The best source of information on the population status of Black-billed Cuckoo is the Breeding Bird Survey (BBS). Although some calls be mistaken for Yellow-billed Cuckoo in the restricted region where the two species overlap in range, the BBS provides good coverage and high precision, resulting in at least medium reliability. BBS data indicate a moderate, long-term gradual decrease in abundance since the early 1970s. The population is currently 48% lower than in the 1970s. Declines have occurred in all Canadian Bird Conservation Regions where BBS reliability is at least medium. On the contrary, the second Quebec Breeding Bird Atlas (2010-2014) showed no apparent change relative to the first (1984-1989), while the second Ontario Breeding Bird Atlas (2001-2005) indicated an apparent increase compared to the first (1981-1985), Results from the third Ontario atlas (2021-2025) will provide additional insight into more recent trends.

The goal for Black-billed Cuckoo 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-billed Cuckoo is currently below its goal range, but it has shown an increase over the past decade. Analysis of recent trends and potential growth rates suggests that Black-billed Cuckoo could reach its population goal by 2050 with the support of conservation action.