| Primary cavity-nesting birds serve as ecosystem engineers and play a vital role in the cavity-nesting bird community by excavating cavities in dead tree limbs and snags. I surveyed restored riparian woodlands to assess their ability to accommodate cavity-nesting birds as compared to remnant woodlands. This study provided clear information about 1) what age restored forests in California's Sacramento Valley begin to accommodate cavity-nesting bird species by providing large, mature trees and snags suitable for nest-excavation, 2) if the restoration forest planting scheme has an effect on the vegetation structure over time that may encourage or discourage cavity-nesting bird colonization, and 3) if remnant forests can be used as a reference for restoration success in regard to the cavity-nesting bird guild. I found that remnant forests harbor more naturally formed cavities, that Fremont Cottonwood (Populus fremontii) is a critical source of nesting substrate for excavating species, and that restored forests do not provide suitable nesting habitat until they have reached a minimum of 13 years post-planting. However, bird species richness was similar in all habitats, indicating that though younger forests may not provide nesting habitat, they provide other resources such as food and cover. |