I surveyed the summer resident bird and butterfly populations at six sites in Santa Clara County, California (all former oak-woodlands) in 1992 and 1993 in order to examine the response of individual bird and butterfly species across an urban gradient and the concomitant changes in community structure. The survey sites run from relatively undisturbed to highly developed and include a nature preserve, recreational area, golf course, residential neighborhood, office park, and business district. The composition of the bird and butterfly communities shifts from predominantly native species in the natural area to invasive and exotic ones at the business district, with species richness, Shannon diversity, and bird biomass peaking at moderately disturbed sites. Butterfly abundance peaks at the most natural site--the biological preserve. The predevelopment bird and butterfly species--assumed to be those found at the most natural site--drop out gradually as the sites become more urban. These patterns are significantly related to shifts in habitat structure that occur along the gradient as determined by canonical correspondence analysis (CCA). These findings are generally applicable in the region based on one-day bird surveys of four more sites of each type of development. A comparison of these taxa suggests that butterflies and birds may serve as surrogates for one another in conservation planning for several community measures including species richness, Shannon diversity, and percent of original species at a scale of one to tens of kilometers. The effort expended to assess the butterfly community was approximately one-third of that used for the bird community which suggests that butterflies may be a useful indicator taxa when time and/or money are in limited supply. I used the Delphi technique to provide an initial ordering of the sites with regards to urbanization for gradient analysis. This ordering was confirmed empirically and repeatedly by the distributions of birds and butterflies at the sites, the changes in habitat structure, and the patterns of community response by both taxa. This suggests that the Delphi technique can be a useful method for conservation planning when information or time is lacking.