Synthesizing trends from multiple sources to assess The State of Canada’s Birds

Multiple monitoring programs provide data on the distribution, abundance, and/or population trends of birds in Canada. These programs vary in design, scale, target species, timing, and objectives, which may include status assessment, evaluating specific management actions, or public engagement. To maximize the value of these disparate sources for conservation, the information they provide must be synthesized in ways that account for this variation. We present an approach to bring together trends from multiple sources to assess the national population status of birds in Canada for both individual species and species groups. We assessed the reliability of all available trend sources for a given species based on their geographic coverage, suitability for the species, and precision of resultant trend estimates. We then used the most reliable sources to describe long-term population trends, set quantitative conservation goals, and assess the current population status relative to those goals. We found that a few multi-species surveys provided the best information for most species, but targeted surveys were essential for species that are rare or difficult to detect in multi-species surveys. Despite birds being among the best monitored taxa, we only had high or very high confidence in 35% of species status assessments. We also developed an approach to synthesize trends across species with shared taxonomy or life history traits to identify potential conservation challenges or successes. Among the groups we analyzed, waterfowl and birds of prey had large increases on average since 1970, while grassland birds, aerial insectivores, and shorebirds experienced large declines. To make the results widely available to support conservation efforts, we developed a user-friendly web platform, The State of Canada’s Birds, to present the resultant assessments and underlying data for the 463 species that regularly occur in Canada, together with aggregated trends of selected species groups. Our analytic approaches could be useful for assessing population trends for any geographic area or taxonomic group with multiple information sources. Enabling and maximizing the use of existing data, as well as making data and the interpreted products derived from those data more available, are foundational steps in addressing the biodiversity crisis.