The U.S. Fish and Wildlife Service has a webpage devoted to migratory bird conservation info and data. The Migratory Bird Data Center page is here.
By accessing various databases at this site, I was for example able to learn that 69,840 federal duck stamps were purchased in Wisconsin in a recent year (2003 was the year I chose).
I was also able to easily access links to bird abundance maps. To choose one for the Boreal Chickadee, for example, I went to this link - which helps me to understand why we see so few of them in Wisconsin. Most of their range is north of us. To see the entire list of links to abundance maps, go here.