ETD

• Northern Range
• passerines
• songbirds
• willow
• Yellowstone

Riparian corridors dominated by willow in Yellowstone National Park’s
Northern Range have undergone major changes over the past century. After a long period
of suppression substantial willow recovery has been reported in the last thirty years. Willow corridors represent a key habitat: by providing nesting sites and trophic resources, they support a large fraction of Yellowstone’s avian diversity and are especially critical for a guild of willow-associated songbirds. Therefore, variation in willow conditions is expected to influence specialist’s abundance and community composition. This thesis examines whether the documented improvements in riparian willow condition have
resulted in detectable shifts in the temporal trends of riparian-associated songbirds within Yellowstone’s Northern Range. To address this question, I analyzed long-term monitoring data from the two Breeding Bird Survey (BBS) routes in the region, focusing on willow specialists identified in the literature. For each species, I assessed the presence and magnitude of a trend shift, and the delay in the response to the habitat change. To isolate local, riparian-specific responses from broader dynamics, I compared these results with overall avifaunal trends on the same routes and with regional trends for the same specialist species. Overall, this project aims to clarify whether riparian vegetation change
has reshaped songbird communities in Yellowstone’s Northern Range, contributing to the broader debate on riparian ecosystem restoration