While we may speak historically and metaphorically of canaries in coalmines, in actuality, all bird species speak to the health of their ecosystems, remaining an early warning system. The State of Birds Report has continued to document declines in bird populations during its 40 years of reportage. The current 2009 report lists particular species at greatest risk and suggestions for remediation within respective ecosystems.
For more information about bird species, do consult the online edition of Birds of North America. This comprehensive reference tool details the life histories of more than 716 North American species. The online edition, a product of the Cornell Lab of Ornithology, supplies descriptive text, image collections, audio and video to illuminate aspects of behavior and habitat.