Large-scale and long-term population monitoring programs are an essential element in bird conservation. We use the information provided by these programs to determine how species’ population statuses changes over time, and to highlight those in need of conservation action. We also use monitoring results to measure the impact of management actions and, in some cases, to help identify the causes of population change. The species accounts presented here highlight how we can use these monitoring programs to establish baseline population levels, and to identify important changes in bird populations over the past 47 years.
The focus of this website is to use the best available results from bird monitoring programs to assess the current (1970-2016) national population status of each species. This version of the website also includes species-specific national population goals. We present these goals as targets for conservation, and as reference points with which to measure the success of conservation actions.
This version of the website includes all bird species that breed or regularly occur in Canada, including some at the subspecies/population level. You can view earlier iterations (1970-2010, 1970-2011, and 1970-2014) in the website archives (see "Versions" on left hand menu). Over the long-term, these different website versions will help track how well we monitor birds in Canada, and how we are improving. As we accumulate more monitoring data and improve our analytical methods, the reliability of the population assessments presented here should increase, and we should consider fewer species to be data deficient. In all versions, we assess the population status for each species relative to circa 1970 (i.e., early 1970s), or as close as data allow. We selected this period as the reference point both because there are few data prior to this period for most species, and because it is feasible to base conservation objectives on population levels at that time. However, 1970 may not be an appropriate reference point for all species. For example, some raptors and other birds experienced dramatic declines in the 1950s and 1960s due to DDT, and were at very low levels in 1970. We took this into consideration when establishing population goals for these species.
To determine a species’ population status, we examined all available monitoring program results for each species, and used the most reliable source(s) for assessing the long-term, national status. For most landbirds, we used the Canadian results from the North American Breeding Bird Survey (BBS) (Smith et al. 2019). If the BBS does not adequately cover the species, we used other sources instead of, or to supplement the survey. For example, some birds breed in northern Canada, beyond the region covered by the BBS, and spend their winters in the United States and more southern parts of Canada, where we can monitor their populations with the Christmas Bird Count (CBC). We used CBC results to assess many of these northern landbird species and to supplement the information available for other species. We also used results from other sources, such as provincial breeding bird atlases and species-specific surveys. For other species’ groups, we used aerial waterfowl surveys, shorebirds migration surveys, seabird colony monitoring programs, coastal water bird counts, marsh monitoring programs, and a variety of species-specific surveys.
We present a variety of species’ designations, including:
These designations differ in scale, scope, and timing, leading to possible differences among designations for any given species. For example, the IUCN Red List identifies wildlife species threatened with extinction on a global scale, whereas COSEWIC evaluates the risk of extinction for wildlife species in Canada. COSEWIC and IUCN only assess or re-assess a small portion of species in any given year. Assessments for the Wild Species report are conducted every 5 years and provide a coarse-scale summary of the status of species in Canada, which allows species to be prioritized in terms of the effort and attention needed to prevent their further decline or loss, or indicates when more information is needed. In Wild Species, the definition for "Secure" includes all species that are not thought to belong in the "At Risk" or "Sensitive" categories. The "Secure" category can include species that show a decline in Canada but remain relatively widespread or abundant. Note also, that Wild Species designations are always made at the species level, while COSEWIC may treat subspecies, varieties, or populations separately. COSEWIC may also designate species for reasons other than population decreases (e.g., small population size, degree of threats).
We see an example of different designations in the Blackpoll Warbler account. The Blackpoll Warbler is listed as Near Threatened at the global level (Red List 2018), and is on PIF’s Common Birds in Steep Decline List (PIF 2017). It is also considered a "Priority" species in four of NABCI’s Bird Conservation Strategies. However, COSEWIC has not assessed the species, nor has it identified it as a potential candidate species for assessment. It is currently considered "Secure" in Canada according to Wild Species 2015. Here, we assessed the Blackpoll Warbler as being data deficient, given the lack of coverage of the species’ range in Canada.
For all species except waterfowl, we based our methods for determining the population status of each species and its reliability, with some modifications, on those developed by Blancher et al. (2009) to assess the population trend status of forest birds in Ontario. Most accounts were written in 2010 by a variety of experts and reviewed by an editor; each of these accounts has subsequently been revised and updated for each version of the website. To improve consistency among authors and editors, we provided written guidelines (described below). Once updated, each account underwent a detailed peer review by one or more Environment and Climate Change Canada (ECCC) bird experts.
Because we hunt and therefore carefully manage most waterfowl species, we based the waterfowl accounts on ECCC’s 2017 Population Status of Migratory Game Birds in Canada report. Detailed methods can be found in that report (Canadian Wildlife Service Waterfowl Committee 2017).
We assessed all available trend and annual index results to select the most appropriate source(s) (see Table 1, though note that only large-scale surveys are included in this table) to determine the change in the species’ national population status relative to 1970. Most surveys are based on abundance data but there are some exceptions (e.g., trends from the Atlas of the Breeding Birds of Ontario are based on detection/non-detection in atlas squares). We also investigated and used other sources of data, if appropriate (e.g., Canadian Migration Monitoring Network trends, species-specific surveys or accounts from provincial breeding bird atlases, and sources in the published literature).
We assessed the reliability and accuracy of each survey to determine a) if we should consider results from a particular survey at all, and b) which survey was the most appropriate if there was more than one source of information available. Where possible, we considered three measures of reliability for each survey: precision of the trend, coverage of the species’ breeding population or range, and survey design. We used precision of the trend estimate to determine whether the available data could reliably detect biologically significant population trends. We used a coverage analysis to determine the proportion of a species’ breeding population or range covered by the survey. We examined the survey design for strengths, weaknesses, and potential biases for each species. We provide a more detailed description of this process in the following sections.
For surveys analysed using a Hierarchical Bayesian model (e.g., BBS, CBC, Shorebird Migration Monitoring, and Seabird Colonial Monitoring Program) precision reflects the width of the 95% credible interval (upper limit - lower limit). For more details on the BBS analysis, see Smith et al. (2019). For more details on the CBC analysis, see Soykan et al. (2016). The 95% credible interval defines a range of trend values that have a 95% probability of including the true population trend value. We used similar categories for surveys analysed by other means based on the width of the confidence interval (e.g., Great Lakes Marsh Monitoring Program, Nocturnal Owl Monitoring Program). We then assigned the credible interval/confidence interval to 3 categories of precision:
These categories indicate trend estimates that are sufficiently precise to confidently identify the following magnitudes of population declines over 20 years:
For the Atlas of the Breeding Birds of Ontario, we derived a working standard error from the upper and lower bounds on the slope as follows: we converted the bounds to the natural log scale and used the difference between the upper and lower bounds divided by 4 as the working standard error. For some species, the lower bound for the slope from the Ontario Atlas was 0.0. In these cases, we used the reported slope instead of the lower bound and the resulting difference was divided by 2.
Precision estimates were not available for some surveys, such as the Great Lakes Decadal Colonial Waterbird Census, species-specific surveys and, in some cases, information from published literature.
We obtained estimates of the proportion of a species’ breeding population or the species’ range covered by a survey, whenever possible. Where these were not available, we estimated coverage for surveys based on a coarse assessment of the species’ range and the survey coverage area.
For the BBS, coverage represents the proportion of the species’ breeding population within the area covered by the BBS. The reported value is a geometric average of the annual estimates. In a given year, the area covered is defined as the area within degree-blocks (1 degree longitude by 1 degree latitude) that contain routes contributing data to the analysis (Smith et al. 2019).
We assigned the reliability of survey coverage to 3 categories (based on Blancher et al. 2009):
For a given species, we assessed the characteristics of a survey that have the potential to introduce bias to estimates of population trends. This assessment indicates a risk of bias and not the actual presence of bias in the estimates. That is, a score of low reliability only indicates that bias in the trends is possible -- it does not indicate that the estimates are inaccurate. We assigned this criterion to 3 categories (based on Blancher et al. 2009):
For example, we considered results from the CBC to be less reliable if they were based partially on birds that may have spent the breeding season outside of Canada (e.g., continental trends for species that breed in both Canada and the United States). We also considered the factors outlined in Sokyan et al. (2016) that were associated with differences in population trends between the BBS and CBC (e.g., species counted on fewer than 300 CBC circles, and those small winter ranges [< 2.5 million km2]). Also, for some species, especially common species, the change in the probability of observation from the atlases have been found to underestimate the magnitude of population change relative to other surveys that are based on abundance data (Blancher et al. 2009).
This assessment does not address sources of bias that may affect other estimates from a given survey. For example, estimates of absolute abundance or abundance relative to other species derived from the BBS may be biased if a given species avoids or is attracted to roadsides. However, roadside attraction or avoidance behaviour will not bias BBS trend estimates unless this behaviour has changed over time.
The reliability rating given to each survey usually equaled the minimum rating of the above 3 reliability measures, with some exceptions. If results were based on very low sample sizes, they were generally not rated as being high reliability unless the species only exists at those few sites. In some cases, we downgraded survey reliability if the trajectory of the annual index was strongly non-linear, showed a strongly cyclic population, or if the trend figure was strongly influenced by an idiosyncratic year(s) in the population trajectory of the annual indices. We might also have downgraded a survey’s reliability if there were substantially less than 40 years of data, which would lead to uncertainty about the species’ population status relative to 1970. We upgraded survey reliability if the trend result was highly significant and the magnitude of the trend was very large, even if other factors were low. For example, BBS results for the Wild Turkey have low precision but the magnitude of the annual trend (14.5%) leaves little doubt that an increase in the Wild Turkey population has occurred.
Based on the reliability assessment (described above), we selected the most reliable, long-term survey as the primary source to use in determining the species’ national population status relative to 1970. We considered the use of only one source sufficient if the results of that survey were highly reliable. However, authors could also consider results from other surveys (secondary survey) if two highly reliable sources were available. When the primary survey reliability was medium or low, we used an additional data source (secondary source, if available) to increase the assessment’s validity. We used a third source (tertiary survey) if the reliability of all other sources was low to provide corroboration, or if the third source demonstrated a different point (e.g., a regional population trend that differed significantly from the national trend). If available, we sometimes used a third source to help corroborate the status in cases where the primary and secondary had similar reliability ratings but different results, in either direction or magnitude. We always preferred survey results based on Canadian data. However, for a few nomadic species for which the majority of the population is in the United States, we used results at the North American scale to reflect the population status in Canada. In these cases, we usually lowered the reliability of the population status.
If we only used one survey, the trend result for that survey equaled the final population status. If we used more than one survey, we weighted the surveys according to their reliability, and integrated the results to assign a population status category. The results from the most reliable survey(s) that had data going back to about 1970 carried the most weight. If the most reliable trend information did not date back to about 1970, we used the most reliable results with the longest time series, along with any other information that suggested change since about 1970 (e.g., results from less reliable sources of information on habitat availability or threats operating at that time). We used both trends and annual indices, if available. If both the trajectory of the annual index and the trend of the survey closely agreed, we used the trend to determine the population status. However, if the trajectory was non-linear, we used our judgment when weighing these sources of information.
On the website, we present both long-term and short-term national trends, as well as annual indices (if available). Although the focus of the assessment is on the long-term status (i.e. current vs. 1970), recent changes in population are also of interest because they can help indicate whether the rate of population change is continuing, increasing, stabilizing, or reversing. A recent steep decline for a species that has been stable over the long-term could be of significant biological concern, whereas a recent decline in a fluctuating (cyclic or irruptive) species might be expected and would be of less concern. Regional results are displayed for some species, usually only in areas where the species’ distribution is most concentrated, and/or if the regional results are reliable enough to indicate that the population change is different in a portion of the species’ range and if that difference has implications for conservation.
Population status categories are:
These categories are purposely asymmetrical. Values of population change on a percent-scale are not symmetrical around zero because a population can increase far beyond 100%, but can never decrease past 100% because a 100% decrease represents extinction. The Large and Moderate change category definitions reflect the opposite changes required to return to the earlier level. For example, a large increase is required to recover from a large decrease, and vice versa; a population that has declined by 50% must then increase by 100% to return to its original level.
We based the overall reliability of the population status relative to about 1970 on an integration of individual reliabilities from the selected surveys. If we only used one survey to determine the population status, the overall reliability was equal to the reliability for that survey. If we used more than one survey to assign status, we considered a lower value for the overall reliability if there was substantial disagreement in trend among the surveys used, or a higher value if multiple surveys all pointed to the same population status. The overall reliability category generally matched the following definitions (based on Blancher et al. 2009):
In 2012, ECCC established a specific, quantitative population goal for most native bird species in Canada. However, recognizing that bird populations vary naturally over time and some deviation around the goal is to be expected, we also defined minimum and, when relevant, maximum levels of acceptable variation. We assessed the current population status of each species with respect to these goals to create a flagging system for species of possible conservation concern. Under this system, species falling within acceptable variation would not trigger immediate conservation concerns because they are reasonably close to their goals. Species falling below or above their limits would be flagged either as possible species at risk or those that may require population management.
Here, we briefly explain the framework for establishing both the goals and the upper and lower limits (see Population Goals Framework PDF). We applied this framework to all species, though we based a few exceptions on expert advice from members of ECCC’s bird technical committees.
We attempted to set goals for approximately 530 species or management-populations (hereafter referred to as "species" for simplicity; some species, mostly harvested species, are managed within distinct sub-populations). For approximately 80 species, we were unable to set a goal because no long-term monitoring information was available. For harvested species and for Species At Risk, we used existing quantitative goals when available (e.g., from the North American Waterfowl Management Plan or from Species At Risk Recovery Strategies). For all other species, and for Species At Risk and harvested species for which an existing quantitative goal was not available, we set the population goal according to the process described below.
Our framework followed a hierarchical process that considered the species’ current and historical distribution, population size, and abundance. We set species’ population goals relative to either the species’ population in approximately 1970 (i.e. the first five years of most standardized monitoring programs, usually 1970-1974, hereafter "1970 population levels"), or the species’ population in approximately 2012 (i.e., the mean of the species’ estimated abundance in 2008-2012, hereafter "2012 population levels"). In most cases, we set goals based on a species’ population trajectory; those that have increased since 1970 were set at 2012 population levels, and goals for species’ populations that have decreased or shown little overall change since 1970 were set at 1970 population levels.
In addition to the goals themselves, we also set a lower level of acceptable limit relative to each goal based on the observed variation in abundance of each species. These lower levels acknowledge that the baseline dates (i.e. 1970, 2012) used are somewhat arbitrary, that populations fluctuate naturally, and that there is uncertainty around even our best estimate of a species’ abundance in any given year. In most cases, we set the lower limit to one of three options based on the population’s overall trend and inter-annual variation: 1) for most stable or increasing species with high inter-annual variation, the lower level is the 10th percentile of the observed annual levels of relative abundance between 1970 and 2012 (i.e. abundance below which 10% of the estimates are found); 2) for most decreasing species, the lower level is 75% of the goal; and 3) for most increasing species, the lower level is 75% of the long-term mean of the observed annual levels of relative abundance.
Though we focused on a species’ population and its trajectory, we also considered each species’ current distribution within Canada, its size relative to the species’ historical distribution, and the species’ distribution outside of Canada (e.g., goals and/or lower limits were generally lower for species with very restricted Canadian distributions and for species with distributions that have greatly expanded since approximately 1970). For species whose distribution has either decreased or remained the same as historical levels (i.e. early- to mid-20th century or before), we set the goal at 2012 population levels if the species’ abundance had increased more than 25% since 1970, and at 1970 population levels for species whose populations have either decreased or changed little since 1970. We also considered whether the species’ 2012 and/or 1970 population levels met societal and ecological needs. For example, for those species that have increased steadily since 1970, we set the lower limit assuming that no conservation action is likely required unless the population drops below those lower levels observed in the 1970s. However, for many raptors (see Farmer et al. 2008) and other species that are currently increasing but were at unnaturally low levels in the 1970s due to the effects of DDT, direct persecution, or other human-related factors, no goal was established but a lower limit was set to 2012 population levels or the 95% percentile of observed abundance (1970-2012); we assumed that any subsequent decrease would be cause for renewed conservation action. For species whose abundance or distribution is greater than historical levels, we set the goal at 1970 population levels, unless that level was high enough to cause human or ecological conflicts. For the few species considered to cause human or ecological conflicts, we set an upper acceptable level of variation from the goal.
Status in relation to national population goal categories are:
This page, which is available by selecting "Click here for more details" under the Population status header in each species’ account, provides:
For most species, a table of selected survey trends and, if available, graphs of annual indices are also shown.
Population trends table: This table displays the annual percent change in population for the longest period of each selected survey and, when available, the most recent period. The geographic area, and range of years included in the trend, and upper and lower credible/confidence intervals are displayed.
Annual index graphs: For the BBS, CBC, and shorebird migration surveys, annual index graphs show an estimate of the average number of individual birds that would be seen on a randomly selected route/count by an average observer under average conditions. For the seabird colony monitoring program, annual index graphs reflect the estimated sum of all birds nesting at monitored colonies.
We selected the most appropriate maps to display for each species. These included species distribution, relative abundance, regional breeding evidence, and migration movement maps (e.g., Nature Serve range maps, BBS relative abundance maps, eBird sightings maps, and maps from the various provincial breeding bird atlases). NatureServe maps are displayed for all species unless an alternative map was more appropriate. Where preferable, range maps from Birds of North America Online (2015) or Sibley (used with permission of David Sibley) were used instead of NatureServe. We displayed BBS relative abundance maps for most species whose ranges are relatively well covered by BBS. We displayed maps from the provincial breeding bird atlases for species whose distributions are concentrated in one or two provinces. View additional information on each map by selecting the map title in each species’ account.
We sourced population estimates for the various species groups and placed them into broad categories, which were then reviewed by ECCC’s Bird Technical Committees.
Landbirds: We extracted the majority of landbird population estimates from the 2019 Partners in Flight (PIF) Population Assessment Database (PIFa 2019), and the Avian Conservation and Assessment Database (PIFb 2019), which were generated by the PIF Species Assessment Process and were companions to PIF’s Landbird Conservation Plan (Rosenberg et al. 2016) and the State of North America’s Birds report (NABCI 2016). These reports provide a continental synthesis of priorities and objectives to help guide landbird conservation actions at national and international scales. View the complete Species Assessment Database for more information. We sourced a small number of population estimates from species at risk assessments, expert opinion, and other documentation.
Shorebirds: ECCC experts derived population size estimates based on Andres et al. (2012), and updated these estimates with published or unpublished information where available. For each species, the estimates include all populations breeding within Canada, as well as numbers estimated to pass through Canada on migration if the breeding grounds lie outside Canada, i.e., the total number of that species estimated to use Canada. For breeding populations, these continental estimates were then converted to population estimates for Canada using relative abundances estimates when available, estimated proportion of the range in Canada or expert opinion.
Seabirds and Waterbirds: ECCC staff derived population estimates of regional seabird populations in 2018 using published and unpublished information. These regional estimates were summed to determine the population estimate for Canada. For colonial-nesting species, population estimates were derived from colony counts of nests or breeding pairs conducted during the nesting season. For other waterbirds, we derived population estimates from information obtained through dedicated monitoring protocols (e.g., acoustic sampling for elusive marsh birds and counts at migratory staging areas). ECCC’s Waterbird Technical Committee reviewed the final estimates.
Waterfowl: We extracted waterfowl population estimates from the 2017 Population Status of Migratory Game Birds in Canada report (Canadian Wildlife Service Waterfowl Committee 2017) whenever possible. These estimates were obtained during waterfowl aerial surveys conducted mostly during the breeding season and on the staging and wintering areas. We extracted global population estimates from the 2018 North American Waterfowl Management Plan (NAWMP Committee 2018).
We assigned all species to a category based on their migration strategy and/or occurrence in Canada. For landbirds, we assigned migration strategy/occurrence categories largely according to Peterjohn and Sauer (1993). For a few landbirds not classified by Peterjohn and Sauer (1993), we added designations based on WildSpace (Wong et al. 2003). ECCC’s Landbird Technical Committee then reviewed and revised them as appropriate. We based migration/occurrence categories for shorebirds and waterbirds on WildSpace (Wong et al. 2003), with revisions made by ECCC experts as needed. ECCC staff provided migration/occurrence categories for waterfowl. In some cases, it was difficult to assign a species to a single migration strategy; we did not categorize these species. Migration/occurrence categories are:
We present Canadian responsibility scores for each species. We based the scores on the percent of the world population of the species estimated to be in Canada, using the ratio of Canadian population estimates to range-wide estimates. For landbirds, we extracted Canadian and world population estimates from the 2019 Partners in Flight (PIF) Population Assessment Database (PIFa 2019 and PIFb 2019). For the few species without population estimates for Canada, we used the percent of the global breeding range in Canada, based on NatureServe digital range maps for the Western Hemisphere (Ridgely et al. 2007), PIF estimates of proportion of range outside of the Western Hemisphere (Blancher et al. 2007), quantitative criteria from COSEWIC, or expert opinion. For shorebirds, we extracted global population estimates from WPE5 (Wetlands International 2012), Andres et al. (2012), or the 2019 PIF Population Assessment Database (PIFb 2019) when appropriate, and Canadian population sizes were estimated based on the proportion of the range within Canada (Natureserve; Ridgely et al. 2007), or relative abundance data, when available. For waterfowl, we extracted Canadian estimates from the 2017 Population Status of Migratory Game Birds in Canada report (Canadian Wildlife Service Waterfowl Committee 2017), and obtained global population estimates from the 2018 North American Waterfowl Management Plan (NAWMP Committee 2018). If estimates were not available for Canada, responsibility score were based on range maps or minimal population estimates. For seabirds, we derived the ratio of Canadian population estimates to range-wide estimates from the following sources: for loons, gulls, terns and cormorants, Delany and Scott (2006); for auks, Gaston and Jones (1998); for petrels, Brooke (2004); for Northern Gannets, BirdLife (2014); and for Pelagic Cormorant, because Delany and Scott (2006) provide only an estimate for North America, Hobson (2013). Note that some species are subject to taxonomic uncertainty and estimates of Canadian responsibility could be different if a different taxonomy were to be adopted. We sourced world population estimates for waterbirds mainly from Milko et al. (2003), as well as from the 2019 Partners in Flight (PIF) Population Assessment Database (PIFb 2019) when appropriate. ECCC experts reviewed the Canadian responsibility scores for each species and adjusted when necessary.
Categories used for Canadian responsibility scores are:
