Secretive and well-camouflaged, the American Bittern is ideally monitored through call-playback methods such as those used in the Great Lakes and the Quebec Marsh Monitoring Programs. However, limited geographic and temporal coverage of both of these surveys means that results from the Breeding Bird Survey (BBS) are a more reliable source of long-term national trends. With its distinct vocalizations, the American Bittern is likely better sampled by the BBS than other elusive marshbirds. BBS results demonstrate that the abundance of American Bitterns has fluctuated over the years, including an important decrease in the 1970s and more recent increases (see Canada graph below). Regional results vary for this widely distributed species (results for the various Bird Conservation Regions that host the species and for which there are reasonably reliable results are shown below). Supporting information from the Great Lakes and Quebec Marsh Bird Monitoring Programs also suggest a stable population in more recent years in those areas. Overall, the species appears to have experienced a small decrease in the national population since 1970, but the magnitude of that decrease remains within the category considered to be of "little change". BBS results from througout North America indicate a loss of almost 42% of the continental population since 1970. Though the American Bittern is currently at an acceptable level relative to its national population goal, it has dipped below in the past and may do so again (see Canada graph below).
Additional information on: Breeding Bird Survey (BBS) - Canadian analysis
Additional information on: Great Lakes Marsh Monitoring Program
Additional information on: Quebec Marsh Monitoring Program
