The Wonders of Spider Silk

Many tiny birds, including kinglets, Least Flycatchers, gnatcatchers, and several warblers, use spider silk in nest construction. The tiniest birds of all, hummingbirds, seem to specialize in using this sticky, stretchy material for their nests. Spider silk is extremely light and maneuverable, perfect for birds weighing less than two dimes to handle, and its stickiness helps hold nests tightly and securely against a leaf or twig.

Spider silk has another advantage for nesting hummingbirds: it’s strong and is one of the stretchiest materials known. It can stretch up to 40 percent of its length without breaking, allowing a hummingbird nest to expand with the growing nestlings.

First the nest serves as a deep, thick-walled incubator that fits tightly around the female to minimize heat loss as she incubates her two eggs. This nest shape also works well as a bassinet for the tiny nestlings. As they grow and move about, they stretch the nest into a slightly larger crib. Within 18 to 22 days after the eggs hatch, the nest has stretched to become a “big kid bed” holding two nestlings which have each grown almost as large as their mother.

—Laura Erickson