Although the sensuous whitebark pine can endure harsh, high-elevation landscapes, it depends on a single avian species for procreation – the Clark’s nutcracker. That relationship functioned well until outside factors started weakening, and in some cases decimating, the pine stands.
“Over the decades, we’ve seen huge, heartbreaking die-offs,” said Anya Tyson, citing mortality rates of 50-80 percent in some places.
Yet there are efforts to rescue whitebarks, one involving the collection of cones from healthy trees and the other involving volunteer citizen-scientists whom she’s recruiting. A field naturalist in Lander, Tyson delivered a presentation called “Whitebark Pine and Clark’s Nutcracker: Symbiotic Soulmates at High Elevations” in Cody on June 12, sponsored by the Greater Yellowstone Coalition and opening GYC’s 2017 Cody Science Series.
“An aesthetically beautiful species,” the whitebark can live up to 1,000 years, Tyson said. “It grows in high, rugged, beautiful landscapes. It’s a keystone species,” which plays a critically outsized role in the ecosystem.
It’s also an “obligate,” she added, meaning the whitebark depends on the Clark’s nutcracker to extract the seeds from its pine cones that grow on the tips of its branches. “Its cones don’t even open” and will fall to the ground and rot unless they’re opened by the nutcracker.
“That bird is designed to shred cones,” Tyson explained – shred and spread, it turns out.
The nutcracker can live up to 17 years and is quite efficient, with a pouch under its tongue that can hold up to 150 seeds, she said. It flies around and buries seeds, mainly about 1-2 inches below the surface.
“The Clark’s nutcracker can memorize 10,000 locations in a season” by triangulating sites and distances, Tyson noted. And “it can cache 30,000-98,000 seeds in a season.
“That’s how the whitebark pine is spread on the landscape. This modest bird is a huge player.”
The whitebark grows at and above 8,000-9,000 feet and produce a high-calorie seed, containing more energy per ounce than chocolate. Like that sweet, the seed attracts numerous consumers – black and grizzly bears, red squirrels, fox and 30 bird species.
Grizzlies will raid middens created by squirrels and tend to stay high and out of trouble in years of good seed production, causing a decline in their mortality, Tyson noted. When the cones ripen in late August/early September, stands become “alive with activity – like a Disney wonderland,” she said.
A “pioneer species,” whitebark produce seeds so rich that they can germinate in poor soil, providing habitat for other species, Tyson continued. It also grows as krumholtz – clumps of stunted, deformed vegetation – holding the fragile soil and protecting the snow.
“When the snowpack is anchored and shaded, it persists longer into the summer months,” she said, thus “this species has an effect on our watersheds.”
Accompany those positives is the negative of the current situation, Tyson said -- “The whitebark pine is in a steep, steep decline.” Two invaders are assaulting the tree, white pine blister rust and mountain pine beetle. She explained that when the rust sickens the trees, they respond by oozing sap – “like Kraft macaroni and cheese powder” – which attracts porcupines that girdle and kill the tree. Meanwhile, warmer temperatures have allowed the pine beetle to move to higher elevations and into whitebark stands.
“I fear we’ll see more stories like that if we don’t curb climate change,” Tyson noted.
In an attempt to counter the loss, Forest Service and Fish and Wildlife Service teams are collecting cones from “plus trees” that resist the fungus and raising a generation of resistant trees. The project can produce 200,000-400,000 seedlings per year, she said.
Still, the question remains whether the nutcrackers can survive the whitebark’s die-off and the subsequent loss of its high-caloric seed. By comparison, the seed of another high-elevation tree, the limberpine, provides about half the calories of a whitebark’s. Tyson cited one trend indicating nutcrackers don’t breed when cone crops are low.
“Yet it’s a tough, resilient bird,” Tyson added.
The nutcracker remains healthy in the Wind River Mountains and also populates western landscapes from the Southwest to Canada. But Tyson remains doubtful that it will ever reclaim the extent of its former mountainous range.
With ongoing studies to measure the high-elevation population, Tyson called on citizen scientists to report sightings and help determine if the nutcrackers are seeking other sources of food. Spotting the bird, sometimes called a “camp-robber,” is simple.
“It’s easy to identify,” Tyson said. “It’s independent, noisy, bold and conspicuous.”