The whitebark pine needs a bird, the Clark’s Nutcracker, to plant its seeds. Now that a devastating disease threatens the tree, what happens to its fine-feathered friend?
The short plaintive cry of the Clark’s Nutcracker rattles through the pines of the high Cascades and Rocky Mountains like an impatient call for attention. Despite its powerful bill and white feathers adorning its wings and the tail, this bird, the approximate size of a robin, doesn’t look particularly special. But take the advice of any naturalist: Look closer. Pay attention. Perhaps it will become apparent that the Clark’s Nutcracker is now at the intersection of an ecosystem that is on the verge of unraveling.
First described by Lewis and Clark in 1805 journals, this bird “feeds on the seed of the pine and also on insects. It resides in the rocky mountains at all seasons of the year, and in many parts is the only bird to be found.”
Modern scientific studies corroborate Lewis’ observation: Clark’s Nutcracker feeds primarily on the seeds of the whitebark pine, a regal windblown tree that ekes a tenuous existence in the higher elevations. Using their long,chisel-like bill to pry open the cones and extract the pine’s seeds, these nutcrackers collect and stash the seeds in various locations, an important condition of the tree’s survival. The nutcracker collects and stores up to 100 seeds in its throat pouch at one time and then buries caches of the seeds in as many as 9,000 different locations. For those of us humans who have a hard time recalling phone numbers or misplaced keys, these birds’ ability to recall where their seeds are stored is impressive. Due to an enlarged region in the brain that dictates spatial memory, the nutcrackers use forest features such as downed logs to help them remember their storage sites. If the log is moved10 feet north, the bird will look for its seeds 10 feet north of where they really are. Because the nutcrackers never recover all of their seeds, they help plant the forest that in turn sustains them.
“They’re not bird brains, far from it,” laughs David Dalton, a Reed biology professor, as he sits looking at his office book shelf that is heavy with the 13 volumes of Lewis and Clark journals. Working on a book that applies modern bio-logical research to the findings of Lewis and Clark, Dalton is writing a chapter on the Clark’s Nutcracker because, he says, the mutually beneficial relationship of the pine and the nutcracker is “one of the more remarkable stories out there.”
Dalton and associate professor of biology Stephen Yezerinac also discussed the nutcracker in an MALS class they co-taught recently on “The Biological Legacy of Lewis & Clark.”
What’s fascinating according to Dalton is that the birds and the trees have evolved in a codependent relationship that would make any marriage counselor marvel. The nutcrackers thrive on the buttery-rich fat of the whitebark pine, but because the birds don’t eat every seed they harvest, they are also propagating. Whitebark pine seeds are heavy and thick— they can’t disperse in the wind or open on their own. Unless the Clark’s Nutcracker shatters the cone and buries the seeds, new trees won’t grow.In return for the favor, the rich seeds of the pine, the nutcracker’s primary food source, sustain it into late fall when other birds have already dropped to lower elevations, providing them with a uncontested niche.