Mud, Spit and Patience


One of the things that makes birds endless fascinating to WC is the whole matter of bird nests. Some birds get by with a scrape on the ground. Others build elaborate shelters to incubate their eggs and raise their kids.

In the latter group is the Cliff Swallow.

Cliff Swallow, Centennial Marsh, Idaho

Cliff Swallow, Centennial Marsh, Idaho

Cliff Swallows are very widely distributed in North America. WC has seen nest colonies along the Canning River canyon, north of the continental divide in Alaska; in Cave Creek in Chiracahua Mountains in southern Arizona, under the eaves of buildings in Chicago and in coastal Texas. They are easily identified by the white “headlight” on their forehead.

Cliff Swallows build nest out of mud daubs, laboriously collected and stuck together.

Building a Cliff Swallow Nest, Step One

Building a Cliff Swallow Nest, Step One

A newly built nest begins as a narrow mud ledge affixed to the wall, positioned between 10 and 12 cm below the overhang or lowest tier of existing nests. Birds add to the ledge until it is a crescent shape projecting 2–6 cm outward. Each round glob of mud represents a flight to the source of the mud, collecting the a small drop, and then flying back. The male and the female both work at it. A nest represents thousands of trips.

Building a Cliff Swallow Nest, Step Two

Building a Cliff Swallow Nest, Step Two

They then extend the lateral and ventral walls upward to form a broad half-cup projecting 5–10 cm outward. These are colonial nesters, and often share common walls, as shown here.

Building a Cliff Swallow Nest, Step Three

Building a Cliff Swallow Nest, Step Three

A roof is added by doming over the sides, creating a complete retort projecting 15–20 cm outward with an entrance tunnel pointing downward by a turning down of the ventral lip. The result is a gourd-like nest, with a short, narrow tube entrance.

The bottom of the nest is line with a little grass, eggs are laid and incubation begins. The birds continue to work on the nest through the whole breeding cycle, making repairs and elaborating the nest.

Some folks think the muddy, messy process is an annoyance. But it enables bug-eating, especially mosquitoes. A liltle mud and bird poop is a small price to pay something that eats thousands of bugs a day.

Small Cliff Swallow Nest Colony on a Cliff, Page Springs, Malheur NWR, Oregon

Small Cliff Swallow Nest Colony on a Cliff, Page Springs, Malheur NWR, Oregon

While they certainly net on manmade “cliffs, their preference is for the natural kind, which gives the species its English name.

Just another reason why birds are cool.

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