Earth Notes: Clark’s Nutcracker

Oct 4, 2017

Explorers Lewis and Clark, in Idaho in the early 1800s, observed dapper grey and black birds ripping into pine cones for the seeds. William Clark mistook them for woodpeckers, but Meriwether Lewis correctly identified the species as a cousin of crows, ravens, and jays. Still, ornithologists named the bird Clark's nutcracker. 

Clark’s nutcracker
Credit Eugene Beckes

Two centuries later, scientists are still interested in this bird and its passion for pine seeds. That's because a single Clark’s nutcracker can gather more than 90,000 seeds in a year, stashing them a few at a time in shallow holes in the ground. Months later the birds remember the locations of most of their stashes and return to retrieve them. Those they don’t find sometimes sprout into young tree saplings.

Many pines have small seeds encased in papery membranes and are dispersed by wind. Whitebark pines use a different trick. They “bribe” Clark's nutcrackers with jumbo-sized nutritious seeds, and the birds reciprocate by planting the seeds in perfect spots.

Bristlecone pines, the world's oldest trees, may also benefit from the birds’ activities. Scientists in Utah have learned that some bristlecones with multi-stemmed trunks have grown from several seeds cached together by Clark's nutcrackers, high on windswept ridges where it’s too cold for wind-dispersed seeds to germinate on top of the soil.

These are yet more twists and turns in this wonderful coevolution story—tree feeds bird, while bird plants tree.