RESOURCE USE, BEHAVIOR, AND DIET OF A SYNANTHROPIC PREDATOR, THE COMMON RAVEN, AND IMPLICATIONS FOR CONSERVATION OF A THREATENED SHOREBIRD

Janelle Chojnacki; Cal Poly Humboldt; janelle.choj@gmail.com;

Common ravens (Corvus corax) are intelligent, synanthropic predators with populations increasing throughout their North American range. Growing raven numbers and densities has intensified predation risk for many protected species, including the federally Western snowy plover (WSP, Charadrius nivosus nivosus). The breeding population of WSP in Northwestern California has continued to fall below recovery goals, and nest predation by ravens is the dominant direct cause of WSP reproductive failure. Using GPS units to track raven movement and resource use, behavioral surveys of beach-going ravens, and stable isotope analysis to examine raven diet, we are seeking to inform raven management strategies around WSP nesting areas. Results from GPS data reveal a multitude of small and large-scale food resources accessed by beach-going ravens, suggesting strategies utilizing outreach and education and assisting agricultural operations with raven deterrence may be beneficial in reducing raven density locally. Behavioral surveys indicate a lack of correlation between raven numbers and risk of WSP nest predation, suggesting that a few specialized ravens are responsible for WSP nest predation and indicating a targeted raven hazing approach may be most effective where appropriate. The impact of avian influenza which began in Fall, 2022 and served as a sort of natural removal experiment will also be discussed.

Poster Session   Student Paper