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Observations from June to September 1977 at a spring in central coastal California showed that 24 of 45 species of birds found within a 1.6-km diameter area used the spring as a source of free water. Color-banded individuals of several species drank more than once a day. A significant seasonal variation in the number of drinking visits per hour was found for all species combined. Only the Brown Towhee showed a conspicuous diurnal drinking pattern, however. Temperature on a particular day was not correlated with number of species visiting the spring, the total number of visits by all birds to the spring, or the number of visits by five of the six species considered to be water dependent. Granivory was significantly, positively correlated with water dependence. Permanent residents were more regular drinkers than summer residents, but this was a secondary effect resulting from the high proportion of granivory among permanent residents. The habitat surrounding the water hole, species abundance, and human disturbance at the spring all showed possible influence on our measures of water dependence. These findings suggest that surface water may be an important determinant of species distribution and community organization in mesic as well as desert environments.

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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 priority among conservation practitioners. Diversity and density of avian species tend to increase following riparian restoration, but little is known about how restored habitats function 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 selection 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.