Spring forward, fall back? Migrating birds may weather storms to reach breeding grounds

Fair-weather fliers may be braving stormy weather when love is on the line and on the clock, says new research from the University of Nebraska–Lincoln. Of the billions of birds that migrate annually, punching tickets for the tropics in the fall and northerly latitudes in the spring, the majority take to the skies only after the horizon has consumed the last slice of sun. And with good reason. At night, the flocking migrants often contend with less turbulence and fewer predators. But their nocturnal flight schedules can’t put them beyond the reach of another potential peril: thunderstorms.

Nebraska’s Matthew Van Den Broeke can spot the signatures of those migrating flocks on meteorological radar “pretty much every night” in the spring and fall, he said. A few years ago, the associate professor of Earth and atmospheric sciences realized that a recent advance in radar technology was offering an opportunity to meld his lifelong love of weather with his interest in ecology.

With help from graduate student Timothy Gunkel, Van Den Broeke set out to study how nocturnally migrating birds in eastern Nebraska, southern Indiana and eastern Iowa responded to isolated thunderstorms between 2013 and 2019.

More than 70% of the time in Nebraska and Indiana, meteorological radar revealed that the density of migrating birds was substantially lower in a thunderstorm’s wake — the stretch that the storm had just passed through. Van Den Broeke said the finding suggests that migrating birds in those areas may be going to the ground, or at least under the meteorological radar, to avoid danger when storms are overhead.

When the researchers compared the effect by season, though, they discovered a potentially telling difference: The reduction in density was measurably greater in the fall than the spring.

Read the full story from University of Nebraska-Lincoln here.