Every year around November, flocks of one of North America’s tiniest geese leave Alaska’s Izembek Lagoon, launching an epic migration up to 3,000 miles long. In flights that can last 60 hours, Pacific brant head for eelgrass tidelands that stretch from British Columbia to Baja.
Many humans along the way consider these distinctive birds — black, with mottled flanks and a necklace of twisting white stripes — North America’s “best goose.” Uncommon and beautiful, they’re beloved by birders. Subsistence and recreational hunters prize them, too: They’re particularly delicious.
But much of their habitat is degraded, and their size and habits make them harder to study than other geese. As technology progresses, however — from tinier trackers to more powerful computing tools — researchers are learning more about what this species needs to survive and thrive.
Pacific brant breed along coastal Arctic and subarctic mudflats, but climate change and fossil fuel development are shrinking many of those areas. In 2023, U.S. officials estimated there were 108,000 brant West-wide — less than half their historic numbers.
Brant migrate in swarms, instead of Vs or lines, and behave similarly on land, moving together in tight knots.
Brant weigh about 3 pounds, making them closer in stature to mallards than Canada geese, which can reach 20 pounds.
Waterfowl population estimates are often based on banding and harvest data, but because nearly every Pacific brant spends autumn at Izembek, they’re uniquely possible to count. Since the ’70s, scientists have done this from the air, but low flights frequently disturb birds, and manual counts are hard to get right. In 2017, USGS scientists piloted a new, safer and more precise method: They captured images from high-flying aircraft, then trained AI to count birds.
Some populations face more threats than others, and genetic research is helping biologists target protections. For example, birds from multiple breeding sites winter in Washington. Most are black brant, many of which breed in Alaska, where a few colonies are actually growing. A rarer group, called gray-bellieds, nests at much higher latitudes in Canada. Recognizing subpopulations has enabled Washington authorities to restrict hunting in years when just one group’s numbers are low.
Researchers once tracked brant migrations by telegram, as Arctic scientists notified southerly colleagues when flocks left Izembek. More recent bird-mounted tracking tools were long limited by battery lifespan and weight. And brant present an added challenge: scientists use tracking collars on other geese, but brants wearing them are often socially ostracized. So researchers have developed other methods, such as implanted trackers and devices worn on a backpack-like harness. Some even use tiny solar panels, which allow for lighter, longer-lasting batteries.
These birds depend almost entirely on eelgrass, which development, diminished water quality and rising sea levels has degraded coast-wide.
Brant must eat enough eelgrass each winter to fuel their return flight to the Arctic and provide the stored energy they need to lay eggs.
Illustrations by Alex Boersma/High Country News
This article appeared in the December 2024 print edition of the magazine with the headline “Get to know the Pacific brant.”
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