Interactions among American crows, breeding songbirds, and forest function, and their responses to urbanization

Land cover change, particularly the conversion of native forest habitat to human settlements, is a major driver of ecological impacts in the Puget Sound region. American Crow (Corvus brachyrhynchos) abundance and use values, as measured by a utilization distribution, responded positively to the amount of land cover providing anthropogenic subsidies at the scale of crow home ranges (18.1 ha) and across study sites (up to 208 ha). The relative concentration of use by crows was highest in grass and shrub cover and 'mixed' land cover (generally a combination of impervious surfaces, grass, and trees) compared to forests. Crows did not respond to forest/nonforest edge, the juxtaposition of particular land cover types, or immediate land cover (within 400 m 2) in predicted ways. Individual crows used different land cover types relatively evenly across their home ranges compared to all crows at a site, reflecting different scales of habitat selection processes.; Increased crow abundance has the potential to affect breeding songbirds via nest predation. At a scale of 1 km2 nest predators and their prey were positively or negatively correlated according to general habitat associations. Within forest patches (1.6 to 18.7 ha), some songbird species appeared to avoid areas of forests with greater predator use. Failed nests had higher predator occurrence (especially of corvids) than successful nests, but relative abundance of nest predators in the landscape was not correlated with nesting success. Reproductive success was generally high, with 52% of all nests and 49% of all territories fledging at least one young (for all species and years combined).; Songbird habitat is one of the many functions that forest patches in urbanizing areas provide. Others include economic and social functions, which were studied across a gradient of urbanization. Housing prices were at a premium in the most- and least urban neighborhoods, compared to suburban areas. Satisfaction with neighborhood attributes decreased with urbanization, while the likelihood of mentioning 'parks' or 'friendly' as an important element of a resident's neighborhood increased. Songbird richness peaked in less-developed areas. Consideration of multiple functions of urban forests simultaneously is important for planners and conservation biologists alike.