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Cliff Swallows a Springtime Attraction

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Throughout Spring, observant visitors are greeted by Cliff Swallows nesting under the eaves of the Visitor Center. The distinctive nests are built in dense clusters; at our Visitor Center they are usually found under the peak of the roof line. Each nest is a fully enclosed bowl with a tunnel out one side (single, cup-shaped nests on the building without a tunnel belong to Barn Swallows). The small beads of mud that make up the nest each represent a trip by the bird to and from a mud source, and each nest contains anywhere from 900 to 1,200 of these beads. Amazingly, the nests are constructed in just one or two days.

From the parking area, visitors can consistently spot swarms of swallows overhead. Barn Swallows, Tree Swallows, and Violet-green Swallows in addition to Cliff Swallows all can be seen. Barns Swallows have long, forked tails, Tree Swallows are dark blue on top with a white belly, Violet-green are similar to Tree Swallows but with a pronounced white patch atop the rump, and Cliff Swallows are rusty orange with a bright white stripe across the forehead. This bright white stripe can be seen like a headlight as the birds fly and also as they peer out through the tunnels of their nests.

Within the colony, a swallow may lay some of its eggs in another swallow’s nest, or may move an egg by carrying it in its beak. This swapping of eggs has the benefit of maintaining genetic diversity within the population; when a nest is predated, the loss of life is usually complete, but if the eggs have been dispersed among several nests in several locations, some of the offspring will still survive. The most common predators at Nisqually are owls. Throughout the summer, visitors are sometimes greeted in the morning by the somber sight of nests knocked from the eves, torn down by the owl in order to gain access to the chicks within. The Refuge will never destroy swallow nests, but predation by owls is natural and we do not interfere.

As one might expect of an animal that chooses to live in dense colonies, Cliff Swallows depend on one another – birds follow each other to food, and when a swallow finds a new insect swarm it will call back to other swallows to show them the way to the food source. But they also have a strong familial bond. After chicks have fledged and when the young congregate in large groups, a mother can still easily locate and identify her young; it is thought they do this primarily by voice, though the complex facial markings may also play a roll.

During the spring and summer months, Cliff Swallows may be the most oft photographed species at the Refuge. Visitors pause for a long time to peer up at the impressive nests. It makes sense that Cliff Swallows should be so popular: They are very visible, and we can see their struggles. But that we find them so endearing may be, on a deeper level, even more so because we intuit some similarity between their complex behaviors and our own.

Last Updated: May 31, 2013
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