The House Wren Nesting Preferences
The male House Wren starts building nest within the breeding territory even before he has a mate. The male wren builds nest in all the cavities it can find and destroys the eggs of birds of other species within its territory. The nests built by the male wren are often referred to as dummy nests since the female wren will choose only one nest among all the nests prepared by the male wren. The dummy nests built by the male wren is not a finished product though since the male wren makes use only of sticks and just partially covers the cavities. Male wrens prefer to make use of dry dead sticks as opposed to green ones.
When the female bird arrives the courtship begins and along with it comes the inspection of the available nesting sites. The female bird inspects all available nesting sites, even those that have not yet been filled with sticks by the male bird, and chooses the site it deems suitable as the final nest. Sometimes the two birds disagree on a nesting site or the material used by the male bird and so fights even while courting each other. At times when the female bird disapproves of the material used by the male bird it dismantles the nest by throwing out the sticks used by the male bird one at a time. After choosing a nesting site the female wren then takes over the construction and makes a nest cup over the pile of sticks made by the male bird. Materials used by the female wren to line the nest are soft material like feather, hair, wool, spider cocoons, strips of bark, rootlets, moss, and trash.
The House Wren is known for its eccentric choice of nesting site. The choices made by the female birds are so varied that until now there is specific type of nesting site that is cited in any literature as a typical nesting site of house wrens. Generally though house wrens choose to nest in natural cavities (though they also frequently use nest boxes) that are shaped so as to provide enough concealment for the nest. Usually it is only the entrance of the nest that is not hidden. Some examples of the more bizarre nesting sites chosen by wrens include cow skulls, flower pots, tin cans, boots, scarecrows, and the pockets of hanging laundry. The nests of house wrens are also usually found near the ground but can also be found high up in trees as well, especially in the mountains.