The vast literature on the history of birds is continually growing, but rarely has this information been compiled so that it is readily available in one reference work. Birds of Ontario is such a work, providing a comprehensive summary of the life history requirements of bird species in the province.

Depletion of fisheries due to acid rain may pose a future threat to bald eagle and osprey populations in some regions. Loss of essential habitat has affected declines in the caracara and western burrowing owl and the disappearance of the norther aplomado falcon from the southern United States. Most populations of the ferruginous hawk, marsh hawk, and prairie falcon appear stable; habitat loss is the most critical factor in population changes.