The Cooper's hawk population here in the Twin Cities has been growing over the past 10 years or so. Last year they were the species that was emitted the most into the clinic at The Raptor Center. The most accepted theory about their increase in population is the increase of people feeding birds at feeders. Bird feeders are like a buffet for the Cooper's Hawk. This food source is especially important during the winter. Most birds do not migrate because of cold. They migrate because of a lack of food during the cold winter. As there are more bird feeders out, there is more food available during the winter. So more song birds stick around instead of heading south. The more song birds that stick around over the winter the more food available to the Cooper's hawk. So more Coops hang around during the winter instead of heading south.