The last egg

kw: nature, photographs, birds

This image, very close to life-size on a 100dpi monitor, shows the egg of a Carolina Wren that didn't hatch. As I wrote in early June, one of the nest boxes I keep track of started the season with five or six Wren eggs, and at least four nestlings fledged. A day or two after the fledglings left the next, we found a single egg in the nest. In hopes that the birds were trying for a second clutch, as they sometimes do, we left it alone.

That was two weeks ago. Today, that single egg was still there, and we concluded that it was one that never hatched in the first place. We cleaned out the nest box. This is the nest with its lonely, dead egg. But it provides a good record of the appearance of the egg. The eggs of Carolina Wrens usually have more definite speckles. This one is more nearly a smooth, graded beige-to-brown with the darkest brown at the large end. Five weeks ago all the eggs had this appearance.

I found it interesting that the wrens nearly filled the box with twigs before making a soft nest near the top. They really like the smallest cavity that will accommodate their brood, with no leftover. Maybe this discourages cowbirds, which would also have a hard time entering a box sized for bluebirds. The first time I saw a wren nest, I thought it was starlings; this was before we had a front with a smaller hole put on this nest box. But a colleague assured me that is how the wrens build their nests.