On the Pine and the Nutcracker

Whitebark Pine. By Walter Siegmund, via Wikimedia Commons

Here’s a story for a sleet-filled day, a day when you’re stuck in the car or at the airport, and your kids look up at you, expectant.

It begins with a tree. With limber and whitebark pines—trees that look so similar, they can be told apart only by their fist-sized cones. These trees are having a tough time these days, on the alpine slopes of the West, where they live. Beset by an invasive fungus called white blister rust and by bark beetles—both plagues encouraged by climate change—they’re dying throughout their range. On some slopes, most are brown and needleless, or if not, then lonely.

That’s not how the story ends, though. Because each year, those trees still alive offer up about 25 pine cones, as if to the air. As it turns out, they’re a crucial food source for squirrels, which horde them in middens, and for endangered grizzly bears, which raid these middens and gorge on the fatty pinenuts before hibernating. And what few seeds are left are gathered by one type of bird in particular—a Clark’s nutcracker—which slips each into a pouch, under its tongue, and flies.


Now, like all corvids, nutcrackers have an extraordinary memory, a knack for niches, so they bury those small, brown seeds on south-facing slopes. Warmed by the low sun, these slopes have less snow, and all winter, nutcrackers fly across those steep places, flashing black-and-white, remembering their many caches, digging up fat-filled nuts, as grizzlies sleep. But they forget a few, of course, and those seeds—planted serendipitously, but ecologically speaking, not in error—become trees: whitebark and limber pines that, if the world doesn’t warm too fast, might grow to be over 1,200 years old.

Twenty-five cones a year isn’t a lot, is it? So scientists rightly fear for the species. In Alberta, they’ve been searching for a rust-resistant strain to propagate in the region. But then, last summer, that region witnessed something amazing. Without rhyme or reason—or so it may seem—most limber and whitebark pines offered up three times their usual number of cones. Some 300 times more—300 times! It was a cornucopia of nuts no fantastical troop of squirrels, grizzlies, or nutcrackers could ever devour. The trees had stored up energy for years, and unleashed it, just when it was needed. There were plenty of seeds for the birds to wing off.

And so, with luck, a few more trees come spring, and another story.