Science Findings, Issue 130, February 2011. Clark's Nutcracker and Whitebark Pine: Can the Birds Help the Embattled High-Country Pine Survive

摘要

Whitebark pine inhabits some of the most pristine high-elevation areas of the West. Despite being protected from direct human influence, the tree is declining from indirect effects of fire suppression and climate change. As a keystone species, its decline has widespread ramifications. Successful restoration requires understanding the behavioral ecology of Clarks nutcracker, a bird that plays a key role dispersing whitebark pine seeds. Until now, little quantitative information existed about the nutcrackers home ranges, seed transport habits, and caching behaviors. A team led by Teresa Lorenz, a masters student at Utah State University, and collaborators Martin Raphael and Carol Aubry of the USDA Forest Service, used radio telemetry to track the movements of 54 Clarks nutcrackers in the Olympic and Cascade Mountains over three seasons. They found that about half of the birds gathered seeds from outside their home ranges and that some flew up to 20 miles to forage, much farther than previously reported. Most seed was cached in microsites where it could not germinate. Nutcrackers also collected ponderosa pine seeds and were more effective in dispersing these to suitable sites than they were in dispersing whitebark pine seeds. This information can be used to focus restoration efforts, and may help managers refine seedzone boundaries and identify the likeliest regeneration sites.