A study by scientists at the Central Arizona-Phoenix (CAP) Long Term Ecological Research (LTER) site found that residential yards in urban areas with native vegetation support local bird species better than those with traditional grass lawns, essentially providing "mini refuges".
The study, published in the online journal PLoS ONE, looked at residential landscapes in Phoenix, AZ, and concluded that yards with more natural vegetation seemed more attractive to foraging desert birds, perhaps because they have more food than lush, green urban lawns.
For more information, see Native Plants in Urban Yards Offer Birds ‘Mini Refuges’ or read the original article, Linking Foraging Decisions to Residential Yard Bird Composition.