I wish to report a murder. Several actually.
This spring I had the good fortune to attract a pair of western bluebirds to one of the many bird boxes on my property. The pair worked hard to build the nest. Flashes of brilliant blue accented the yard as they went about their work. After hatching, the pair worked tirelessly heading out to the neighbor’s pastures searching for caterpillars and other crawling prey to bring home.
Then disaster. As I returned to the house from the garden one afternoon, I happened to pass by the nest box just as a male house sparrow left the box. Not good. I hadn’t seen a house sparrow in the yard all spring. The bluebirds called softly in protest. I waited two days before checking the box in hopes that all was well. But no. The adults had departed. Inside the box I found three dead chicks. The house sparrow had dispatched the young and moved on.
I have a special dislike for house sparrows. I said I had several murders to report. Over the years I have, by chance, directly observed male house sparrows destroy both a clutch of tree swallow eggs and a brood of tree swallow young.
I am careful when I construct bird houses. For most I drill a 1-1/8-inch hole. This permits species such as house wrens, black-capped chickadees and oak titmice to enter, but not house sparrows. For violet-green swallows, I cut a flat oval 7/8-inch high and 2 inches wide. The body of a violet-green swallow is tiny but the wings are large.
This poses a dilemma for me. If I construct boxes with the dimensions listed above, I exclude other species I wish to encourage, including tree swallows and western bluebirds.
So, I take the chance. I place a few boxes with larger entrances on the property. I monitor these closely to make sure no house sparrow begins to build a nest. This however, does not prevent them from entering the nests of others.
My defense against house sparrows goes beyond nest boxes. I discourage them from my yard at all times of the year. I do not feed the birds during the spring and summer. No seed means fewer to no house sparrows. Further, I am careful what I feed birds in winter. I do not feed millet. While cheap, millet is a favored food of house sparrows. Unfortunately, millet is also favored by other species, including mourning doves and house finches. At the risk of being less welcoming to the latter, I feed only black oil sunflower seeds. House sparrows will eat sunflower seeds on occasion, but not often. I also avoid placing seed in elevated feeders. Feeders benefit house sparrows more than others. Gluttonous scrub jays also prefer the elevated convenience. I don’t need more scrub jays. Nyjer seed feeders, unlike trays, are rarely used by house sparrows.
Instead I spread the seed on the ground where it is appreciated by golden-crowned sparrows, towhees and others. This has the dual advantage of both avoiding the spread of disease and discouraging house sparrows. There is a downside. If there are cats about, they appreciate the convenience. You may end up feeding more cats than birds. Good luck.
Stewart Janes is a biology professor at Southern Oregon University. He can be reached at firstname.lastname@example.org.