Clark's Nutcracker and Whitebark Pine

PNW Pacific Northwest Research Station INSIDE How Effective Are the Birds? ............................... 3 Strong Home Ties .................................................. 3 Helping the Birds .................................................. 5 FINDINGS issue one hundred thirty / february 2011 “Science affects the way we think together.” Lewis Thomas Clark’s Nutcracker and Whitebark Pine: Can the Birds Help the Embattled High-Country Pine Survive? “I saw today a Bird of the woodpecker kind IN SUMMARY which fed on Pine burs its Whitebark pine inhabits some of the bill and tale white Lorenz Teresa most pristine high-elevation areas the wings black every other of the West. Despite being protected part of a light brown, and from direct human influence, the tree about the size of a robin.” is declining from indirect effects of –William Clark, Lemhi Pass, fire suppression and climate change. Aug. 22, 1805. As a keystone species, its decline has widespread ramifications. Success- hitebark pine (Pinus ful restoration requires understand- albicaulis) is found on ing the behavioral ecology of Clark’s W the cold, steep, wind- nutcracker, a bird that plays a key role lashed ridges of the high northern dispersing whitebark pine seeds. Rockies, Cascades, Olympics, Until now, little quantitative informa- and eastern Sierra Nevada. Its tion existed about the nutcracker’s gnarled forms are a familiar sight home ranges, seed transport habits, to mountain climbers and high- and caching behaviors. A team led by country backpackers. Whitebark Teresa Lorenz, a master’s student at pine requires full sunlight to Utah State University, and collabora- germinate and thus is an early tors Martin Raphael and Carol Aubry colonizer of burns and other of the USDA Forest Service, used radio disturbed sites. At lower eleva- telemetry to track the movements of tions, it is found intermixed with 54 Clark’s nutcrackers in the Olympic lodgepole pine and Douglas-fir. and Cascade Mountains over three sea- Near treeline, it occurs in small, Researchers fitted Clark’s nutcrackers with radio tags to study sons. They found that about half of the scattered, nearly pure stands. their role in distributing seeds from whitebark pine and caching the seeds in sites where they might germinate. birds gathered seeds from outside their home ranges and that some flew up to “Whitebark pine is a sentinel species in the The tree has never been important commer- 20 miles to forage, much farther than high-mountain ecosystem,” says Martin cially, and because it grows in the remote previously reported. Most seed was Raphael, research wildlife biologist at the reaches of the West’s high country, it has been cached in microsites where it could not Pacific Northwest (PNW) Research Station. sheltered from direct human influence. Yet germinate. Nutcrackers also collected Raphael recently collaborated on a study ex- whitebark pine is in trouble—it’s experienc- ponderosa pine seeds and were more amining how the food-gathering efforts of ing declines of 45 percent across some of its effective in dispersing these to suit- Clark’s nutcracker (Nucifraga columbiana), range, says Raphael. “We’re seeing tremen- able sites than they were in dispersing a crow-sized bird with a strong, sharp beak, dous mortality from the mountain pine beetle, whitebark pine seeds. This information help whitebark pine regenerate. “The tree which seems to be associated with climate can be used to focus restoration efforts, plays a major role in mediating microclimates change. The two go hand in hand: because and may help managers refine seed- for other plants and animals, and its seeds are warmer temperatures are putting stress on zone boundaries and identify the likeli- tremendously important in the diets of not the trees, that makes them more susceptible est regeneration sites. only the nutcracker, but grizzly bears, ground to beetle attack.” squirrels, and jays,” Raphael explains. Fire suppression is the underlying dynamic that set the tree on its current course. KEY FINDINGS Historically, whitebark pine thrived in the mixed-severity wildfire regime that once pre- • Clark’s nutcrackers foraged widely for whitebark pine seeds but transported nearly vailed. Severe stand-replacing fires enabled all of them back to the home ranges for caching. Thus natural regeneration should the pine to colonize burned lands; light sur- be more abundant within nutcrackers’ home ranges than outside them. face fires killed understory spruces and firs and gave the young pines a competitive advan- • Nutcrackers transported seeds over much longer distances than previously observed. tage. With less frequent fires, spruce and fir The caching and germination of seeds from distant trees might produce even more gained a toehold, and they are now on their genetic mixing in whitebark pine populations than previously known, resulting in way toward supplanting whitebark pine across greater homogeneity across the landscape. much of its lower elevation range. White pine blister rust and mountain pine beetle are attacking the stands that remain. • Nutcrackers also collected and cached ponderosa pine seeds. In fact, the birds were more effective dispersers of ponderosa pine than whitebark pine, placing more The pine’s large, nourishing seeds feed many ponderosa pine seeds in habitats and microsites where they were likely to grow. wildlife species, notably the Clark’s nutcracker, which propagates the tree by caching • Nutcrackers cached most seeds of both whitebark pine and ponderosa pine in its seeds in the ground. Other species that eat unsuitable habitats for germination. the seeds include woodpeckers, jays, ravens, chickadees, nuthatches, finches, chipmunks, tree and ground squirrels, and mice. The seeds says wildlife biologist Teresa Lorenz, who aren’t retrieved germinate, initiating the next also provide autumn food for grizzly bears has uncovered valuable new information on generation of whitebark pine. and black bears, especially in the Rockies; the bird’s foraging and seed-caching habits. The bird’s range is about three times as large whitebark pine communities near Yellowstone Advised by Raphael, Lorenz conducted her as that of the trees, and its varied diet includes National Park and in northeastern Washington research while a master’s student at Utah State other conifer seeds (nutcrackers are particu- are designated as critical grizzly bear habitat. University. larly fond of ponderosa pine), insects, spiders, The tree’s cones are indehiscent—they don’t To cache their seeds in the ground, the birds and even small mammals and amphibians. open in the fall as do the cones of most other swipe a shallow trench with their bills and So the nutcracker apparently doesn’t need the pines. In a fascinating co-evolved relationship, deposit them. They also cache seeds above- whitebark pine to survive, but the tree does whitebark pines are propagated by the Clark’s ground next to rocks, among tree roots, near seem to depend on the bird. Although other nutcracker. The nutcrackers flock around fallen logs or branches, and under slips of wildlife feed on whitebark pine seeds (squir- whitebark pine stands in autumn as the cones bark. The nutcrackers can cache thousands rels can pose major competition to the nut- ripen and use their sharp, strong bills to ham- of seeds in a season and use their remarkable crackers), the caching of seeds by nutcrackers mer into the tightly closed cones and dig out spatial memory to retrieve them. After a year is the primary way—perhaps the only way in the seeds. “You can see the cone chips flying,” or two, some of the ground-cached seeds that nature—that whitebark pine seeds encounter soil in which they can germinate. Purpose of PNW Science Findings To provide scientific information to people who Teresa Lorenz Teresa make and influence decisions about managing land. PNW Science Findings is published monthly by: Pacific Northwest Research Station USDA Forest Service P.O. Box 3890 Portland, Oregon 97208 Send new subscriptions and change of address information to: [email protected] Rhonda Mazza, editor; [email protected] Cheryl Jennings, layout; [email protected] Science Findings is online at: http://www. fs.fed.us/pnw/publications/scifi.shtml United States Forest Department Service of Agriculture Whitebark pine is facing multiple threats across its range. In lower elevations, fire suppression has allowed spruce and fir to edge out whitebark pine. At higher elevations, white pine blister rust and mountain pine beetles are taking a toll on the pine. 2 HOW EFFECTIVE ARE THE BIRDS? iven the pine’s precarious status, let the birds take care of it? Evolutionarily, the ranges only in autumn to harvest seeds from the Clark’s nutcracker is a high- birds’ job was to reseed whitebark pine. How distant pine stands. These the researchers G priority study topic. Lorenz began her much can we rely on birds to do this work of classed as resident birds. The other half left research in 2006, conducting the first quanti- restoring?” the study area within a month or two of cap- tative study of Clark’s nutcracker habitat use ture and were classed as emigrants. From April 2006 to September 2009, Lorenz and cache-placement preferences. and her team captured and radio tagged 54 Nutcrackers do all their seed foraging and The question that guided her research, Lorenz nutcrackers at eight sites in the Olympic and caching during late summer through autumn, says, was, How effective are these birds in Cascade Mountains, and tracked the spa- as cones ripen. During this time, Lorenz’s regenerating whitebark pine? “If we have tial patterns of their foraging, caching, and team spent up to 7 hours a day, 4 days a week, stands that are dead or dying, should we plant nesting. They found that half of the birds watching individual birds, learning where seeds? Or plant seedlings? Or do nothing and remained year round near the capture site on they collected their seeds and where they fairly discrete home ranges, leaving these cached them.

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