This article was originally featured on Undark.
Twice each year, members of a subspecies of red knots—salmon-colored sandpipers—migrate thousands of miles between their wintering grounds in northern Mexico and breeding sites in the Arctic tundra, encountering myriad obstacles along the way. Thought to migrate during both day and night, brightly lit cities likely disrupt their nighttime journeys, and rising sea levels and invasive species threaten the wetlands they rely on for refueling at stopover sites.
The red knot is one of some 350 North American bird species that migrate. Yet there remains much to learn about the details of their journeys. It’s a critical information gap given the loss of an estimated 3 billion birds in North America since 1970, according to a 2019 study.
“The only way to think about conservation of migratory birds is to consider their full annual cycles,” including their migration routes and wintering sites, said Bill DeLuca, a senior migration ecologist with the National Audubon Society.
The problem, he said, is “We don’t know, for a lot of species, what time of the year is causing the declines.” For the vast majority of migrating birds, the full picture of their life cycle is incomplete, DeLuca added.
That’s partly due to technology. Until recently, while scientists could study birds at their North American breeding sites, they had few ways to track them individually throughout their migrations or while in their wintering grounds, especially small songbirds like warblers and sparrows.
And for birds that migrate through the West’s remote deserts and mountains and across its wild shorelines, like the rufous hummingbird, which journeys between Alaska and the Pacific Northwest and Mexico, their flight routes are even less understood. “Knowledge of migration patterns for birds in the West is way behind the East,” said Mary Whitfield, research director at the California nonprofit…
Read the full article here