Birders

I live in Denver proper and since I have been in my house (2014) we have seen an increase in species richness and abundance at my house. Broad-tailed hummers and Spotted towhee are now regulars, when they weren't here when we moved in. We also have had Cooper's hawks here for the last few years. I attribute this to a few factors.
1. Less feral cats as we get coyote and foxes in the neighborhood now. Also, people generally keep their cats indoors here.
2. Regular water and food. As surrounding areas become drier, urban vegetation and water sources are more dependable. We have many flowers and feeders.
3. Liberal neighborhood with many houses not using pesticides, increasing insect abundance.

I realize urban areas won't help many species that are habitat specialists and this is just one sample of a neighborhood over a limited number of years.