COMPONENTS TO CONSERVATION: BANK SWALLOW POPULATION TRENDS IN TWO LONG-TERM STUDY REACHES ALONG THE SACRAMENTO RIVER
|Kaitlin Kozlowski; California Department of Fish and Wildlife; firstname.lastname@example.org; Jeffrey McFarland|
Bank swallows (Riparia riparia) are a migratory species of passerine which were listed as threatened in California in 1989 due to habitat loss. These birds nest in colonies in nearly vertical eroding cut banks, and are commonly found along streams as well as in coastal bluffs and upland sites. Surveys along the Sacramento River from 1986-2021 provide the most comprehensive monitoring dataset for this species within the state. While sections of the river between Keswick to Red Bluff (Reach 1) and Colusa to Verona (Reach 4) have large gaps in monitoring data, these areas contain significant concentrations of bank swallows and are important for conservation. Reach 4 is the most heavily altered reach of the Sacramento River, containing vast stretches of revetment and providing valuable insight into how bank swallow colonies are affected by human-altered landscapes. Over the last 35 years, bank swallow burrows in Reaches 1 and 4 decreased, as did the number of colonies in Reach 1. In Reach 4 the number of colonies increased, but the reach also had a higher percent decrease in number of burrows, potentially due to greater habitat loss and fragmentation leading to an accelerated decline.