Project Summary

The Nature Conservancy (TNC) established the Cosumnes River Preserve with the mission to protect the Cosumnes River, the only undammed river that flows from the Sierra Nevada into the Bay delta, and the native plants and wildlife that depend upon it. The Preserve contains the largest remaining tract of mature valley oak riparian forest in the Central Valley. Recognizing the value of this relatively intact riverine system to wildlife, PRBO and The Nature Conservancy initiated a long-term songbird monitoring program in 1995 to evaluate the health of songbird populations persisting there. Monitoring activities encompass a variety of riparian and grassland habitats as well as evaluate songbird response to ongoing restoration.

Riparian Restoration

Riparian habitat restoration has been a primary objective of the Preserve and restoration sites of various ages include both cultivated (primarily valley oaks) restoration sites and process-based restoration (Fremont's cottonwood and willows) resulting from levee breaches along the Cosumnes River. Current habitat restoration at the Preserve is focusing on an ecosystem approach, relying on natural river processes such as flooding to restore the dynamic mosaic of riparian habitats that was historically present along the river. Levees that separate the river from its floodplain have been accidentally (1986) and intentionally breached (1995 and 1997) to allow flood waters to spread out over former agricultural lands. The Accidental Forest, primarily fremont's cottonwoods, resulted from the first accidental levee breach. The floodplain areas inundated from the 1995 and 1997 levee breaches are also regenerating naturally with stands of young cottonwoods and willows. To learn more about TNC's Cosumnes River Preserve please visit their website: http://www.cosumnes.org/

Objectives

• Maintain an inventory of bird species utilizing the Preserve for breeding and migration purposes within riparian habitats and restoration sites
• Evaluate and monitor the riparian bird communities within the Preserve to test the efficacy of restoration activities (bird response to different restoration techniques)
• To determine trends in relative abundance of species using the Preserve (long-term monitoring program)
• To assess any annual variation in importance (i.e., productivity) of different sites for breeding birds due to seasonal differences (e.g., level of inundation at sites and corresponding vegetation changes)
• To provide land management recommendations intended to maintain or restore healthy bird populations based on current monitoring results
• To contribute to national and regional conservation efforts by using standardized methodologies and contributing data to national monitoring programs (e.g., BBIRD and MAPS)
• To incorporate monitoring results into the state-wide Riparian Bird Conservation Plan (RBCP) of the Riparian Habitat Joint Venture (RHJV).

Focal Study Species

The Riparian Bird Conservation Plan for California designates 14 priority species recommended as focal species for research and monitoring. 10 of the 14 focal species are present at the Preserve during the course of the year including 5 breeding species: Common Yellowthroat, Black-headed Grosbeak, Blue Grosbeak, Swainson's Hawk and Song Sparrow. The 5 other focal species are neotropical migrants that use the Preserve as an important stop-over site during migration including Yellow Warbler, Swainson's Thrush, Warbling Vireo, Willow Flycatcher, and Wilson's Warbler. The Preserve also has nesting Hutton's Vireos (resident) and Pacific-slope Flycatchers (migratory), both of which have been extirpated as breeders from most of the Central Valley. The State-endangered Yellow-billed Cuckoo has also been recorded at the Preserve (2001).

New CALFED/UC Davis Collaboration

Beginning in 2002, PRBO has begun collaborating on an exciting new interdisciplinary study focusing on the re-connection of the river to its floodplain and the effects on productivity for the riparian food web. UC Davis research by Dr. Peter Moyle has shown that these inundated floodplain areas outside the river channel are important foraging areas for native fish (especially young of the year). PRBO data on songbirds as well as research by UC Berkeley on bat populations will provide critical information about the terrestrial components of the riparian food web.

Partners and collaborators:

Cosumnes River Preserve (a consortium of partners including Nature Conservancy, BLM, Ducks Unlimited, State Lands Commission, CA Depts. of Fish and Game and Water Resources), UC Davis and UC Berkeley.

For more information about songbird monitoring at the Cosumnes River Preserve, contact Jeanne Hammond at jhammond at prbo dot org or Julian Wood at jwood at prbo dot org.