House Wrens have nested in our yard for the past 10 years, using our nest boxes. Some years we’ve had two pair. I sat with a camera the other day watching what I presume was a male wren work on his nest. Male wrens will begin more than one nest, allowing the female of the pair to choose the site to be completed. I think this nest was nearing completion; the bird was carrying bits of grass and rootlets (see photo) to the nest, materials used to form the cup at nest bottom. This is a PVC box four inches in diameter. Last year the nest built by a wren slid complete from the box when I did fall housecleaning. Tension of interwoven sticks held the nest together. After photographing it I took it apart to count the sticks: 206 of lengths from about one inch to six inches. How to build a nest is instinctive for the bird. Unlike say a robin nest, most of which resemble one another, wren nests vary in style. I’ve seen nests open at the top. I’ve seen one where the entry tunnel spiraled down to the cup, like a spiral stairway. That nest was an engineering marvel. Nests must vary depending on the cavity used (wrens are always cavity nesters). But, does an individual wren build generally the same style nest each time? How does the bird select the sticks used? Search out a stick of a particular dimension for a particular use? Pick a stick at random, then see how to make it work once in the nest? I’ve never seen a wren reject a stick brought to the nest. Perhaps that’s why some nests are so jammed into the box that room for the hen and babies is surprising. The nest in the photo, the one I disassembled, was a work of art, another engineering marvel. I doubt if any human could have taken those sticks and made that nest.