This is from the Cornell Lab of Ornithology, please read more at the link above.
Besides the lack of suitable habitat for birds, urban areas present unique threats to birds, such as window strikes and pet cats. According to the American Bird Conservancy, cats may kill hundreds of millions of birds, small mammals, reptiles, and amphibians each year. However, little is known about which bird species are affected most, or about the extent to which people can influence the level of cat predation in their yard. Tessa Murante completed her undergraduate honors thesis in May 2007, working with our research team at the Cornell Lab of Ornithology to analyze data from My Yard Counts. She found a surprising diversity of bird species killed by cats in residential areas (Figure 1 below).