Or more accurately, the hurricane season?

There is such a bird, the veery thrush, that every year migrates thousands of miles from the northern United States and southern Canada across the Gulf of Mexico and the Caribbean Sea to South America. But there are two complications — the veery thrush only weighs about 30 grams, and the migration occurs during hurricane season. If such a small songbird runs into a hurricane… well, let’s just say it wouldn’t be good. Plus, every hurricane season differs in intensity and the number of storms.

So the verry thrush gives itself an edge. According to a study published in the journal Scientific Reports in 2018, for two decades these plucky birds accurately predicted the intensity of the hurricane season in the Atlantic Basin. During worse years, the birds would finish their breeding season sooner and begin their migration earlier. Conversely, during better years, the birds stayed longer in eastern North America.

To quote study leader Christopher Heckscher, an ecologist at Delaware State University, “Hurricanes occur at the same time they’re migrating. If they end breeding season early, they can get down there sooner. It makes sense that they would figure it out somehow.”

But how? “These birds are taking a cue from somewhere, and it could be something we haven’t discovered yet,” he says. So far, Heckscher hypothesizes the birds get their meteorological clues from their wintering grounds in South America, where the large-scale weather patterns that impact hurricane seasons form well before a hurricane appears. Exactly how the veeries’ “predict” hurricane seasons may be because of small changes in global cycles like El Niño and La Niña events.  With these seasonal changes, rainfall in veery habitat can vary, and during years when more rain falls, more fruit could be available, a major food source. The result of these rainfall fluctuations could be a reliable prediction for hurricane season. Thus a change in diet may help the veery return to North America in better shape, more capable of a longer breeding season. Conversely, with too little fruit, they may be driven by their lack of physical fitness to cut their breeding season short. 

If this sounds like a delicate balance, there are signs climate change is unbalancing it. These migration patterns form over thousands of years. Can migrating birds adapt quickly enough to these changes? Since 1966, veery thrush populations have declined globally by nearly a third. Plus their habitats at both ends are under the usual environmental and development pressures. “I’m pretty concerned about these birds,” says Hecksher. “They’re vulnerable for a lot of reasons.”

The complete article, “This Bird Can Predict the Intensity of a Hurricane Season. Here’s How.” by Sarah Gibbens is at https://www.nationalgeographic.com/environment/article/veery-thrush-bird-migration-predict-hurricane-season?