Breeding Bird Survey results

Introduction

This website provides detailed population trend information based on data collected through the North American Breeding Bird Survey (BBS), for over 500 North American bird species. The trend results presented here are for regions of Canada and the continental United States. Trends are presented for species, countries, provinces, territories, states, Bird Conservation Regions, and smaller analysis strata for which there are sufficient BBS data for statistical analysis. These trends and some additional results from the same analysis are also available through the ECCC Data Catalogue.

The BBS is jointly coordinated by Environment and Climate Change Canada and the U.S. Geological Survey (USGS), Eastern Ecological Science Center. Any use of these BBS results for Canada should acknowledge the hundreds of skilled volunteers in Canada who have participated in the BBS over the years and those who have served as provincial or territorial coordinators for the BBS.

Please visit the State of Canada’s Birds web site for a comprehensive assessment of the population and conservation status of most species that breed in Canada, which considers BBS results as well as results from other relevant surveys. For waterfowl, comprehensive assessments are available in the most recent report on the Population Status of Migratory Game Birds in Canada.

New aspects of the analysis in this version

We continually strive to improve the population trend estimates from the BBS.

Changes to the spatial strata used in the 2024 analyses, relative to previous versions. Recently, some of largest Bird Conservation Regions (BCR) in Northern Canada were changed (https://www.birdscanada.org/bird-science/nabci-bird-conservation-regions). These BCRs were subdivided to better reflect the latitudinal and longitudinal variation in bird communities across the Boreal forests. In addition, the boundaries between neighbouring BCRs in Eastern Canada were adjusted to more accurately represent the distributions of birds and their habitats. The spatial strata (smallest regions within-which BBS trends are analysed) are based on an intersection of BCRs with the political jurisdictions (Provinces, Territories, and States), so the changes to the BCR boundaries led to changes in the spatial strata, and therefore the grouping of BBS routes in the analyses and the area weights for each stratum (Figure 1). For example, subdividing the northern BCRs means there are more spatial strata and therefore fewer BBS routes in any given stratum, on average. In addition, some BBS routes are now associated with a different region because of the revised boundaries of BCRs. Finally, because the new BCR definitions have not yet been integrated into the main BBS database (Ziolkowski et al. 2025), BBS routes in this analysis were grouped into strata based on the spatial overlay of the route start locations with the updated BCR*State-Prov-Territory map. As a result, a small number of BBS routes that fall on or very close to the borders of BCRs may have been allocated to a different BCR than in previous analyses. Estimates for most species and regions are almost identical to previous versions. However, because of these revised BCRs and new spatial strata, estimates of population trends and the long-term population trajectories may have changed for a small number of species.

Note on the Bird Conservation Region numbers and codes. The new BCR formed by the subdivision of the large northern BCRs were given interim alpha-numeric codes when the boundaries were first defined, which were the codes used in these analyses. These interim alphanumeric codes were subsequently changed to numeric codes, which will be used in future analyses, and will be found on published maps. The alphanumeric codes correspond to the new numeric codes as follows: (3C = 68, 3N = 69, 3S = 70, 6N = 71, 6S = 72, 7W = 73, 7H = 74, 7E = 75, 8W = 76, 8E = 77). The English and French names of the BCRs remain the same as those used in the current analyses and can also be used to locate BCRs on the maps.

These estimates were produced using a new spatially explicit statistical model that tracks changes in populations through time with a non-linear smoothing function and year effects (Generalized Additive Model with Year Effects, "GAMYE"). This model was developed to better track non-linear changes in species populations, such as population cycles due to natural climatic processes or change points where populations begin to decline or to recover from earlier declines. The spatially explicit components were developed to improve estimates of population change in each region by sharing information on trends in neighbouring regions. This local sharing of information improves both the local estimates and the overall estimates of change. A full description of the GAMYE model and the spatially explicit versions is freely available in two articles published in the journal Ornithological Applications (Smith and Edwards, 2021), and Smith et al. 2024).

For each species, the same spatial regions of the country are included in both short-and long-term population trends. In previous versions of these estimates, some regions were excluded from the long-term trends if there were no local data in the early portion of the time series. The new model includes parameters that allow the population trajectory from regions with data missing from some portion of the time series to be estimated based on information from other regions of the species’ range, and so it is no longer necessary to remove these regions from the calculation of long-term trends. We have redefined the reliability metric “local data weight” to identify regions where the data may be missing from the early portion of the time series and to indicate the relative importance of these missing data.

Finally, the maps that show the spatial regions included in each trend estimate are now coloured to also show the population trend in each region. Cool colours(blues) indicate increasing trends and warm colours(reds) indicate decreasing trends.

Visit the BBS statistical methods page for more information on the statistical methods used to produce these trends, annual indices and credibility measures.

View trends and annual indices

• View Breeding Bird Survey trends by selecting a species
• View Breeding Bird Survey trends by selecting a geographical region

Please send enquiries about the Breeding Bird Survey in Canada to: bbs@ec.gc.ca

This web site may be cited as: Smith, A.C., Hudson, M-A., English, W.B., and Francis, C.M. 2026. North American Breeding Bird Survey - Canadian Trends Website, Version 2024. Environment and Climate Change Canada, Gatineau, Quebec, K1A 0H3

Note: the interim alphanumeric codes used here for Bird Conservation Regions 3S, 6N, 6S, 7W, 7H, 7E, 8W and 8E have been replaced by numeric codes (70 through 77 respectively) in the most recent update to the BCRs. The English and French names of the BCRs are the same

Any use of these BBS results for Canada should acknowledge the hundreds of skilled volunteers in Canada who have participated in the BBS over the years and those who have served as provincial or territorial coordinators for the BBS.

1. Smith, A. C., & Edwards, B. P. M. (2021). North American Breeding Bird Survey status and trend estimates to inform a wide range of conservation needs, using a flexible Bayesian hierarchical generalized additive model. The Condor, duaa065. https://doi.org/10.1093/ornithapp/duaa065
2. Smith, A. C., A. D. Binley, L. Daly, B. P. M. Edwards, D. Ethier, B. Frei, D. Iles, T. D. Meehan, N. L. Michel, and P. A. Smith. (2024). Spatially explicit Bayesian hierarchical models improve estimates of avian population status and trends. Ornithological Applications 126:duad056. https://doi.org/10.1093/ornithapp/duad056.