Large-scale riparian restoration and agriculture: Ecosystem services and habitat buffers?

Large-scale watershed restoration is essential for improving water quality, and restoring species and ecosystem services, but the landscape-scale effects of restoration projects are often unknown. While riparian forest birds increase in abundance and species richness following riparian forest restoration along the Sacramento River in California, little is known regarding bird use on other parts of the riparian landscape. Orchards cover a large part of the Sacramento River landscape, and insectivorous bird use of these orchards could have positive or negative agricultural and conservation effects. I investigated bird use of orchards along 160km of the Sacramento River during winter 2006, conducting point counts and foraging observations on 23 orchards either adjacent to remnant riparian forest, restored riparian forest (>5yrs old), or other orchards, and 0m, 200m and 400m away from the adjacent habitat. Twenty-three riparian birds species were observed on the farms, with a trend toward a higher abundance and species richness of insectivorous birds foraging on orchards adjacent to restored habitat (p>0.05). Four of the riparian insectivorous species that were most abundant on the farms have been shown to be predators of codling moth, one of the major pest species on these farms. Increased abundances and species richness of insectivorous birds foraging on farms in the riparian areas, particularly in winter when danger from farm activities is low and the birds have large feeding ranges, indicate that farms may act as buffer areas for the riparian birds, and that bird use can provide an ecosystem service for the adjacent farms.