How Tiny Songbirds Survive Epic Migrations: Wind and Weather Patterns are Key

Songbirds can be tiny, weighing less than an ounce. Yet these birds migrate thousands of miles each year across the United States toward Central and South America. Now, scientists have discovered how songbirds accomplish this astonishing feat; it turns out that it's all about wind patterns.

"Most of what we've known about migration routes comes from ducks and geese," said Frank La Sorte, one of the researchers, in a news release. "But terrestrial birds are much smaller and they aren't reliant on the same kinds of habitats. There really isn't a narrow migration path for them, and they aren't necessarily in the same place in spring and fall."

In order to better understand the migration patterns of songbirds, the researchers analyzed thousands of sightings to develop, for each of 93 species, an aggregate picture of where a species is during spring and fall migration. These collective sightings gave scientists an indication of how and where the species were migrating. They then used computer models to sort species with similar movement patterns into groups.

So what did the researchers find? It turns out that most land birds fit into three main groups. There was a western group, a central group and an eastern group. Many of these land birds actually followed different routes in the spring and the fall, particularly in the east.

It turns out that the songbirds are less tied to a single habitat, like waterfowl; this means they can spread out more across the continent. Many species in the eastern and central groups took southbound routes far to the east of the northbound routes, resulting in a clockwise migration loop. In fact, these shifting routes showed that the songbirds were taking advantage of stronger tailwinds in spring and less severe headwinds in the fall.

"All these species migrate at night, at high altitudes, where we can't see them," said La Sorte in a news release. "But when the sun comes up in the morning they have to find somewhere to land. So any new knowledge about where they're traveling is valuable to conservation partners."