Abstract
In California, oak woodlands are being converted into vineyards, resulting in a loss of songbird nesting sites. Although many vineyards contain wooded riparian habitat, no previous research has examined the avian species composition in oak-vineyard landscapes. We compared the avian communities associated with vineyard, edge, and riparian habitats and examined to what degree the riparian habitat in vineyard landscapes continues to support birds associated with native oak woodland habitat that spanned the region before agricultural intensification. We further tested whether the presence of nest boxes in vineyard and riparian areas altered avian species composition in the landscape. Mist nets were used to survey the avian community in vineyard, edge, and riparian habitat at four sites during the breeding season. Permutational ANOVAs, using presence-absence data from captures, identified habitat, study sites, and time over the breeding season as highly significant main effects that explained differences in species composition. Establishment of songbird nest boxes did not alter the species composition. Two-thirds of the birds identified as woodland species in prior studies were found in riparian areas adjacent to vineyards, including five watch-list species. Overall the species composition of birds using riparian habitat was greater and significantly different from those found in the vineyard. This highlights the importance of maintaining natural areas like riparian habitat in agricultural landscapes.