Birds build nests of all sorts of materials

I have been watching a lot of nest building behaviors lately with the accompanying egg laying, incubation and subsequent feeding of the youngsters. The Eastern bluebirds in my nest box will fledge their chicks any day now. I have been watching barn swallows gathering mud to fashion a sturdy cup to be placed at someone’s front porch.

Last Sunday I watched a gray catbird carrying dried leaves into a thick hedge. Just a few feet away an American robin gathered earthworms until there was a thick mass of writhing worminess in her bill.

A few weeks ago I was tipped off about the location of a blue-gray gnatcatcher nest along Mallard Creek Greenway. I am always amazed at the intricacies of the nests that smaller birds build.

If you look closely you may see the spider web silk that anchors the 2-inch diameter cup to the bare tree limb. The adults fashion a nest of grasses and bind them tightly with the spider silk. As a finishing touch, lichens from nearby trees are stuck to the exterior, providing a superbly camouflaged structure that looks just like a knot on a limb. It is so well-hidden right in plain sight that the nest is often built before the leaves come out. Ruby-throated hummingbirds build their nests of basically the same materials.

Then there are the species that build no nest at all. Killdeer scrape out a shallow area in dirt or gravelly soil and lay their eggs right on the bare earth. The eggs are perfectly speckled to look like gravel. This allows the birds to build their scrape sometimes within a few feet of a busy walkway or in the center of a gravel parking lot. Maybe you have wondered why a killdeer stands its ground and voices displeasure with you as you walk by. There are surely eggs or young nearby.

Most of our permanent resident birds will rear two or even three broods in a season. The neotropical migrants may manage only one clutch. Watch for local birds taking care of family business now through midsummer.

This story was originally published May 14, 2015 at 3:52 PM with the headline "Birds build nests of all sorts of materials."