Chasing Summer and Insects: Barn Swallows Return

Posted by: Karen Stevenson, Woodland Park Zoo Volunteer; additional contributions by Gretchen Albrecht, Zookeeper and Anna Martin, WPZ Volunteer

Photo by Gretchen Albrecht/WPZ.

Just a few weeks back, the memo came through. It read only, “They’re back!”

“They” are barn swallows, Hirundo rustica, and we’re celebrating their return. Here in the Pacific Northwest, barn swallows are harbingers of spring’s longer, warmer days. Warmer days awaken long-dormant insects, and barn swallows—like most little insectivores—follow their food (mostly flies and mosquitos, but also beetles, bees, wasps and so on). They summer here, then when “summer” moves south, they do too, following available food all the way to northeastern South America and the Caribbean basin.

Barn swallows are comfortable in our big cities, small towns, neighborhoods and farms. While other swallow species prefer to nest in natural structures hidden from view, such as cliffs or tree cavities, barn swallows build mud nests out in the open so we can see the entire nesting cycle. Any straight-edged overhang will do: it might be tucked under a bridge strut, a porch, a roof overhang or a barn rafter. (Hence their clever common name.) They nest under piers, on boats, and at Woodland Park Zoo, especially in the Family Farm’s cow barn and at the Raptor Center. Once they’re settled into a nest, if all goes well, they’ll likely come back year after year, raising one or two broods before chasing summer south at the first signs of fall. They usually leave by late September.

Photo by Gretchen Albrecht/WPZ.

We love barn swallows. With dark purple backs, almost golden breasts and deep forks in their tails, they’re beautiful. They sing a soft, twittering warble. They swoop and soar. And they eat bugs, thousands of them. More importantly, barn swallows are an environmental indicator species (consider them cousins to the canary in the coalmine). Barn swallows give us clues to the overall health of the environment as food and weather influence their migrations and populations. 

Close-up look at a geolocator on a barn swallow. Photo by Ryan Hawk/WPZ.

We are at the far northern reach of the barn swallows’ natural range and because populations shrink from the edges, we’re in perfect position to collect data on changes—and we’re beginning to see them. Fewer swallows nested on zoo grounds last summer than the year before and if you look back just a few years, you can track a gradual decline in active nests. We don’t yet know if the barn swallow populations are in decline, if the birds are simply nesting elsewhere in the vicinity, or if their range is moving south, but we’re eager to learn more. 

Four years ago, raptor keeper Gretchen Albrecht and docent Anna Martin, who have been monitoring WPZ’s barn swallows for years, began working with researchers to track the migration of our summer barn swallows. The Migratory Barn Swallow Tracking Project, part of the zoo’s Living Northwest conservation program, tracks the birds by putting identification bands and tiny geolocators on the swallows that nest at the zoo. When the birds return the next season, the team removes the geolocators and analyzes the data, which tells the story of the birds’ migration. 

Photo by Ryan Hawk/WPZ.

With that data foundation, researchers overlay weather and agricultural details (especially related to pesticide use) and begin to put together an understanding of the factors influencing the changes in our local barn swallow populations. The project continues today, and for the foreseeable future too. The memo, “they’re back” was great news.

So if the swallows have returned to their nests at the zoo, we hope that they’ll soon be settling elsewhere in the region. If you see a mud nest in your carport or barn, please don’t take it down. It may be a new home for a barn swallow family. (If the idea of barn swallow poop bothers you, place newspapers or cardboard beneath the nest and popular perching spots to help keep things tidy.) 

There are other things you can do too:

• Avoid pesticides and let the birds help control insects naturally
• Join a citizen science project to help clean up a park or waterway to provide habitat for birds.
• Donate to a conservation project that helps protect local wildlife or vote for the Living Northwest projects at the zoo’s Quarters for Conservation kiosk next time you visit the zoo. (Be sure to ask for a token at the gate.)