There are almost 30 species of shorebirds that breed in the Canadian Arctic, and all are strongly migratory. Surely the longest of their migrations must count among the most impressive feats in the natural world. Red Knots, for instance, are only nine inches long. And yet, every year, they fly some 9,000 miles from their summertime Arctic nesting territories to their South American vacation hideaways—and then another 9,000 miles back again. Unfortunately, shorebird population are hurting across the globe. In North America alone, shorebird populations have plummeted by 70 percent since 1973, and among those, birds that breed in the Arctic are especially threatened, writes journalist Margaret Munro in a recent Nature feature. But a workable solution is hard to come by because the birds face a multitude of threats as they make their way across the Western Hemisphere. Munro writes: Although the trend is clear, the underlying causes are not. That’s because...