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The mission of the Symposium of University Research and Creative Expression (SOURCE) is to provide a university-wide forum for Central Washington University (CWU) students, encouraging equity, diversity, and inclusivity, representing all disciplines and experience levels, to present their mentored research, scholarship, and creative works in a juried environment that meets professional conference standards and expectations.

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Wednesday, May 18 • 11:30am - 11:45am
Evaluating variation in Clark’s Nutcracker (Nucifraga columbiana) relative diet using feather stable isotopes

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The Clark’s Nutcracker is a bird with a mutualistic relationship with whitebark pine (Pinus albicaulis), a keystone tree species currently threatened by mountain pine beetles, climate change, altered fire regimes, and white pine blister rust. White pine blister rust is an invasive fungus introduced in the 1910s which attacks five-needled white pine species, including whitebark pine. Previous research indicates the nutcracker relationship with whitebark pine may be detrimentally impacted by the invasive fungus. However, no previous research has been able to compare diets before and after the introduction of blister rust. Using feather stable isotopes from museum specimens, I analyzed dietary information to address shifts in relative diet over seasons, life stages, habitats, and over the last 128 years. Shifts between seasons within each of these years showed significant increases in trophic level during the summer and decreases in trophic level during the spring and fall seasons. Adults also appeared to utilize conifer seeds more often than juveniles, even during the summer season. Over the years, there is evidence of diet shifts that may indicate a change conifer species preference, yet no significant changes in their relative trophic level. My project relates to whitebark pine conservation through examination of nutcracker diet shifts based on impacts of fire exclusion, climate change, and invasive species over the years and the seasonal stability of nutcracker-conifer relationships.


Jasmine Ruiz

Graduate, Biological Sciences


Alison Scoville

Mentor, Biological Sciences


Wednesday May 18, 2022 11:30am - 11:45am PDT
Student Union & Recreation Center (SURC) - Ballroom D

Attendees (1)