The best source of information on the population status of American Bittern is the Breeding Bird Survey (BBS). Although American Bittern is a secretive marsh bird, its loud vocalizations make it relatively easy to detect. The northern extent of its range is less well surveyed, but overall coverage by the BBS is high, as is its precision and reliability. The national BBS trend shows a substantial decrease through most of the 1970s and 1980s, and fluctuations around a lower level ever since, with the population currently just more than 50% below early 1970s levels. Declines have occurred in all Canadian Bird Conservation Regions where the BBS has at least medium reliability. The Marsh Monitoring Program only provides data for southern Ontario since 1995 and southern Quebec since 2004. Quebec shows a large decrease, while Ontario shows a moderate increase, in contrast with all other surveys for this species. The moderate increase in Ontario was likely due, at least in part, to increasing Great Lakes water levels, which improve breeding habitat quality for this species in Great Lakes coastal wetlands (Tozer et al., 2024). The continental Christmas Bird Count does not include birds wintering in Mexico, but also shows a large decrease for birds wintering in the United States and Canada.

The goal for American Bittern is to increase the population to the level it was at in the early 1970s, based on the Breeding Bird Survey. Trend data show that American Bittern is currently below its goal range, but it has shown a stable trend over the past decade. Analysis of recent trends and potential growth rates suggests that American Bittern could reach its population goal by 2050 with the support of conservation action.