Table column definitions
 Species
Indicates the species' common English name.
Note on species names:
For some species that have undergone a change in taxonomy since the beginning of the Breeding Bird Survey, trend results are presented for both the individual species as well as a "combined" trend that includes all data for the species complex. Users may wish to examine both. These species complexes are:
 Sapsuckers (Yellowbellied/Rednaped/Redbreasted Sapsucker)
 Traill's Flycatcher (Alder/Willow Flycatcher)
 Western Flycatcher (Pacificslope/Cordilleran Flycatcher): the majority of records in Canada are Pacificslope Flycatchers.
 Solitary Vireo (Cassin's/Blueheaded Vireo)
 Northern Oriole (Bullock's/Baltimore Oriole)
 Blue Grouse (Dusky/Sooty Grouse): in 2006 the species was split into Dusky Grouse and Sooty Grouse. Results are presented only for the Blue Grouse species complex.
 Western Grebe (Western/Clark's Grebe): in 1985 the "Western Grebe" was split into Western and Clark's Grebe. Results are presented only for the species complex; Clarke's Grebe is very rare in Canada and these results primarily reflect the trend for Western Grebe.
 Time Period

Indicates the time period of the estimated trend. Two time periods are reported for each combination of species and region:
 Longterm = first year with sufficient data (usually 1970) to present.
 Shortterm = most recent ten years.
 Annual Trend
 Indicates the trend estimate (i.e., the average annual percent change in the population).
Limits
 Lower
 Indicates the lower 95% credible limit on the estimated annual trend (i.e., conditional on the model and the data, there is a 95% probability that the true trend falls between the lower 95% limit and the upper 95% limit).
 Upper
 Indicates the upper 95% credible limit on the estimated annual trend (i.e., conditional on the model and the data, there is a 95% probability that the true trend falls between the lower 95% limit and the upper 95% limit).
 Overall Reliability
 Indicates categories from low to high. This column combines three specific and largely independent measures of the credibility of the estimated trend. The category reported here is the minimum category of the three primary credibility measures: Geographic coverage, Local data weight, and Precision. See the explanations of each credibility measure for category definitions.
Reliability details
 Geographic Coverage
 Indicates the proportion of the species' regional breeding population within the area covered by the BBS. The reported value is a geometric average annual proportion. In a given year, the area covered is defined as the area within degreeblocks (1 degree longitude by 1 degree latitude) that contain routes contributing data to the analysis. Degree blocks are considered to contain routes contributing to the analysis for all years between the first and last years that routes were run in the degreeblock.
Categories for overall reliability:
 High > 50% regional pop (i.e., > 0.50) within covered area
 Medium 50%  25%
 Low < 25%
Note on missing coverage estimates:
For some species in some regions, no estimate of geographic coverage is provided. These missing values occur when the BBS dataset includes observations of a species from outside the area defined by the species' range map. For strata with no overlap between the observations and the species' range map, the proportion of the species' regional breeding population covered cannot be calculated.
Range maps provide relatively coarse estimates of a species' distribution and can only provide a snapshot in time. BBS observations may, in some cases, track expanding species' ranges, or simply indicate errors in the range maps.
 Local Data Weight
 Indicates the proportion of the region and timeseries for which local data contributed to estimating the local population trajectory. That is, the proportion of the region with some data in each year, averaged across all years included in the trend. A value of 1.0 indicates that there are data from every year and stratum that makes up the region. Values less than 1.0 indicate that some portion of the region (i.e., one or more of the strata included in the region) does not include data from the full range of the time series, and therefore relies on the data from other regions of the species range to estimate those years in the local trajectory.
Categories for overall reliability:
 High = there are local data from > 90 % of the region and years included in the trend.
 Medium = there are local data from ≤ 0.90% and ≥ 75 % of the region and years included in the trend.
 Low = there are local data from < 75% of the region and years included in the trend.
 Precision
 Indicates the width of the 95% credible interval (Upper limit  Lower limit).
Categories for overall reliability:
 High < 3.5 width of credible interval
 Medium 3.5  6.7
 Low > 6.7
These categories indicate trend estimates that are sufficiently precise to confidently identify the following magnitudes of population declines over 20 years:
 High 30% decline
 Medium 50% decline
 Low category includes trends that are too imprecise to confidently identify a 50% population decline over 20 years.
 N Routes
 Indicates the number of unique BBS routes that were included in the analysis and were run at least once between the start and end years of the trend.
 Probability of Decrease
 Indicates the probability that the population has decreased during the specified time period, conditional on the model and the data. For example, a value of 0.944 indicates that there is a 94.4% probability that the population has declined since 1970.
 Probability of Increase
 Indicates the probability that the population has increased between the specified time period, conditional on the model and the data.
 Population Change
 Indicates the estimated percent change in the population size during the specified time period.
 Lower Limit  Population Change
 Indicates the lower 95% credible limit on the estimated percent change in the population (i.e., conditional on the model and the data, there is a 95% probability that the true percent change in the population falls between the lower 95% limit and the upper 95% limit).
 Upper Limit  Population Change
 Indicates the upper 95% credible limit on the estimated percent change in the population (i.e., conditional on the model and the data, there is a 95% probability that the true percent change in the population falls between the lower 95% limit and the upper 95% limit).
 Probabilities of Population Change During Time Period.
 Reflect the probabilities that the total change in population size falls into each of the 6 categories. Values can be added across categories, but may not sum to 1.0 due to rounding errors. All probabilities are estimates, and are conditional on the model and the data (i.e., a different probability might be estimated if a different statistical model and/or observations had been collected from different BBS routes surveyed in different years).
 > 50% Decrease
 Indicates the probability that the population has decreased by more than 50% during the specified time period.
 25%  50% Decrease
 Indicates the probability that the population has decreased by 25 to 50% during the specified time period.
 0%  25% Decrease
 Indicates the probability that the population has decreased by 0 to 25% during the specified time period.
 0%  33% Increase
 Indicates the probability that the population has increased by 0 to 33% during the specified time period.
 33%  100% Increase
 Indicates the probability that the population has increased by 33 to 100% during the specified time period.
 > 100% Increase
 Indicates the probability that the population has increased by more than 100% during the specified time period.