AVIAN RESPONSES TO RESTORATION: NEST-SITE SELECTION AND REPRODUCTIVE SUCCESS IN SONG SPARROWS

Abstract

Riparian habitats typically support high diversity and density of both plants and animals. With the dramatic loss of riparian habitats, restoring them has become a pri- ority among conservation practitioners. Diversity and density of avian species tend to in- crease following riparian restoration, but little is known about how restored habitats func- tion to meet particular species' needs. Habitat structure is an important factor affecting species diversity and density and can influence nest-site selection and reproductive success. To evaluate habitat restoration, we examined interactions between habitat structure, nest- site selection, and nesting success in Song Sparrows (Melospiza melodia) nesting in restored, mature, and young naturally regenerating stands of riparian forest. We found that stand types differed markedly in structure, and that habitat structure influenced both nest-site se- lection and rates of nest loss to predation. Comparison of habitat structure among the three stand types indicated that restored stands offered fewer acceptable nest sites and poorer protection from nest predation. Concordant with those differences in habitat structure, Song Sparrows showed trends toward less density in restored stands than in mature forest, and had poorer nesting success as a result of predation. Received 26 August 1999, accepted 27 No- vember 2000.