan McCoy, a piano repair specialist who donates his craftsman talents to building nest boxes as a Spokane Audubon Society fundraiser.

“If people are going to go to the effort to build or buy a birdhouse, we want to encourage them to make boxes the right size, put them in the right places and maintain them.”

Otherwise the effort can do more harm than good to native birds, he said.

Spring officially arrived Friday, but many species have been surveying nesting sites for weeks.

While bluebirds started showing up two weeks ago, look for house wrens to arrive around the third week in April.

Some birds nest on the ground or in trees, barns and under bridges.

Other birds prefer tree cavities or other natural features, but will use man-made nest boxes when natural sites are scarce.

Owls are among the few birds that consider their nest a home. Most birds use nests only for rearing offspring, or sometimes for surviving a winter cold snap.

Building nest boxes, or simply cleaning boxes that already have been set out, can be fun family projects that set the stage for observing bird families through the spring.

The first step is learning what kinds of nest boxes are used by birds in a specific area.

Bluebirds doubtless need all the help they can get. But the woods in city neighborhoods generally are not in appropriate habitat.

Bluebirds prefer sunlit areas near open meadows. This habitat is abundant around the edges of Spokane and throughout much of North Idaho to fairly high elevations. But it’s not so common in town.

Less glamorous birds, such as nuthatches and violet-green swallows, might be more likely to take up housekeeping in a box, say, on the South Hill.

Wooded areas are more likely to harbor chickadees, woodpeckers or screech owls.

Although not as showy, the house wren is another secondary cavity nester worth inviting into a suburban yard.

The male house wren will build nests in several cavities and let his mate choose the one she likes best. The little male puts his heart into cramming sticks as long as 8 inches into the tiny nest box opening. He likes to leave a few inches of a stick protruding out the hole to discourage other nest-seeking birds.

The house wren is one of the most beneficial birds a gardener can have in his backyard, said Jim Acton, Spokane Audubon Society veteran birdwatcher.

“That little bird will inspect everything in the garden, including the stems, leaves, branches, ground cover and even the understructure of the roof in search of grubs, caterpillars and spiders.”

Similarly, people who install proper nest boxes under the eaves of their house may invite violet-green swallows that will patrol the skies to control flying insects.

Orchardists often install dozens of nest boxes for kestrels, which pay back the favor by providing rodent control.

But any nest box won’t do for these special birds. Bluebirds, woodpeckers and other cavity nesters have specific needs. The bigger the bird, the bigger the nest box should be. Placement also can make a difference. And size and design of the opening are important to keep out competitive exotic species such as starlings.

“The entrance hole size should be precise,” McCoy pointed out.

If you’re interested in luring house wrens, for instance, make an entrance hole as small as 1 inch in diameter to discourage most other birds except for nuthatches.

Research has shown that a difference of 1/16-inch in the diameter of a nest box hole can make a big difference in whether bluebirds or pillaging house sparrows fledge out of a box.

McCoy looks for donations of scrap wood, partly for value, but also because birds tend to prefer weathered or rough-cut wood.

An attractive yard also is a bonus to luring nesting birds.

A vast expanse of chemically treated lawn with immaculate barked flower beds is not as appealing to birds as a yard with a more natural character and variety.

Generations of birds are likely to return year after year if you provide the right housing and appropriate habitat.

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