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Monitoring the Common Raven in Yosemite National Park
Root, John Steven
Root, John Steven
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Abstract
The common raven (Corvus corax) has expanded its population in many areas due to increased availability of anthropogenic resources. In Yosemite National Park, raven abundance has increased substantially since the 1960s, paralleling trends in human visitation and development. A 2010 study of ravens in Yosemite examined their status and foraging behavior, raising questions about their ecological impacts. Building on that study, we conducted transect point count surveys, foraging surveys, and focal-individual sampling during the summer of 2024 to assess raven abundance, distribution, and behavioral patterns throughout Yosemite National Park, California, USA. Ravens were significantly more abundant in high use frontcountry areas than in the backcountry, with Yosemite Valley supporting the greatest densities. Foraging surveys revealed complex behavioral interactions between ravens and humans, and found that ravens are more likely to be present at a site when there are humans actively eating. Focal-individual sampling of ravens found a strong association between ravens and human food, with 72% of observed successful foraging attempts involving anthropogenic food sources. Juvenile ravens spent a significantly higher proportion of time foraging than adults, while adults spent significantly more time resting. Comparisons with the 2010 surveys indicate that raven populations remain elevated compared to historical levels, reinforcing concerns regarding their potential impacts on native species. These findings highlight the importance of understanding human-raven interactions in conserved areas and suggest that management strategies addressing anthropogenic food sources may be necessary to mitigate potential ecological consequences of elevated raven populations in Yosemite National Park.