JACKSON, Wyo. — August marks the beginning of a period of foraging for black and grizzly bears as whitebark pine cones mature and go to seed.
Nancy Bockino, whitebark pine ecologist with the Northern Rockies Conservation Cooperative, tells Buckrail that cones that began growing in late May 2023 are currently completing their development.
According to the Grand Teton National Park Foundation (GTNPF), whitebark pine seeds are one of the most nutritious foods for bears in the Greater Yellowstone Ecosystem (GYE). The National Park Service (NPS) confirms the seeds are a high-energy food that are rich in fats, carbohydrates and protein, extremely valuable to bears fattening up going into fall before hibernation.
Notably, whitebark pinecones are “indehiscent,” which the National Park Service defines as not splitting open to scatter seeds once the cones are mature, as some other pinecones do. Bockino emphasizes the importance of the Clark’s Nutcracker to the extraction and dispersal of these seeds, what she calls a “critical and obligate mutualism.”
Bears must access the cones themselves and extract the seeds with their claws, lips and tongue. Red squirrel middens, or caches, on the ground provide access to the cones, but grizzly bears will also pull down branches to access cones. Some grizzlies and most black bears will also climb into trees to obtain them.
“Hikers should be particularly watchful for bears and exercise caution in the whitebark pine zone this time of year—around 8,500 to 10,000 feet elevation in the Tetons,” GTNPF writes on their website.
Bockino says whitebark seeds are about 52 percent fat, 21 percent carbohydrates and 21 percent protein by weight.
“Their large size, high nutrient content and durability make whitebark pine seeds a high-quality, concentrated and long-lasting food source,” Bockino tells Buckrail.
The University of Idaho (UI) says female bears in particular depend on the fat reserves for their winter hibernation, especially those preparing to give birth. UI research shows that female grizzly bears that make more frequent use of whitebark pine seeds reproduce at an earlier age with higher reproductive rates.
But the dependency of bears on whitebark pines surpasses the seeds’ nutritional value. UI also suggests that the high elevation and remote habitats of whitebark pine trees reduces human-induced mortalities.
“Studies have found that during years of whitebark pine crop failure, grizzly bears tended to utilize areas for foraging that were much closer to human habitation, and were therefore more likely to be killed by humans,” graduate student Kim Sager wrote for UI’s online publication.
Sager cites research that determines 2.3 times as many adult female grizzlies and 3.3 times as many sub-adult males are killed by humans during years without whitebark pine seed use.
Since 2022, whitebark pines have been listed as a “Threatened” species under the Endangered Species Act. In 2023, GTNP ramped up their efforts to protect the pines and the National Park Service signed a five-year agreement to restore the species.
Bockino tells Buckrail that since being listed, whitebark pines have seen increased conservation and planting efforts. However, she notes the two biggest risks to cone production continue to be the native mountain pine beetle to remaining cone-bearing whitebarks and non-native blister rust to all sizes and ages of whitebark pine trees.
Unexpectedly, Bockino learned through her research that blister rust can spread during a single rain event. With a number of variables, like spore stage, aligning with the rain, the necessary humidity is enough to spread the deadly fungus.
