The Bullhead Queen: A Year on Pioneer Lake

The Nest Box War

The Nest Box War 103 A t the edge of our meadow rising up from Pioneer Lake, we have placed bluebird boxes, designed to attract the cheery sapphire birds to our yard. There is nothing lovelier on a summer day than to be in the presence of these beauties. “Bluebirds carry the sky on their backs,” Thoreau writes, and I think of this every time a male bluebird flies by. Bluebirds are cavity nesters, a group of birds whose populations have been declining for decades, for want of nest sites. Artificial boxes are intended to substitute for natural nest sites. In the past, cavity-nesting birds sought out woodpecker holes carved out of dead snags and, since the introduction of agriculture, holes in wooden fence posts, to serve as nest sites. However, with increasing human presence, dead trees are seldom allowed to stand; we lost one such tree, a cottonwood, a few years ago from the southeastern shore of Pioneer, a tree that had harbored a pair of nesting tree swallows, when the county took it down to tidy up a construction zone. And thin metal fence posts have replaced the old wooden ones in demarcating farm fields. The birds have taken to the boxes with enthusiasm. Although bluebirds were the original target for the help, other cavity nesters also make use of the planned community . This summer we have bluebirds in one box, a chickadee pair in another, and a pugnacious little house wren in a third. Over the years, we have frequently played landlord to tree swallows as well, which flash about the yard in their iridescent teal-blue plumage, all of these native songbirds, which we are happy to host. But another species, highly adaptable, has also benefited greatly from the boxes: the house sparrow. House sparrows are drab birds with a nonmelodic “cheep” for a song. Hailing from Europe, they have ensconced themselves in North American avifauna, breeding prolifically in urban concrete and suburban yards, producing five, six clutches of eggs a year, and aggressively outcompeting native birds for nest sites. Like European Americans, they are one of that continent ’s success stories in colonizing the New World. Bluebird enthusiasts have done meticulous research on box design, with an aim to encouraging bluebird residency and making it difficult for house sparrows to use them. But the sparrows are persistent and flexible, and the battle is easily lost, as we discovered one spring a few years back. We were given several bluebird boxes that had originally been destined for use in a state park, and my husband put them up immediately, since it was already May. Within an hour after completing the task, we were astonished and delighted to observe a bluebird pair investigating one of the boxes. The birds perched on the roof and the female peered inside, as if to gauge the suitability of the family room. The male flapped busily about. The female flew to the maple tree, perhaps to think it over. It must have made a favorable impression , because after a day or two, the box was clearly theirs, and they began to set up housekeeping. Within days, a second box was claimed by a pair of house sparrows. We were conversant with sparrow habits—how they will nest and renest, no matter how often one removes a nest—so we decided we would wait until there were eggs 104 The Nest Box War and then destroy the nest. We hoped, in a passive-aggressive way, to wear out the female. She could keep laying eggs— all that energy expended!—and we would keep destroying them, until she was sapped of her egg-laying ability. It seemed like a good plan. Unfortunately, we never removed the eggs. The boxes were constructed so that the front panel could only be removed with a Phillips screwdriver. A Phillips screw is of no consequence to the structure of the box, but because this box had been destined for the park, the screw had been used to thwart park visitors who might open the box and disturb eggs or nestlings. Sadly, the screws also served to thwart us from taking action against the house sparrows. Our Phillips screwdriver is tucked away in the toolbox in the basement. Whenever we considered the undesirable birds in the nest box, we seemed to be either on our way out the door and into the car, or on...