For the Birds Radio Program: Bird Houses
The end of winter takes weeks or even months in the Northland, but we can make the process at least seem a little shorter. Gardening magazines help us envision the warm loveliness of spring and summer, and cleaning out old bird houses and building new ones help us both envision and provide for the lovely creatures that will carry warmth in from the south.
Most cavity nesters that winter here excavate their own holes, which they use for winter shelter, too. Woodpeckers are designed to build cavities, as are nuthatches and chickadees. Chickadee beaks look tiny and weak, but pack a wallop. Chickadees each maintain their own personal roosting cavity, and when mice or other creatures steal one, the chickadee must start over.
Unfortunately, a couple of foreign invaders, the House Sparrow and European Starling, never ever build their own cavities—they aggressively steal cavities from other birds. Starlings are amazingly successful even against big birds like flickers and Red-headed Woodpeckers. Many people wonder how a relatively small bird can take on, and even kill, such large species, but it’s all in the mouth. The muscles in most bird mouths get their strongest action when shutting, making it easy for parrots and grosbeaks to crack open hard seeds and nuts. Anyone who’s ever been bitten by a bird knows how powerful these muscles are. Starling mouth muscles pull the mouth open. This insect eater feeds by sticking its sharp beak into the soil and forcing it open, exposing subterranean grubs and bugs. When a starling usurps a flicker’s home, the flicker doesn’t dare argue the matter or the starling will stab it, flicking its beak open to inflict the same fatal damage as a cop-killer bullet. House Sparrows are known to kill both adult and baby bluebirds and swallows to steal their homes.
So when we build bird boxes, we have a responsibility to discourage these pests. Carrol Henderson, head of the Minnesota DNR Non Game Wildlife Program, is author of a great book of plans and suggestions for bird houses titled Woodworking for Wildlife. He suggests keeping pests out of flicker boxes by building the box with a hinged top and stuffing it to the top with sawdust. Flickers are primary nest builders—it’s easy for them to scoop out the sawdust while starlings and House Sparrows don’t have a clue how to clear it away.
Make bluebird and Tree Swallow boxes with a 1 1/2-inch hole. Not even the skinniest starling can squeeze through. Unfortunately, sparrows can still get in. Most people with bluebird trails check boxes periodically to toss out sparrow nests and eggs. Sparrow eggs are easy to recognize—they’re mottled brown while bluebird eggs are soft blue and Tree Swallow eggs are snow white. House Sparrows and starlings aren’t protected by law. Some people believe sparrows and bluebirds should coexist peacefully, but as Carrol Henderson writes, “If House Sparrows are successful in catching a a female songbird in a nest box with its young, it will kill the whole family by pecking their skulls open.” I personally wouldn’t have the heart to kill a baby sparrow, but I don’t mind tossing out their eggs.
This is the ideal time of year to get started on those bird houses. One swallow may not a summer make, but a pair of them in a bird house will sure make your summer a pleasant one.