In Washington and North America as a whole, the House Wren population has been on the rise since 1966, increasing an average of 8.3% per year in Washington and 1.6% per year in North America, based on Breeding Bird Survey data. In some areas in the 19th Century, there was a decline of House Wrens, which is blamed on the introduction of the House Sparrow because they compete for nesting cavities. Wrens will use a house that has an entry hole dimension of 1 1/8 inches, any larger and house sparrows and other less desirable birds will use them. They also seem to benefit from logging, using slash piles and small snags. They are fairly tolerant of human activity, which makes them well adapted to our increasingly developed landscape. This fragmentation increases the shrubby edge habitat that they prefer. House Wrens have benefited from the fragmentation of forests across the United States, including Washington. House Wrens currently occupy the broadest latitudinal range of any native songbird in the New World. Since many other birds also do this, the posture is by no means diagnostic of wrens. Many wrens hold their tails cocked up over their backs. Male House Wrens typically defend more than one cavity, and may fill all of the nest boxes in the territory with twiggy mock nests. This may protect them from predators that might abandon an area after finding most of the nests empty.

One theory to explain this, as well as the multiple nests, is that wrens strive to increase the number of empty nests in their territory. One odd practice of wrens is their tendency to puncture the eggs of other birds, both of their own and other species. Incubation is usually by the female alone, although both parents feed the young. The female then selects one nest and completes it. Usually the male begins a number of nests, which typically have coarse foundations upon which the actual nest cups may later be built. Most species lay eggs in enclosed areas, either in cavities or covered nests. They are usually solitary or in pairs and do not form flocks. Active foragers, they generally search for food low in the understory or on the ground, where they use their narrow bills to probe in crevices for insects and spiders. The wrens of northern North America are small, brown birds, which make up for their drab colors with their complex songs.

House wren