Epic Migrations of North American Birds

Dr. Autumn-Lynn Harrison, Smithsonian Migratory Bird Center. Credit: Mary Lewandowski, National Park Service.

by Delia O'Hara
AAAS

Autumn-Lynn Harrison, Program Manager of the Migratory Connectivity Project (MCP) at the Smithsonian Migratory Bird Center at the National Zoo, learned to love animal migrations as an undergraduate student at Virginia Tech, watching wildebeest pound across the Serengeti in Africa in their annual search for greener grass. Now, Harrison coordinates the MCP's ambitious efforts to discover a fuller picture of the lives of birds: Where do birds like the long-billed curlew or the broad-winged hawk, spend their winters? Where do birds we see in other seasons go to breed?

These questions are of an urgent nature as bird populations are facing steady declines around the world. Last fall, an alarming study showed that North America has lost three billion birds since 1970, about one-third of the total bird population. For Harrison, however, the study created new resolve around learning all we can about birds in hopes of saving them.

“Without that knowledge of where they go, we can't even begin to figure out where the impacts are” — or how to structure conservation efforts, says Harrison, an ecologist and conservation biologist.

The question of why some birds disappear for several months has intrigued humans for millennia. Europeans theorized that birds hibernated in rivers to survive winters, like frogs; or turned into other birds; or flew to the moon. Then, in 1822, a hunter shot a stork in northern Germany and discovered an African arrow embedded in its body. But the mysteries of the 40% of bird species that migrate are only now beginning to be unraveled. Electronic tracking, such as small devices that are attached to birds, and other technologies, have played a large role in this, Harrison says.

Early trackers used in the 1990s were so big that only large birds like albatross and eagles could fly with them, she says. Now, tiny GPS devices with solar-powered batteries are being fitted to much smaller birds.
The MCP has field projects all over the Americas to track migrating birds, working with graduate students and agency biologists, choosing species that little is known about, or that have markedly declining numbers — the common nighthawk, rusty blackbird and Connecticut warbler, to name a few. Harrison herself leads projects involving oceanic and coastal birds, often in Arctic North America, a natural fit for a biologist with a background in marine animals. One bird Harrison studies, the Arctic tern, travels from the northern tip of the world every year, to the southern tip, and back, which can be an annual journey of more than 44,000 miles, Harrison says.

Earlier in her career, Harrison studied the migrations of large oceanic predators like seals, sharks and leatherback turtles as part of the Tagging of Pelagic Predators project. In one study of 14 such species, her team looked at their relationship with the human societies they pass, and the various levels of protection they are afforded as they travel. She presented that study’s findings to participants of the United Nations First Intergovernmental Conference on Sustainable Use of Marine Biodiversity Beyond National Jurisdiction, in hopes of bolstering the chances of a treaty, still under consideration, to make migrating sea animals' journeys safer.

Harrison travels extensively for her research, and she will go back to that once the pandemic eases. This summer, though, there is a moratorium on travel.

So instead, “We have been able to take a breather, revisit the data we have collected, and tell some of the interesting stories,” she says.

One such story includes the first full-year tracking, held through 2019-2020, of the Pomarine Jaeger, a “gnarly” predatory seabird that breeds in the Arctic.

“We discovered that three closely related species of Jaegers nesting on the same island in the Arctic dispersed during migration to four different oceans to spend the rest of their year,” she says. “That's amazing to me.”
Harrison has also enjoyed returning to live near the Chesapeake Bay to work at the Smithsonian.  She grew up on the bay, on the Eastern Shore of Maryland, where her father's family settled in the 17th century and became “watermen”— solely oystermen until the collapse of the oyster population forced them to diversify into harvesting eels, crabs and other food animals in the bay. Harrison's parents were a math teacher and office manager of an electrical contracting company, but she spent time at her grandmother's house on Tilghman Island, “poking around in the marsh.” She knew early on she would be a biologist, but thought she would be an estuarine researcher, studying Chesapeake Bay.

And lately, Harrison has indeed had a chance to study brown pelicans in the bay with Dave Brinker of the Maryland Department of Natural Resources, who discovered their first nest found in Maryland, in 1987. Harrison's father came with her as a field volunteer on one trip, and it was “very special to have him involved,” she says.
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“I respect scientific knowledge so much,” she says. “But I got a different kind of education from people who got up at 4 am to go out to catch crabs. They know the bay, they know the animals, they know these systems. That's knowledge to respect, too.”

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