Large-scale, long-term bird response to river restoration in California's Great Central Valley

Background/Question/Methods

In ecosystems that have been severely degraded, ecological restoration is needed to create the conditions necessary for the environment to support multiple ecosystem services.  The science and practice of restoration however remains relatively young and even information on restoration performance is lacking, especially for projects with multiple-benefit objectives. The Sacramento and San Joaquin rivers have been highly altered and only about 5% of the historic extent of riparian forest remains.  Many riparian restoration projects on these rivers are now over 20 years old and are of a relatively large-scale.  One objective of the large-scale, long-term restoration projects on these rivers is to increase the abundance and diversity of resident and migratory landbirds (passerines and near-passerines). We used point count surveys from the Central Valley Floodplain Forest Bird Survey to examine whether landbirds were responding to the riparian revegetation projects.  We compared survey points from revegetated, extant, and a random sample to evaluate bird response. 

Results/Conclusions

We found that a diverse community of landbirds was responding positively to the restoration work in on both rivers.  For the majority of species we examined, density increased as the restoration project aged.  In many cases, densities on the restoration plots were approaching those on the remnant ones and in some cases were even higher on the restored plots.  We also discovered increasing trends in density on the remnant plots suggesting that restoration may be having a positive net effect for landbirds throughout the region. Large-scale restoration on California’s two largest rivers is benefiting a diverse landbird community, which thus meets one of the objectives of the projects.