The best source of information on the population status of Black-crowned Night Heron is the Breeding Bird Survey (BBS). Although the crepuscular to nocturnal activity and colonial breeding of Black-crowned Night Heron are not ideally suited to the BBS, overall reliability is considered medium based on its coverage and precision. BBS data indicate a large long-term decrease in abundance since the early 1970s, with the steepest declines occurring during the 1980s and 1990s, and the population currently just over 70% lower than in the early 1970s. At the regional level, reasonably reliably results are available only for the Prairies and for southern Ontario and Quebec, which both show large long-term declines of nearly 60%. The Great Lakes Decadal Colonial Waterbird Census suggests that the population in this region has changed little relative to 1970 (~2,000 breeders in the mid-1970s to ~1,800 breeders in 2024).

The goal for Black-crowned Night Heron 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 Black-crowned Night Heron is currently below its goal range, but has shown a relatively stable trend over the past decade. Analysis considering the historical population loss and recent trend suggests that it is unlikely that the goal can be met by 2050, so the interim target is to reach 60% of the goal by 2050. Achieving this target, and ultimately reaching the national goal for this species, will require deliberate conservation action.