Frontispiece. Chandler S. Robbins counting birds at a North American Breeding Bird Survey stop, ca. 1985. Photograph by Barbara A. Dowell.

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 1 Monograph The North American Breeding Bird Survey 1966–2011: Summary Analysis and Species Accounts

John R. Sauer*, William A. Link, Jane E. Fallon, Keith L. Pardieck, David J. Ziolkowski Jr. United States Geological Survey, Patuxent Wildlife Research Center, 12100 Beech Forest Road, Laurel, Maryland 20770

Abstract

The North American Breeding Bird Survey is a roadside, count-based survey conducted by volunteer observers. Begun in 1966, it now is a primary source of information on spatial and temporal patterns of population change for North American birds. We analyze population change for states, provinces, Bird Conservation Regions, and the entire survey within the contiguous United States and southern Canada for 426 species using a hierarchical log-linear model that controls for observer effects in counting. We also map relative abundance and population change for each species using a spatial smoothing of data at the scale of survey routes. We present results in accounts that describe major breeding habitats, migratory status, conservation status, and population trends for each species at several geographic scales. We also present composite results for groups of species categorized by habitats and migratory status. The survey varies greatly among species in percentage of species’ range covered and precision of results, but consistent patterns of decline occur among eastern forest, grassland, and aridland obligate birds while generalist bird species are increasing.

Keywords: hierarchical models; population survey; species groups Received: October 27, 2011; Accepted: July 12, 2013; Published Online Early: August 2013; Published: December 2013 Citation: Sauer JR, Link WA, Fallon JE, Pardieck KL, Ziolkowski DJ Jr. 2013. The North American Breeding Bird Survey 1966-2011: Summary Analysis and Species Accounts. North American Fauna 79: 1–32. doi:10.3996/nafa.79.0001 Copyright: All material appearing in North American Fauna is in the public domain and may be reproduced or copied without permission unless specifically noted with the copyright symbol ß. Citation of the source, as given above, is requested. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service. * Corresponding author: [email protected] Subject Editor: Colleen Handel, United States Geological Survey, Anchorage, Alaska

Introduction United States, Canada, and Mexico. From their efforts, comprehensive summaries of population The North American Breeding Bird Survey (BBS) change have been calculated for .400 species of is a unique collaborative effort to increase our birds (Sauer et al. 2003). For most of these species, understanding of North American bird populations. the BBS forms the only source of information on the Started at a time when concern about bird popu- dynamics of the populations. BBS observers must be lations was focused on effects of pesticides, the BBS able to identify birds by sound and sight, and the now serves as the primary data source for estimating population changes of North American birds and for attention placed on competence of observers (at modeling the possible consequences of changes in first informally, and more recently through online land use, climate, and many other possible stressors training programs) greatly increased the rigor of the on bird populations. Jointly coordinated by the information, paving the way for additional bird United States Geological Survey, the Canadian survey programs that rely on volunteer observers. Wildlife Service, and, since 2008, the Mexican Although it has limitations, no other survey comes National Commission for the Knowledge and Use close in combining public participation and scientific of Biodiversity, the BBS incorporates the efforts of rigor to provide information for bird conservation thousands of volunteer bird counters across the and natural history.

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This summary of BBS results presents a synthesis implemented a pilot effort in Maryland and of information on bird population change and Delaware in 1965 and then inaugurated the survey distribution. We integrate habitat and migration in the eastern United States in 1966. Canadian status information, distribution maps depicting collaborators, particularly Anthony Erskine, imple- relative abundance, and current estimates and mented the survey in southeastern Canada in 1966 graphical illustrations of population change into as well. Survey routes were established in the central accounts for 426 species of North American birds. United States in 1967, and by 1968 the sampling The accounts provide a concise description of both framework had grown to include the continental the present efficiency of the survey, in terms of United States and much of southern Canada. precision of estimate of population change, and the Subsequently, additional survey routes have been population status for each species as described by the established, including efforts to get better informa- survey. We also present analyses of multispecies tion from remote regions of the western United groups to summarize patterns of population change States and northern Canada. Alaska also has many for groups of conservation interest. By providing a BBS routes along the limited road system (,70 survey-wide overview of species coverage by the routes sampled each year 1993 to present), but few BBS, this volume complements earlier comprehen- samples prior to 1993. Consequently, Alaska data sive summaries of the BBS (Robbins et al. 1986; cannot be analyzed for time periods comparable Sauer et al. 2003). Detailed regional information to other regions. Alaska trends for recent years regarding population change for all species is have been presented on the BBS Analysis and available on the BBS Summary and Analysis website Summary Website (Sauer et al. 2011), and research (Sauer et al. 2011). is underway to assess the feasibility of developing a combined on- and off-road survey to provide a more A Brief History of the North comprehensive survey of the state (Colleen Handel, American BBS U.S. Geological Survey [USGS], personal commu- nication). BBS-style surveys were conducted in The North American BBS was developed in Puerto Rico from 1997 to 2007, and an expansion response to a need for better information about of the survey into Mexico began in earnest with the population change in songbirds in North America. establishment of routes in northern areas starting Although legal requirements for management of in 2008. harvested species led to the development of conti- By 2010, there were 5,267 survey routes in the nent-scale surveys for waterfowl in the 1950s (Martin database and 3,140 of them were surveyed in 2010. et al. 1979), no such surveys existed for nongame Coverage varies across North America (Figure 1). birds. However, with the publication of Rachel Using routes per degree block as a summary statistic (as Carson’s Silent Spring (Carson 1962) and the ensuing calculated from degree blocks within the current BBS increased public awareness of threats to nongame analysis area, see Maps of Relative Abundance) bird populations, a need quickly became apparent. It comparatively fewer routes occur in the western was evident that the paucity of current information United States (x¯ = 2.73 [95% Confidence interval: about populations of most bird species and the lack 2.62, 2.83], N = 680 west of the 100th meridian and of a scheme by which to collect future data severely 4.53 [4.40, 4.67], N = 658 east of the 100th meridian) limited our ability to assess the consequences of with even fewer in northern Canada (1.64 [1.51, 1.77], pesticides and other stressors on these species. N = 310 north of the 49th parallel and 4.2 [4.11, Chandler S. Robbins, who was already a 4.31], N = 1,029 south of the 49th parallel). distinguished researcher in bird populations at the Patuxent Wildlife Research Center in Laurel, Methods Maryland, was able to convince his superiors in the U.S. Fish and Wildlife Service of the need for a Field methods of the BBS continent-scale monitoring program for nongame BBSs are conducted along roadside survey routes birds. Robbins realized that roadside-based survey composed of 50 independent stops, each stop located methods that he and colleagues had previously used 800 m (0.5 mi) apart. Routes are surveyed once for monitoring mourning dove Zenaida macroura and annually by an observer, generally a volunteer, who American woodcock Scolopax minor could be modified can identify birds by both sight and song. The to count many species simultaneously. He was observer selects a morning in June to conduct the already an influential member of the growing bird- survey (dates in late May are permissible in southern watching community and knew that a competent states and in early July in northern provinces); observer workforce could be recruited for such an observers are encouraged but not required to be effort. Robbins experimented with alternative ap- consistent among years in date chosen to survey the proaches to counting birds for several years before route. The survey commences at a pre-established settling on the protocol that is still used today. He start time (30 min before local sunrise) and the

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Figure 1. Map of route locations in the continental United States and southern Canada. observer progresses to each stop in sequence, survey are available on the BBS operations website parking in a safe pull-off at each. Route maps are (www.pwrc.usgs.gov/bbs/). provided to observers to assist them in finding stops, along with written stop descriptions and GPS Analysis of population change from locations on some routes (Figure 2). BBS data At each stop, the observer exits the vehicle and Constraints on estimation of population change and conducts a 3-min count of all birds heard and those historical analyses. Statistical analysis of BBS data can seen within a 400-m (0.25-mi) radius around the be controversial because complications associated point. The observers record data on data sheets with the nature of the count data and the scale of the provided to them (Figure 3). The same stop locations survey limit the application of standard sample are surveyed in subsequent years to ensure consis- survey methods (e.g., Sauer et al. 2003). The survey tency in sampling, although stops and routes are routes sample local populations, and inference occasionally relocated for reasons related to safety or regarding population change at regional scales access. Supplemental information including weather requires accommodation for 1) repeated counts of variables, disturbance (e.g., number of cars that pass the survey over years on routes, 2) inequities in the stop during the count period), and other data are numbers of samples among regions, 3) missing data also collected during the survey. on routes, and (4) changes in the BBS index After conducting the surveys, observers submit associated with changes in detectability. The issue their data to the respective national BBS offices, of detectability and attendant consequences for where the data are then processed into both raw inference regarding population change have been a and summarized formats for public release via the source of controversy from the start of the BBS. internet. These data, the protocols for conducting Because observers miss a portion of birds when the survey, and additional details regarding the counting, and no means exist in the present protocol

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Figure 2. Stop locations on field map used in Breeding Bird Survey. to estimate directly the fraction of birds missed, Innovations in analyses of BBS data reflect the controlling for factors that influence the proportion advances in computers and statistical methods over of birds counted is a critical component of the the period 1966–2011. In early years of the survey, analysis. Observer differences in counting ability are file storage and computational limitations con- well known to influence detectability (e.g., Sauer et strained analyses to methods such as route regression al. 1994; Kendall et al. 1996), and most analyses of that could be implemented on available computers. BBS data have controlled for observer effects on Modern computer-intensive approaches such as the counts (e.g., Sauer et al. 2008a). hierarchical models presented here provide many

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Figure 3. Breeding Bird Survey field data sheet. opportunities for analyses that more realistically and population change because missing data intro- model the multiscale, repeated-measure nature of duced spurious patterns in change in abundance the survey. (Geissler and Noon 1981; Robbins et al. 1986). To It was evident from the earliest BBS summaries control for effects of missing data, early summaries that comparisons of simple means of counts within of BBS data relied on methods that analyzed regions were an inadequate summary of abundance population change from subsets of data that were

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‘‘comparable’’ over time (i.e., the routes that were subject to these criticisms. Although a modified consistently surveyed by a single observer). Unfor- version of Poisson-based route regression (Link and tunately, methods that estimate change from ratios Sauer 1994) is used to estimate local trend for of counts at different times from small samples of mapping (see Population Change Maps), regional comparable routes produce biased estimates (Geiss- analyses results are now based on hierarchical models. ler and Noon 1981). Geissler and Noon (1981) Hierarchical model analysis. Hierarchical models suggested a route-regression analysis, in which linear provide a comprehensive framework for estimating regression is used to estimate change on individual population change and annual indexes of abundance survey routes and regional trends are computed from BBS data. The hierarchical models we use are as an average of these route-change estimates. In a class of generalized linear mixed models that early applications (Robbins et al. 1986; Geissler permit year, stratum, and observer effects to be and Sauer 1990), route regression was based on a governed by parameters that are random variables. normal regression with natural-logarithm trans- This hierarchical structure allows us to model the formed counts with a 0.5 constant added to influence of regions, observers, and other factors on accommodate zero counts. However, count data the distributions of the parameters influencing from the BBS are more naturally modeled as a counts, rather than on the individual counts generalized linear model, and Link and Sauer (1994) themselves. Using these models, we can formulate defined a Poisson regression with log links fit using regional summaries in terms of model parameters, estimating equations. In both analyses the goal was avoiding the ad hoc weightings used in the route- to estimate rate of change (the slope associated with regression approach. See Link and Sauer (2002) and time), with year and categorical observer data as Sauer and Link (2002) for details of these analyses predictors of the counts. The analysis controlled for and the conceptual issues associated with regional observer effects by allowing a different intercept for models of bird population change. each observer in the analysis (Link and Sauer 1994). Hierarchical models are often fit using Bayesian Interval-specific rate of change (trend) for a region methods, in which inference is based on the posterior was estimated as a weighted average of individual distributions of parameters. Bayesian analyses require route-slopes for the interval of interest, with mean specification of prior distributions of parameters and abundance and survey consistency used as route- the sampling distributions of the data. Although most specific weights and an area weight included to realistic Bayesian analyses are difficult to implement, accommodate regional differences in sample frames simulation-based Markov chain Monte Carlo meth- in multistrata analyses. Variances of these trend ods (MCMC; Lunn et al. 2000) can be used to estimates were estimated by bootstrapping. See approximate the posterior distributions used in Geissler and Sauer (1990) and Link and Sauer Bayesian inference. Using MCMC, posterior distri- (1994) for additional information about the route- butions and associated means, medians, and credible intervals (Bayesian confidence intervals) can be regression method and the weighting factors. calculated iteratively for parameters of interest from Additional analyses estimated annual indexes from many complicated models. Link and Barker (2010) residual variation associated with yearly data around discussed the methods and philosophical basis of the predicted trends (Sauer and Geissler 1990). Bayesian inference. Route regression proved to be a robust approach In the BBS hierarchical model, counts Y for estimation of population change (Thomas 1996) i,j,t (indexed by i for stratum, j for unique combinations but had clear limitations. Although convenient of route and observer, and t for year) are assumed computationally, the route-by-route summaries of to be independent Poisson random variables with change had no direct method to control for within- means l that can be described by log-linear interval variation in the quality of information. i,j,t functions of explanatory variables, Trends could be estimated for a region even if most ~ z { z of the route data were collected during the later log li,j,t Si biðÞt t (1) years of the interval. Because there was no way to v zc zgI ( j,t) ze determine whether route data in a region adequately j( i) i,t i,j,t represented the interval, a trend may have been which are stratum-specific intercepts (S) and slopes based on a preponderance of data from early or late (b), along with effects for observer/route combina- in the interval. The weightings, although constructed tions (v), year (c), start-up (g, with indicator I(j,t) to permit estimation of change for the total that takes value 1 for an observer’s first year of population, were criticized because the weights were survey on a route and 0 otherwise), and over- ad hoc approximations of unknown quantities (ter dispersion effects (e). The model requires specifica- Braak et al. 1994). Estimation in route regression tion of prior distributions for parameters. In our was focused on trend, and annual indexes were analysis, Si and bi are assigned diffuse (essentially flat) computed as residuals of the estimated trends (Sauer normal prior distributions, and other effects are and Geissler 1990), hence annual indexes were also specified as having mean zero normal distributions.

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Observer–route effects (v) are identically distributed predictor and log-transformed annual indexes as the 2 with common variance s v and overdispersion dependent variable. This definition of trend is easily effects (e) are identically distributed with common implemented as a derived statistic in the MCMC 2 variance s e. Variance of the year effects (c)is summaries by calculating a linear regression through the 2 allowed to vary among strata (s c,i). All variances annual indexes derived from each iteration and are assigned flat inverse gamma prior distributions. calculating the percentage change from the estimated From the model parameters, annual indexes of slope parameter associated with year. As with other abundance and trend are defined as derived posterior distributions, median slopes and credible parameters. Stratum-specific annual indexes of intervals are calculated directly from the MCMC results. abundance (ni,t, an index to the number of birds The program WinBUGS (Lunn et al. 2000) was per route in stratum i at year t) incorporate summed used to fit this model, to conduct the MCMC analysis, and exponentiated stratum effects, stratum-specific to evaluate summary statistics to determine when the trend and year effects, and associated variance Markov Chains are converging, and to summarize components added to accommodate asymmetries results. MCMC produces Markov chains that sample in the lognormal distribution: the posterior distribution once they become station- ary. We conducted the analysis for at least 20,000 n ~ i,t iterations to ensure stationary results, and then ð2Þ 2 2 conducted another 20,000 iterations to obtain results exp S z b { z c z 0:5s z 0:5s i i(t t ) i,t v e for estimating the posterior distributions. Some species required additional iterations before usable Stratum totals are Ni,t = Aini,t, where Ai is the area of estimates were obtained; for others, the large data sets the stratum. To obtain indexes for larger areas proved difficult to manage and we could only (groups of strata, e.g., states or countries), we sum summarize 10,000 replicates. For summary, we the Ni,t over the relevant i. For presentation, ‘‘thinned’ the resulting chains by a factor of 2 (i.e., composite indexes Nt are scaled by the total areas, using every second observation for calculating obtaining a summary on the scale of birds per route, estimates and credible intervals). We also output the ,X ~ MCMC replicates and used them to compute nt Nt i Ai . The strata are the regions formed by the intersection of Bird Conservation Regions regional summaries using FORTRAN programs. (BCRs; e.g., Sauer et al. 2003; see Population Change Summary) within states or provinces. For Population change summary summary, results from these areas are combined to Trend and annual index results are the primary provide indexes at the scale of states, provinces, summary information for species from BBS analyses. BCRs, and the entire survey area. Here, we present long-term composite trend results We define trend as an interval-specific geometric (B¯ ), for the intervals 1966 to 2011 and 2001 to 2011. mean of proportional changes in population size, Since the survey was implemented at different times expressed as a percentage (cf., Link and Sauer 1998). in different regions, trend estimates and indexes Thus the trend from year ta to year tb for stratum i is were computed using the first year in which data 100(Bi 2 1)%, where were available for the species; that is, western species

1 with no data prior to 1968 have trend estimates { tb ta ni,tb based on the interval 1968–2011. A regression-based Bi~ ð3Þ ni,ta trend estimate is provided for comparison to the long-term trend results. Annual indexes (ni) are The composite trend B¯ is calculated analogously estimated at the survey-wide scale; the birds/route as 100(PB¯ 2 1)%, using the composite indexes scaling of these indexes is not interpretable as an Nt~ Ni,t, absolute abundance because it is not associated with i a known area (Thogmartin et al. 2006). 1 { N tb ta We use BCRs as components of strata (Sauer et al. ~ tb B ð4Þ 2003; Sauer and Link 2011). However, the BBS was Nta originally stratified and coordinated within states and This definition of trend is interval specific and is provinces, and observation of the map of route applicable for estimation of change for any interval. locations (Figure 1) indicates that states and provinces However, many alternative definitions of trend exist, vary greatly in number of survey routes per unit area. and some investigators prefer a definition of trend as To accommodate this state-specific variation in the slope of a regression line through annual indexes samples per unit area, we retained states and (e.g., Thomas et al. 2004). Using estimates from our provinces as a component of the stratification. model, we calculate this alternative estimate of trend Consequently, BCRs within states or provinces form as the slope of a linear regression with time as a our primary strata, and we aggregated these regions

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 8 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. to estimate composite trends within states, provinces, Many investigators have used bird survey data to BCRs, and larger-scale regions. develop contour maps of bird abundance based on Visualization of trends across regions is complicated mean counts on survey routes. Root (1988) provided by the large differences in precision among the regions. a grid of smoothed relative abundances for species For each species, we estimated trends from 1966 to observed on Christmas Bird Counts. Sauer and 2011 for state and provinces and for BCRs, and we Droege (1990) mapped relative abundances of summarize results in figures that document the eastern bluebirds Sialia sialis just after severe winters estimated trend and 95% CI, using a hierarchical in the mid-1970s and after their populations model to order the trends by magnitude and estimate returned to prewinter levels. Relative abundance number of regions with decreasing populations (Sauer maps have also been used to document the ranges of and Link 2002). species (e.g., Droege and Sauer 1990; Sauer et al. The hierarchical model for estimation of popula- 1995). See Sauer et al. (1995) for applications and tion change requires sufficient samples across the discussions regarding mapping of survey data. region and time period of interest to allow estimation We present maps as descriptive summaries of of the time series, and occasionally regions with current relative abundance over space. These maps limited data either will not converge or will provide are based on simple averages of counts on routes extremely imprecise estimated trends. To limit the over time. Although similar data have been used as influence of these regions on the overall analysis, we the basis of population estimates from BBS data, no screen composite summaries to remove regions that method exists to control for observer differences in provide little information but greatly increase the counting ability or for other factors such as roadside- size of the credible intervals (Sauer and Link 2011). counting effects, time-of-day effects, or species- Regions with very small samples, or with data that specific effective survey areas (Thogmartin et al. did not span the interval of interest, produced very 2006). These factors add imprecision and possible imprecise results, and inclusion of these results bias in estimation of route-specific and regional occasionally led to extremely imprecise regional abundance (Sauer et al. 1994). BBS data are edited estimates. We identify regional estimates that should to remove data that are of questionable quality or be viewed with concern using quality criteria based that represent birds thought to be migrating rather on sample sizes and precision as indicated by large than breeding; edges of ranges from these maps thus credible intervals (Sauer et al. 2011). Sample sizes exclude observations of birds considered to be are defined in terms of number of random BBS nonbreeding. routes on which the species was encountered. A To construct the maps, we used the center points small number of nonrandom routes exist in the of BBS routes, estimated as the midpoints of survey database but were not used in the analysis. digitized route paths (Sauer et al. 2011), as the Small sample sizes (,50) are flagged for caution. geographic location of the survey route. Although Very small samples (,14) are flagged as possibly BBS routes meander over 39.4 km, center points of unreliable. We classify estimated trends as imprecise route paths have been used to characterize route if their credible intervals are sufficiently wide that locations in geographic analyses (e.g., Flather and a median change of 3% per year change would Sauer 1996). Current relative abundance of birds include 0 (i.e., 0.5[CIu 2 CIl] . 3). We define of each species on the routes was estimated as an extremely imprecise trends as those whose credible average of counts on the route from the interval intervals are sufficiently wide that a median change 2007–2011. We used inverse distancing (Isaaks of 5% per year change would include 0. and Srivastava 1989) to interpolate estimated abundances for the map. This procedure estimates Maps of relative abundance the abundance at a location as a distance-weighted Mapping relative abundance from BBS data has average of counts from nearby survey routes. The been of interest from the start of the survey, and distance weighting places more influence on several generations of maps have been provided to nearby routes. For each point on an evenly spaced users via publications and the internet (e.g., Robbins grid of points overlaid on the survey area, we used et al. 1986; Sauer et al. 2011). Here, we update these inverse distancing to estimate relative abundance maps using current data to model regional patterns ofaspeciesbasedondatafromthenearest15 of abundance within the boundaries of the surveyed survey routes, and then displayed the estimated area. Isaaks and Srivastava (1989:42) suggest that abundances for each surrounding square cell in the summary contour maps be viewed ‘‘as helpful grid as our map. The grid was created in Arc/Info qualitative displays with questionable quantitative (Environmental Systems Research Institute 1991) significance.’’ Their context of discussion was with grid cells having sides of length 21,475 m. We geological data, but the comment is likely at least categorized relative abundances as: 0.05 to 1, .1 as relevant for maps of bird survey data from the to 3, .3to10,.10 to 30, .30 to 100, and .100 BBS. birds per route, and shaded the map by succes-

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 9 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. sively darker reds in each category. The minimum our summary maps; the area to the north of the level of 0.05 was chosen as the edge-of-range index survey region is stippled on the maps. The southern after some comparisons of contours with known edge of the survey was defined as the southern edges of ranges (S. Droege and D. Bystrak, USGS border of the contiguous United States. Patuxent Wildlife Research Center, personal We overlaid the BBS abundance maps on communication), and the larger cut-points were breeding range maps for the western hemisphere chosen as a series of powers of 3, rounded up for prepared by NatureServe (Ridgely et al. 2007; www. ease of presentation. To prevent extrapolation natureserve.org/getData/birdMaps.jsp). The pro- beyond the area of consistent data, a northern portion of the total breeding and resident range edge of the surveyed area was defined by buffering covered by the BBS was calculated. Because the routes on the northern edge of the survey area and NatureServe maps do not contain relative abun- defining the edge as the perimeter of the polygon dance information, we could not calculate the formed by the overlapping polygons (cf., Sauer proportion of the total species’ population surveyed and Link 2011). by the BBS. A reviewer has pointed out that NatureServe maps are occasionally inaccurate; Population change maps metadata are available at http://www.natureserve. As a summary of spatial pattern in the data, we org/getData/Metadata_Birds_ver_3.0_Oct_07.pdf, estimated population change maps to provide a but we caution that for some species (e.g., the simplified visual alternative to the more rigorous coastal species such as pelagic cormorant Phala- quantitative estimates of regional change provided crocorax pelagicus) and for the grouped species, these by hierarchical models. Population change maps number are likely to be imprecise. were also based on predictions at the grid center points. For each species, we estimated population Classification of species into groups change for a grid cell using a route regression The United States ‘‘State of the Birds’’ Report analysis on nearby routes with data. Population (U.S. North American Bird Conservation Initiative change was estimated on each route using estimating [NABCI] Committee 2009) used composite summa- equations, and grid-cell trends were estimated as an ries of population change for groups of bird species abundance- and precision-weighted average of trend as indicators of environmental health. They (U.S. estimates from the nearest 15 routes. Estimated NABCI Committee 2009) categorized bird species by population change (percent per year) was catego- major habitats (aridland; eastern, western, boreal, and rized as ,21.5, 21.5 to 20.25, .20.25 to 0.25, subtropical forest; grassland; urban and suburban; .0.25 to 1.5, and .1.51. As this procedure will not wetland; and marsh). For each habitat an inclusive list provide results that are constrained to edges of of species occurring in the habitat was developed; for species’ ranges, we chose to truncate population many of the habitats obligate species that primarily change maps to grid cells where the estimated used the habitat were also defined. Widespread species abundance based on data from 1993 to 2011 was that occur in three or more major habitats were .0.05. Use of abundance data from the longer categorized as generalists. Birds were also grouped interval allowed for depiction of trends from areas by migration status: permanent residents, temperate where the species may no longer occur. migrants, and neotropical migrants. Finally, exotic We note that more sophisticated methods of (nonnative) species were considered as a group. See spatial mapping are available (e.g., Thogmartin et al. the Report (U.S. NABCI Committee 2009) or the 2004). These methods have not yet been fully State of the Birds Website (www.stateofthebirds.org) implemented for BBS data, primarily due to for additional information on these groups. logistical limitations. We are presently evaluating methods for estimating trends for spatial models that Composite summary by species groups use a grid-based spatial structure similar to that used For each group of species, we constructed a in our inverse-distancing analysis (F. Bled, Colorado composite summary of population change using a State University, personal communication). method similar to that described by Gregory et al. (2005). Gregory et al. (2005) defined a composite Proportion of species’ range in the summary as a geometric mean of scaled (to a base BBS area year) population trajectories for species in the group. We used the relative abundance map of each As BBS results vary greatly in quality of information, species to estimate the proportion of its breeding simple averages of estimates are dominated by range covered by the BBS. We developed a northern extreme, yet imprecise, estimates (e.g., Sauer and edge of the surveyed BBS area by buffering the Link 2002). We modified a hierarchical model center point of BBS routes with a 12.5-mi circle and described by Sauer and Link (2002) to summarize defining the edge as an arc with nodes defined as the collections of trend estimates and used this to northern edge of these buffers. This edge appears on estimate the mean of the collection of trends. This

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 10 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. model has the benefit that the mean is based on the 42 y with associated credible interval; 3) an indicator parameters, not on the often imprecise estimates. graph of composite total change, the yearly exp(m)as To be consistent with the Gregory et al. (2005) already described; and 4) a graphical summary and long-term summaries of change (rather than yearly listing of 1966–2011 trend estimates for each of the changes as defined in Sauer and Link 2002), the constituent species. model assumes that the logarithms of the estimates Summary of individual species results by taxonomic ˆ of change parameters (Bs), for s = 1,…, n species are grouping. We provide overviews of population change ˆ 2 normally distributed, {i.e., [ln(bs|bs, s s]=N[ln(bs), by taxonomic groupings at the level of subfamily or 2 s s]}; and distributions for the bs are lognormal family. We list species analyzed for the group, describe 2 2 {[ln(bs)|m, t ]=N(m, t )}. Note that this model is notable long-term, survey-wide trends, and provide a applied to each year; year subscripts are suppressed. brief commentary on the value of the survey for the We used this model in a Bayesian analysis, assuming taxa. We also note species that have been identified as noninformative priors for the m and t parameters. being of conservation concern, using the inclusive We applied the model to data for each year starting definition of conservation concern used in the State of from a base year of 1968 for each group of species the Birds 2009 report (U.S. NABCI Committee 2009). and estimated the posterior distributions of the We adopt the convention of referring to positive (or exponentiated trend parameters. We present medi- negative) estimates of change if the 1966–2011 change ans and percentile credible intervals of the posterior estimates are .0(or,0); we consider the results to be distributions of exp(m) for each year as the composite significant if the credible intervals of the interval change from the base year to that year. We plot estimates do not overlap 0. Taxonomy and order of these results as the composite summary for each presentation follow the American Ornithologists’ group. Union Check-list of North American Birds 52nd See Link and Barker (2010:85–93) for an Supplement (Chesser et al. 2011). informative discussion regarding use of hierarchical Taxonomic changes over the BBS survey period models to estimate number of regions with increas- introduce complications for management and sum- ing populations. While these methods were devel- mary of the BBS. In particular, several species have oped for ranking species rather than regions within been split into multiple species by taxonomists. For species, we applied them here as an exploratory tool some of these species, early data collected from areas to permit readers to evaluate regional consistency of of sympatry cannot be discriminated adequately to declines. permit contemporary range-wide species-level anal- yses, and updating the database and analyses can be Presentation of results time-consuming and controversial. Western and Species accounts. We integrate and present Clark’s grebes, Aechmophorus occidentalis and Aechmo- information for individual species as species phorus clarkii, respectively, and Cordilleran and accounts (Appendix A). Species Accounts provide Pacific-slope flycatchers, Empidonax occidentalis and summary statistics and visually oriented summaries Empidonax difficilis, respectively, are presently ana- of overall pattern, via 1) general information lyzed as single taxa. We also produce species including proportion of the species’ range that is accounts for two groups of species, for which surveyed; 2) population trend results from 1966– individual species results are also presented: alder 2011 and 2001–2011; 3) abundance maps; 4) and willow flycatchers, Empidonax alnorum and population change graphs; 5) population change Empidonax traillii, respectively (formerly considered maps; 6) state and provincial population trend to be a single species named ‘‘Traill’s flycatcher’’ summaries from 1966 to 2011; and 7) BCR Empidonax traillii), and yellow-bellied, red-naped, and population trend summaries from 1966 to 2011. red-breasted sapsuckers, Sphyrapicus varius, Sphyrapicus For the regional summaries (items 6 and 7), we nuchalis, and Sphyrapicus ruber, respectively. provide graphics of trend results ranked by magnitude of trend, excluding regions with highly Results imprecise estimates ([half-width of CI] . 5) or with limited samples (N , 5 routes in the region). Summary of individual species results Species group summaries. Species group summaries Appendix A provides accounts for the 426 species (Appendix B) are presented for indicator and and two species groups. Over the 1966–2011 period, migration status species groups. For each species 242 of the 426 species we considered in our analysis group, we present 1) overview information on the had negative trend estimates (Figure 4). The Bayes- group (geographic scope, N of species, percentage of ian estimate of percentage of declining species from species for which BBS provided information, and 1966 to 2011 (Sauer and Link 2002) was 56.8% average percent ranges of the analyzed species in the (52.3, 61.0). Of these, 153 species experienced BBS survey area); 2) a population change summary significant declines (i.e., those with credible intervals detailing the total percentage composite change over that did not include 0), and 90 of the 184 species

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Figure 4. Estimated annual trends and 95% credible intervals for 426 species of North American birds for the interval 1966–2011, ranked from most declining to most increasing. For clarity of presentation, individual species are not identified. with positive trend estimates experienced significant Limited data exist on whistling-ducks from the increases. Over the 2001–2011 interval, 146 of the BBS, and the small portion of their breeding ranges 426 species we considered in our analysis had (2.1%) contained in the United States are likely of negative trend estimates (Figure 5), and 58 species limited value in assessing the overall population experienced significant declines (i.e., those with status of the species. In the BBS survey area, both credible intervals that did not include 0). Bayesian species show positive estimates of change between estimate of percentage of declining species for 2001 1966 and 2011, although trends were significant to 2011 was 40.1% (34.3, 46.2). Over the same only for the black-bellied whistling-duck. interval, 272 (64%) of the 426 species had positive Geese and swans. Order: Anseriformes, Family: trend estimates, and 116 of these species experienced Anatidae, Subfamily: Anserinae (Canada goose Branta significant increases. canadensis, mute swan Cygnus olor) Both Canada goose and mute swan are increasing Taxonomic summaries in the BBS survey area, and for both species the BBS Whistling-ducks. Order: Anseriformes,Family:Anatidae, analysis indicates that positive trends occur in all Subfamily: Dendrocygninae (black-bellied whistling-duck states, provinces, and BCRs. The BBS clearly shows Dendrocygna autumnalis, fulvous whistling-duck Dendrocygna the dramatic and significant increase of Canada bicolor) goose in the United States and southern Canada.

Figure 5. Estimated trends and 95% credible intervals for 426 species of North American birds for the interval 2001– 2011, ranked from most declining to most increasing. For clarity of presentation, individual species are not identified.

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Mute swan results reflect the imprecision associated declining. California quail are significantly increas- with low observation rates. ing (1.7%/y), and Gambel’s quail appear stable. Ducks. Order: Anseriformes, Family: Anatidae, Pheasants. Order: Galliformes, Family: Phasianidae Subfamily: Anatinae (wood duck Aix sponsa, gadwall (chukar Alectoris chukar, gray partridge Perdix perdix, Anas strepera, American wigeon Anas americana, ring-necked pheasant Phasianus colchicus) American black duck Anas rubripes, mallard Anas Three exotic pheasant species have their entire platyrhynchos, mottled duck Anas fulvigula, blue-winged (introduced) North American ranges surveyed by teal Anas discors, cinnamon teal Anas cyanoptera, the BBS. Ring-necked pheasant and gray partridge northern shoveler Anas clypeata, northern pintail Anas are experiencing declines in many states, provinces, acuta, green-winged teal Anas crecca, canvasback Aythya and BCRs; overall trends are negative, with a valisineria, redhead Aythya americana, ring-necked duck significant decline (21.5%/y) occurring in gray Aythya collaris, lesser scaup Aythya affinis, bufflehead partridge populations. Chukar populations are Bucephala albeola, common goldeneye Bucephala stable. clangula, Barrow’s goldeneye Bucephala islandica, Grouse and prairie chickens. Order: Galliformes, Family: hooded merganser Lophodytes cucullatus, common Phasianidae, Subfamily: Tetraoninae (ruffed grouse merganser Mergus merganser, red-breasted merganser Bonasa umbellus, greater sage-grouse Centrocercus Mergus serrator, ruddy duck Oxyura jamaicensis) urophasianus, dusky grouse Dendragapus obscurus, sooty We present results for 22 species of ducks. On grouse Dendragapus fuliginosus, sharp-tailed grouse average 55% of the breeding ranges of these species Tympanuchus phasianellus, greater prairie-chicken are covered by the BBS. However, the wetland Tympanuchus cupido) habitats they frequent are often poorly represented The ranges of these grouse are largely covered by along BBS routes, and hence the species show low the BBS. We do not present results from the limited relative abundances; seven show imprecise survey- data available for lesser prairie chicken Tympanuchus wide trend estimates. The U.S. Fish and Wildlife pallidicinctus, Gunnison’s sage grouse Centrocercus Service and Canadian Wildlife Service conduct minimus, or ptarmigan species Lagopus spp. Several more comprehensive waterfowl surveys of the grouse species are of conservation concern: greater primary breeding ranges of these species, but BBS sage-grouse has a declining population with a data are useful in showing regional population significant, although imprecisely estimated, trend of changes in portions of the continental United States 23.6%/y; sooty grouse is declining significantly at not covered by the extensive surveys. In particular, 21.6%/y; dusky grouse shows a nonsignificant wood duck results from the BBS are used as the increase; and greater prairie chicken has a positive, primary source of population status information for but very imprecise, estimate of population change. that species. The BBS covers 96% of wood duck Wild turkey. Order: Galliformes, Family: Phasianidae, breeding range and documents significant increases Subfamily: Meleagridinae from 1966 to 2011. Increases are also noted for The BBS indicates significant (8.4%/y) increases gadwall, for which 99% of the breeding range is in the wild turkey Meleagris gallopavo population covered by the survey, and hooded merganser, for across the 90% of its range that falls within the which 92% of the breeding range is covered. BBS survey area. Mottled duck, a watchlist species, shows significant Common loon. Order: Gaviiformes, Family: Gaviidae declines, due primarily to declines in the western Only 31% of the range of common loon Gavia immer portions of its range. American wigeon, cinnamon falls within the BBS survey area, and populations teal, and lesser scaup also show significant declines, among states, provinces, and BCRs show positive but as does red-breasted merganser according to its very not significant trends. limited data. Northern pintail show declines from Grebes. Order: Podicipediformes, Family: Podicipedidae the regression trend estimate, but a large increase in (pied-billed grebe Podilymbus podiceps, horned grebe the index for 2011 caused the CI for the interval Podiceps auritus, red-necked grebe Podiceps grisegena, estimate to overlap 0. eared grebe Podiceps nigricollis, western and Clark’s Quail. Order: Galliformes,Family:Odontophoridae grebes [combined]). (mountain quail Oreortyx pictus, scaled quail Callipepla The BBS provides information on all grebe species squamata, California quail Callipepla californica, Gambel’s except least grebe Tachybaptus dominicus, although on quail Callipepla gambelii, northern bobwhite Colinus average only 43% of their ranges are covered. Clark’s virginianus) grebe is a species of conservation concern, in We present survey results for five quail species, composite with western grebe the populations are which on average have 75% of their ranges in the not significantly declining overall although results are BBS survey area. Of the three species of conserva- imprecise. Horned grebe is significantly declining at tion concern, mountain quail appears stable in the 1.8%/y across the 39% of the species’ range that BBS analysis, although scaled quail (23.1%/y) and occurs in the BBS region. northern bobwhite (24.2%/y) are significantly Wood stork. Order: Ciconiiformes,Family:Ciconiidae

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Wood stork Mycteria americana is not well monitored relatively large numbers on limited numbers of by the BBS, with very imprecise results, and ,1% of routes and are also variable over time. This leads to the species breeding range occurs in the survey area. imprecision in results, and white ibis is the only Cormorants. Order: Suliformes,Family:Phalacrocoracidae species with relatively precise results. While BBS (double-crested cormorant Phalacrocorax auritus,pelagic indexes likely provide a reasonable description of cormorant) change over time, the large and imprecisely We present results for two species of cormorants. estimated indexes are much larger than mean counts Double-crested cormorants are widespread in the on a route. contiguous United States and southern Canada and Roseate spoonbill. Order: Pelecaniformes, Family: are increasing in 93% of states, provinces, and Threskiornithidae, Subfamily: Plataleinae BCRs. The BBS covers 74% of the species’ range. Although imprecise, BBS results indicate rapidly Trends for pelagic cormorant are poorly estimated increasing populations (7.6%/y) for the very limited from data from only 20 survey routes. part of the roseate spoonbill Platalea ajaja breeding Anhinga. Order: Suliformes, Family: Anhingidae range (1.1%) that falls in the BBS area. The small part of the anhinga Anhinga anhinga Vultures. Order: Accipitriformes, Family: Cathartidae breeding range that falls within the BBS area (4%) (black vulture Coragyps atratus, turkey vulture Cathartes contains increasing populations, particularly in aura) recent years. Both vulture species monitored by the BBS have Pelicans. Order: Pelecaniformes, Family: Pelecanidae large breeding ranges in the neotropics, and the BBS (American white pelican Pelecanus erythrorhynchos, provides information from the northern edge of their brown pelican Pelecanus occidentalis) ranges. Black vulture (4.8%/y) and turkey vulture American white pelican has 88% of its range in (2.4%/y) show rapidly and significantly increasing the BBS survey area and has a generally increasing populations in the BBS survey area. population, although change is imprecisely estimated Osprey. Order: Accipitriformes, Family: Pandionidae from BBS data. Brown pelican is a coastal species, About half the breeding range of osprey Pandion and thus BBS data are very limited and imprecisely haliaetus falls into the BBS area, although this water- estimated; however, BBS data also indicate a long- dependent species is generally encountered at very term significant increase for the species of 5.4%/y. low abundances. This species has been significantly Herons, egrets, and bitterns. Order: Pelecaniformes,Family: increasing (2.5%/y) across the surveyed area. Ardeidae (American bittern Botaurus lentiginosus,least Kites, hawks, and eagles. Order: Accipitriformes,Family: bittern Ixobrychus exilis, great blue heron Ardea herodias, Accipitridae (swallow-tailed kite Elanoides forficatus,white- great egret Ardea alba,snowyegretEgretta thula, little blue tailed kite Elanus leucurus, Mississippi kite Ictinia heron Egretta caerulea, tricolored heron Egretta tricolor, mississippiensis, bald eagle Haliaeetus leucocephalus, cattle egret Bubulcus ibis, green heron Butorides virescens, northern harrier Circus cyaneus, sharp-shinned hawk black-crowned night-heron Nycticorax nycticorax, yellow- Accipiter striatus, Cooper’s hawk Accipiter cooperii,northern crowned night-heron Nyctanassa violacea) goshawk Accipiter gentilis, Harris’s hawk Parabuteo With the exception of reddish egret Egretta unicinctus,red-shoulderedhawkButeo lineatus,broad- rufescens, which is not surveyed by the BBS, these winged hawk Buteo platypterus, Swainson’s hawk Buteo wading birds are well represented in BBS results. On swainsoni, red-tailed hawk Buteo jamaicensis,ferruginous average 40% of the species’ ranges are covered by hawk Buteo regalis,goldeneagleAquila chrysaetos) the BBS. Wetland habitat use and, for some species, This heterogeneous group shows a wide variety of colonial nesting habits limit observability from roads; population trends. Mississippi kite’s range is almost not surprisingly, a few species have very low entirely within the BBS region, and it tends to be abundances along survey routes. Significant declines increasing except in the western part of the range occur in little blue heron (21.2%/y), cattle egret leading to an overall estimate of no change. (21.0%/y), and green heron (21.6%/y); seven Swallow-tailed kite is significantly increasing in the other species have nonsignificant declining popula- 3% of its range monitored by the BBS, and white- tions. Great blue heron (0.8%/y) and great egret tailed kite shows no change in the 4% of its range (2.5%/y) show significantly increasing populations. covered by the BBS. Bald eagle, recently removed Ibis. Order: Pelecaniformes, Family: Threskiornithidae, from the endangered species list, has increased Subfamily: Threskiornithinae (white ibis Eudocimus albus, dramatically (5.4%/y) over the survey interval glossy ibis Plegadis falcinellus, white-faced ibis Plegadis although it is still rare on BBS routes. Northern chihi) harrier has been significantly declining overall Ibis species have all been increasing overall in the (20.9%/y) although regional variation occurs in its BBS survey area, but white ibis and white-faced ibis trends. All accipiters are infrequently encountered each have only a quarter of their breeding ranges in on BBS routes; Cooper’s hawk has 97.4% of its the survey area, while glossy ibis has about 44% of range in the BBS area and shows a significant 2.4%/ its range in the BBS area. Ibis tend to be seen in y increase over the survey interval. Among buteos,

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Harris’s hawk, the only southwestern species, shows Sandhill crane. Order: Gruiformes, Family: Gruidae, a significant decline (21.9%/y) in the 6% of its Subfamily: Gruinae range covered by the BBS. Other buteos show About a third of the sandhill crane Grus canadensis significantly increasing populations survey-wide and breeding range is monitored by the BBS, which have large portions of their ranges within the BBS shows a significant 5.3%/y long-term increase for survey area. Golden eagle shows generally stable the species. populations within the 42% of its range covered by Plovers. Order: Charadriiformes, Family: Charadriidae, the BBS. Subfamily: Charadriinae (killdeer Charadrius vociferus, Crested caracara. Order: Falconiformes, Family: mountain plover Charadrius montanus) Falconidae Subfamily: Caracarinae Both killdeer (21.2%/y) and mountain plover Crested caracara Caracara cheriway is another (23.0%/y) show significant declines over the 1966– species whose primary breeding distribution is south 2011 period, although for both species the declines of the BBS survey area. The species is significantly appear to be less severe during the recent period increasing in Texas and Florida. (2001–2011). Killdeer is likely well monitored over Falcons. Order: Falconiformes, Family: Falconidae, the 73% of its range that falls in the BBS area. Even Subfamily: Falconinae (American kestrel Falco though their entire breeding range is in the BBS sparverius, merlin Falco columbarius, peregrine falcon area, mountain plover is considered to be poorly Falco peregrinus, prairie falcon Falco mexicanus) monitored by the BBS, with imprecise results due Of the falcons, American kestrel is the best largely to small sample sizes and poor coverage of surveyed by the BBS, having 40% of its range in their habitats from roadsides (U.S. Department of the survey area and average relative abundance of the Interior 2011). about 1 bird/route; its population is significantly Stilt and avocet. Order: Charadriiformes,Family:Recur- declining (21.5%/y) over the sample area. The virostridae (black-necked stilt Himantopus mexicanus, prairie falcon population is increasing (although not American avocet Recurvirostra americana) significantly with the interval-based CI) over the Black-necked stilt has increased significantly 86% of the range covered by the BBS, although the (2.8%/y) in the 13% of its range that falls in the species is encountered only infrequently (0.1 birds/ BBS area; American avocet is generally stable over route). The BBS covers only 30% of the breeding the 93% of its range that is monitored by the BBS. ranges of peregrine falcon and merlin. Merlins are Sandpipers. Order: Charadriiformes,Family:Scolo- significantly increasing (3.1%/y); peregrine falcon pacidae, Subfamily: Scolopacinae (spotted sandpiper trends are positive, but imprecisely estimated. Actitis macularius, solitary sandpiper Tringa solitaria, Rails, gallinules, and coot. Order: Gruiformes, Family: greater yellowlegs Tringa melanoleuca,willetTringa Rallidae (clapper rail Rallus longirostris, king rail Rallus semipalmata, lesser yellowlegs Tringa flavipes,upland elegans, Virginia rail Rallus limicola, sora Porzana carolina, sandpiper Bartramia longicauda, long-billed curlew purple gallinule Porphyrio martinica, common gallinule Numenius americanus,marbledgodwitLimosa fedoa, Gallinula galeata, American coot Fulica americana) Wilson’s snipe Gallinago delicata, American woodcock) The BBS provides the only long-term information Greater yellowlegs and lesser yellowlegs breed on breeding populations of rails; hence the informa- primarily outside the BBS area, but the limited data tion is often cited even though the survey is not well- from the BBS for lesser yellowlegs from prairie suited for monitoring these poorly detected marsh Canada indicate a significant population decline birds. Of the four rail species, the significantly (25.3%/y) for this species of conservation concern. declining (24.0%/y) king rail and the nonsignifi- Solitary sandpiper, also a bird of conservation cantly declining clapper rail are of conservation concern, has similarly limited BBS coverage and concern. Virginia rail was rarely encountered on the very imprecise results. Willet breeds within the BBS 392 BBS routes from which they have been region, and its population has been stable during the recorded, while sora has been detected on 989 BBS survey interval. Spotted sandpiper is wide- BBS routes. Both species show positive but nonsig- spread in the BBS area, which covers 60% of its nificant trends. Only 25% of the clapper rail range is range, and is significantly declining (21.4%/y) over in the BBS survey area, although the ranges of the most of the surveyed area. Upland sandpiper, long- other rail species are well covered (.69%) by the billed curlew, and marbled godwit are all species of BBS. Purple gallinule and common moorhen conservation concern, and the BBS covers most of Gallinula chloropus show nonsignificant population their ranges. BBS indicates generally increasing declines in the small part (,30%) of their range that (0.5%/y) upland sandpiper populations over most occurs in the BBS area. American coot has of the breeding range, and data show no evidence of experienced large population fluctuations during significant declines for the other species. Half of the the 1966–2011 BBS period and has no significant Wilson’s snipe breeding range is covered by the BBS trend overall; 77% of its range is covered by the and, although the survey-wide estimates indicate no BBS. change, midcontinent populations of the species are

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 15 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. increasing while western and eastern populations are BBS, has very imprecise trend estimates from BBS declining. American woodcock are rarely encoun- data. tered on BBS routes, but indications of decline in the Doves and pigeons. Order: Columbiformes, Family: regression-based summary of the BBS are consistent Columbidae (rock pigeon Columba livia, band-tailed with results from the Singing-ground Survey that the pigeon Patagioenas fasciata, Eurasian collared-dove U.S. Fish and Wildlife Service and Canadian Streptopelia decaocto, white-winged dove Zenaida asiatica, Wildlife Service conduct each spring for the species mourning dove, Inca dove Columbina inca, common (Sauer et al. 2008b). ground-dove Columbina passerina) Wilson’s phalarope. Order: Charadriiformes, Family: Doves and pigeons are visible species that are easy Scolopacidae, Subfamily: Phalaropodinae to detect along BBS routes. Two exotic species are Wilson’s phalarope Phalaropus tricolor is encoun- encountered by BBS observers. The rock pigeon is tered on a moderate number of BBS routes over the widespread and has been experiencing small 93% of its range occurring in the BBS survey area, (21.0%/y), but significant declines over the BBS and populations appear stable. interval, although regional results suggest that Gulls. Order: Charadriiformes, Family: Laridae, declines are centered in the eastern United States Subfamily: Larinae (laughing gull Leucophaeus atricilla, with a mosaic of increase and declines elsewhere. Franklin’s gull Leucophaeus pipixcan, ring-billed gull Eurasian collared-dove is increasing significantly Larus delawarensis, western gull Larus occidentalis, everywhere at extremely high rates, although it has California gull Larus californicus, herring gull Larus not yet colonized northern parts of the continent. argentatus, glaucous-winged gull Larus glaucescens, great Common ground-dove and Inca dove are southern black-backed gull Larus marinus) species with only parts of their ranges in the BBS Interpretations of gull data from the BBS tend to area, and both of them appear to be increasing at be somewhat controversial because these species the northern edges. Common ground-dove is often have only the margins of their ranges covered declining in Florida but is stable elsewhere; Inca by the BBS and birds are found in flocks or as doves are significantly increasing in Texas and flyovers, all of which leads to imprecise data. Louisiana. Three harvested species are monitored Glaucous-winged gull and great black-backed gull by the BBS and by U.S. Fish and Wildlife Service have ,10% of their range in the BBS area and (USFWS) surveys. Mourning dove is widespread nonsignificant population trends. Three other spe- and abundant; BBS indicates an overall decline cies have ,30% of their ranges in the survey area. (20.4%/y) of the species but with increases in the north- Of these, the western gull has very limited data; eastern part of the survey. Band-tailed pigeon is herring gull appears to be significantly declining declining significantly (22.4%/y) in the 46% of its overall (23.8%/y), albeit with imprecise estimates; breeding range in the BBS area, and white-winged dove and laughing gull has an increasing population is increasing in most states, but not significantly overall. (2.8%/y). Of the gull species with .70% of their Cuckoos. Order: Cuculiformes,Family:Cuculidae,Sub- breeding ranges in the BBS area, Franklin’s gull family: Cuculinae (yellow-billed cuckoo Coccyzus americanus, shows significant declines (24.2%/y), ring-billed gull black-billed cuckoo Coccyzus erythropthalmus) shows a significant population increase (3.0%/y), Populations of both yellow-billed cuckoo (21.5%/ and California gull shows a nonsignificant decline. y) and black-billed cuckoo (23.1%/y) are significantly Terns. Order: Charadriiformes,Family:Laridae, declining in the BBS survey area, although estimates Subfamily: Sterninae (least tern Sternula antillarum, gull- from the latter are quite imprecise. billed tern Gelochelidon nilotica, Caspian tern Hydroprogne Greater roadrunner. Order: Cuculiformes, Family: caspia,blackternChlidonias niger, common tern Sterna Cuculidae, Subfamily: Neomorphinae hirundo,Forster’sternSterna forsteri, royal tern Thalasseus Greater roadrunner Geococcyx californianus, which maximus) has 62% of its breeding range in the BBS area, Terns are, with one exception, poorly monitored shows no significant trend from BBS data. by the BBS. Gull-billed tern, royal tern, and least Groove-billed ani. Order: Cuculiformes, Family: tern have ,15% of their breeding ranges covered by Cuculidae, Subfamily: Crotophaginae the BBS, and have imprecise results. Caspian tern, Groove-billed ani Crotophaga sulcirostris has only Forster’s tern, and common tern, with ranges 4% of its range in the BBS area (in south Texas), and covered 48%–93% by the BBS, also have imprecise trends for the species are imprecisely estimated from results. Black tern is the exception because its BBS data. populations show significant declines over the Barn owl. Order: Strigiformes, Family: Tytonidae .80% of its range covered by the BBS. Owls are not a target group for the BBS. Except Black skimmer. Order: Charadriiformes, Family: for accidental observations, they generally are only Laridae, Subfamily: Rynchopinae detectable during the first few stops of a BBS route Black skimmer Rynchops niger, which is a coastal due to their largely nocturnal and crepuscular species with only 1% of its range covered by the activity patterns. Barn owls Tyto alba are seen at

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 16 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. extremely low abundances on a relatively small Black swift is a species of conservation concern. number of survey routes on the 23% of their The BBS shows significant decline (26.8%/y) (western hemisphere) range occurring in the survey although with imprecise estimates across the 35% area. The BBS trend estimates suggest a recent of the species’ range in the BBS area. Chimney swift (2001–2011) increase in the species’ population. is also declining significantly (22.3%/y), and .99% Typical owls. Order: Strigiformes, Family: Strigidae of their range is covered by the BBS. Vaux’s swift (western screech-owl Megascops kennicottii, eastern and white-throated swift show nonsignificant de- screech-owl Megascops asio, great horned owl Bubo clines over the 53% and 68%, respectively, of their virginianus, northern pygmy-owl Glaucidium gnoma, breeding ranges in the BBS survey area. burrowing owl Athene cunicularia, barred owl Strix Hummingbirds. Order: Apodiformes,Family:Trochilidae, varia, short-eared owl Asio flammeus) Subfamily: Trochilinae (ruby-throated hummingbird Archi- Short-eared owl and burrowing owl are diurnal lochus colubris, black-chinned hummingbird Archilochus and hence are the most observable owl species along alexandri, Anna’s hummingbird Calypte anna,Costa’s BBS routes. Both species have only about 30% of hummingbird Calypte costae, calliope hummingbird their range in the BBS area; Short-eared owls have Stellula calliope, broad-tailed hummingbird Selasphorus fluctuating populations with no significant trend, but platycercus, rufous hummingbird Selasphorus rufus,Allen’s burrowing owls are significantly declining (21.1%/ hummingbird Selasphorus sasin) y). Eastern screech-owl and western screech-owl are These hummingbirds have 83% of their ranges, rarely detected on BBS routes; eastern screech-owl on average, in the BBS area. Among the four has undergone a significant decline (21.4%/y), species surveyed by the BBS that are of conserva- while the western screech-owl has negative but tion concern, two (Rufous hummingbird at 2 2 insignificant trends that are very imprecisely esti- 2.0%/y and Allen’s hummingbird at 4.5%/y) are significantly declining. Among the other species, mated. Northern pygmy-owl is also encountered at only broad-tailed hummingbird is significantly very low abundance on BBS routes and shows a declining (21.7%/y). Ruby-throated hummingbird, nonsignificant positive trend. Barred owl is signifi- the only eastern species, is significantly increasing cantly increasing and has 87% of its range in the (1.9%/y). BBS area. Great horned owl is significantly declining Belted kingfisher. Order: Coraciiformes, Family: Alce- in the 40% of its range in the BBS survey area. dinidae, Subfamily: Cerylinae Nighthawks. Order: Caprimulgiformes,Family:Caprimul- Belted kingfisher Megaceryle alcyon, although not gidae, Subfamily: Chordeilinae (lesser nighthawk Chordeiles presently of conservation concern, has been declin- acutipennis, common nighthawk Chordeiles minor) ing significantly at a rate of 21.6%/y over the BBS Common nighthawk has 75% of its range in the interval. Widespread throughout the eastern, cen- survey area and is significantly declining (22.2%/y). tral, and northwestern portions of the BBS survey Lesser nighthawk, a southwestern species, has only area, 66% of this species’ range is covered by the 27% of its range in the BBS survey area and has very BBS. Declines are quite uniform throughout the imprecisely estimated trends. BBS area; regional analyses indicate that only some Poorwill, Chuck-will’s-widow, and whip-poor-will. Order: portions of the Mississippi Alluvial Valley and Caprimulgiformes, Family: Caprimulgidae, Subfamily: Prairie Potholes have nondecreasing populations. Caprimulginae (common poorwill Phalaenoptilus nuttallii, Woodpeckers. Order: Piciformes,Family:Picidae, Chuck-will’s-widow Caprimulgus carolinensis, eastern Subfamily: Picinae (Lewis’s woodpecker Melanerpes lewis, whip-poor-will Caprimulgus vociferus red-headed woodpecker Melanerpes erythrocephalus,acorn Each of these three nightjars has .75% of woodpecker Melanerpes formicivorus, gila woodpecker breeding range within the BBS survey area. The Melanerpes uropygialis, golden-fronted woodpecker two eastern species, Chuck-will’s-widow and whip- Melanerpes aurifrons, red-bellied woodpecker Melanerpes poor-will, are significantly declining, while common carolinus, Williamson’s sapsucker Sphyrapicus thyroideus, poorwill has no apparent survey-wide trend. Al- yellow-bellied sapsucker, red-naped sapsucker, red- though these species are not active during most of breasted sapsucker, ladder-backed woodpecker Picoides later stops along BBS routes, only the eastern whip- scalaris, Nuttall’s woodpecker Picoides nuttallii,downy poor-will has notably imprecise estimates of popula- woodpecker Picoides pubescens, hairy woodpecker Picoides tion change; that lack of precision is likely due to villosus, red-cockaded woodpecker Picoides borealis,white- imprecise estimates during the early years of the headed woodpecker Picoides albolarvatus,Americanthree- survey. toed woodpecker Picoides dorsalis,black-backed Swifts. Order: Apodiformes, Family: Apodidae, Sub- woodpecker Picoides arcticus, northern flicker Colaptes families: Cypseloidinae, Chaeturinae, and Apodinae (black auratus,gildedflickerColaptes chrysoides, pileated swift Cypseloides niger, chimney swift Chaetura pelagica, woodpecker Dryocopus pileatus) Vaux’s swift Chaetura vauxi, white-throated swift Woodpeckers occupy many regions in North Aeronautes saxatalis) America and vary greatly in their patterns of

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 17 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. population change. Although three species have significantly declining. Four of the other six species #30% of their ranges within the BBS area, on are significantly increasing; populations of great average the woodpeckers have 70% of their ranges crested flycatcher and Cassin’s kingbird appear in the survey area. Seven of the 21 species are stable. These species vary widely in percentage of classified as of conservation concern; four of those range in BBS area, with brown-crested flycatcher species (Lewis’s woodpecker, red-headed woodpeck- and Couch’s kingbird having ,10%, Cassin’s er, red-cockaded woodpecker, and gilded flicker) are kingbird having 35%, and all other species having significantly declining, and two (Nuttall’s woodpeck- .70%. er and white-headed woodpecker) are significantly Loggerhead shrike. Order: Passeriformes, Family: increasing. Among the 14 species that are not Laniidae classified of conservation concern, only golden- Loggerhead shrike Lanius ludovicianus is of conser- fronted woodpecker (a southwestern species) and vation concern and is significantly declining northern flicker are significantly declining. The (23.2%/y) throughout the 85% of its breeding remaining species are stable (N = 8) or increasing range covered by the BBS. (N = 4). Vireos. Order: Passeriformes, Family: Vireonidae (white- Pewees, Empidonax flycatchers, and phoebes. eyed vireo Vireo griseus, Bell’s vireo Vireo bellii, gray Order: Passeriformes, Family: Tyrannidae, Subfamily: vireo Vireo vicinior, yellow-throated vireo Vireo flavifrons, Fluvicolinae (olive-sided flycatcher Contopus cooperi, plumbeous vireo Vireo plumbeus, Cassin’s vireo Vireo western wood-pewee Contopus sordidulus, eastern cassinii, blue-headed vireo Vireo solitarius, Hutton’s wood-pewee Contopus virens, yellow-bellied flycatcher vireo Vireo huttoni, warbling vireo Vireo gilvus, Empidonax flaviventris, Acadian flycatcher Empidonax Philadelphia vireo Vireo philadelphicus, red-eyed vireo virescens, alder flycatcher, willow flycatcher, ‘‘Traill’s’’ Vireo olivaceus) flycatcher, least flycatcher Empidonax minimus, Ham- On average, 79% of the ranges of the 11 vireo mond’s flycatcher Empidonax hammondii, gray fly- species are covered by the BBS. Interestingly, only catcher Empidonax wrightii, dusky flycatcher Empidonax plumbeous vireo is declining (22.7%/y), and most oberholseri, Pacific-slope and Cordilleran flycatchers of this species’ decline occurred prior to 1980. [combined], black phoebe Sayornis nigricans, eastern Populations of the two species of conservation phoebe Sayornis phoebe, Say’s phoebe Sayornis saya, concern (Bell’s vireo and gray vireo) and Philadel- vermilion flycatcher Pyrocephalus rubinus) phia vireo appear stable. The remaining seven With few exceptions, most of the flycatchers in species show significant population increases. this group have large portions of their ranges within Jays and crows. Order: Passeriformes, Family: Corvidae the BBS survey area. The three phoebe species are (gray jay Perisoreus canadensis, green jay Cyanocorax yncas, either stable or increasing, but 9 of the 13 other pinyon jay Gymnorhinus cyanocephalus, Steller’s jay flycatchers and peewee species are declining or have Cyanocitta stelleri, blue jay Cyanocitta cristata, western negative but nonsignificant trend estimates. The two scrub-jay Aphelocoma californica, Clark’s nutcracker species with populations of conservation concern, Nucifraga columbiana, black-billed magpie Pica willow flycatcher (21.6%/y) and olive-sided fly- hudsonia, yellow-billed magpie Pica nuttalli, American catcher (23.5%/y), are both undergoing significant crow Corvus brachyrhynch, northwestern crow Corvus declines. Vermilion flycatcher has ,10% of its caurinus, fish crow Corvus ossifragus, Chihuahuan raven breeding range in the BBS survey area and shows Corvus cryptoleucus, common raven Corvus corax) nonsignificant increases. Declines in aerial insecti- Fourteen species of corvids are surveyed by the vores have been documented from BBS data (Nebel BBS. Among jay and magpie species, four show et al. 2010), although phoebes tend to breed in significant population declines, four appear stable, human-influenced habitats and hence may show and only the green jay (which has limited BBS data) different population trajectories than most other shows a significant increase (8.4%/y). Black-billed aerial insectivores. magpie, blue jay, and two species of conservation Myiarchus flycatchers and kingbirds. Order: Passeriformes, concern (yellow-billed magpie and pinyon jay) show Family: Tyrannidae,Subfamily:Tyranninae (ash-throated significant declines. The five species of crows and flycatcher Myiarchus cinerascens,greatcrestedflycatcher ravens all have positive or stable trends, and the Myiarchus crinitus,brown-crestedflycatcherMyiarchus increases in common raven are significant and tyrannulus,Couch’skingbirdTyrannus couchii, Cassin’s noteworthy (2.5%/y). Most of these corvids are kingbird Tyrannus vociferans,westernkingbirdTyrannus well-adapted to urban and suburban environments. verticalis, eastern kingbird Tyrannus tyrannus, scissor-tailed Exceptions to this pattern include yellow-billed flycatcher Tyrannus forficatus) magpie, pinyon jay, gray jay, and Clark’s nutcrack- The two grassland-breeding species in this group, er, which each prefer forested habitats, and the scissor-tailed flycatcher and eastern kingbird, are aridland Chihuahuan raven. American crow shows both well-surveyed by the BBS (,90% of their recent slight population declines that have been breeding ranges in the survey area) and are associated with exposure to West Nile Virus

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 18 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al.

(LaDeau et al. 2007), although populations have Brown creeper. Order: Passeriformes, Family: Certhiidae, now rebounded to pre-exposure levels. Subfamily: Certhiinae Horned lark. Order: Passeriformes, Family: Alaudidae The brown creeper Certhia americana, a widespread A grassland-breeding species of conservation forest bird having 71% of its range covered by the concern, horned lark Eremophila alpestris has 47% of BBS survey area, has positive but nonsignificant its range in the BBS survey area and is significantly trend estimates. declining (22.4%/y). Wrens. Order: Passeriformes, Family: Troglodytidae Martin and swallows. Order: Passeriformes Family: (cactus wren Campylorhynchus brunneicapillus, rock Hirundinidae Subfamily: Hirundininae (Purple martin wren Salpinctes obsoletus, canyon wren Catherpes Progne subis, tree swallow Tachycineta bicolor, violet- mexicanus, Carolina wren Thryothorus ludovicianus, green swallow Tachycineta thalassina, northern rough- Bewick’s wren Thryomanes bewickii, house wren winged swallow Stelgidopteryx serripennis, bank swallow Troglodytes aedon, winter wren Troglodytes hiemalis, Riparia riparia, cliff swallow Petrochelidon pyrrhonota, Pacific wren Troglodytes pacificus, sedge wren cave swallow Petrochelidon fulva, barn swallow Hirundo Cistothorus platensis, marsh wren Cistothorus palustris) rustica) Of the 10 wren species, three (cactus, Bewick’s, These aerial insectivores also tend to be declining. and Pacific wren) are significantly declining. Only two species, the cave swallow of the southwest Bewick’s wren is of conservation concern due to (24.8%/y) and the widespread cliff swallow (0.4%/y) large population losses in eastern parts of its range; show significant and nonsignificant increases, re- its abundance map is based on recent (post-2000) spectively; all other species show declines, and data and illustrates the absence of recent encoun- significantly so for purple martin, tree swallow, bank ters in most eastern states. Carolina wren and swallow, and barn swallow. winter wren are well-known to be sensitive to Chickadees and titmice. Order: Passeriformes, Family: prolonged snow cover and so, not surprisingly, Paridae (Carolina chickadee Poecile carolinensis, black- show fluctuations relating to severe winters in the capped chickadee Poecile atricapillus, mountain eastern United States. Marsh wrens and house chickadee Poecile gambeli, chestnut-backed chickadee wrens significantly increased in population over the Poecile rufescens, boreal chickadee Poecile hudsonicus, oak BBS time period. titmouse Baeolophus inornatus, juniper titmouse Gnatcatchers. Order: Passeriformes,Family:Sylviidae, Baeolophus ridgwayi, tufted titmouse Baeolophus bicolor) Subfamily: Polioptilinae (blue-gray gnatcatcher Polioptila All of these parids have .70% of their breeding caerulea, black-tailed gnatcatcher Polioptila melanura) ranges in the BBS survey area except for boreal Blue-gray gnatcatcher is increasing (0.6%/y) over chickadee, which only has 27% of its range in the the 75% of its range covered by the BBS. The black- area. Two chickadees with ranges in the western tailed gnatcatcher, which has only 34% of its range United States and Canada (mountain chickadee and surveyed, shows significant declines (22.0%/y) chestnut-backed chickadee) are significantly declin- within the surveyed area. ing, along with oak titmouse, which is also declining American dipper. Order: Passeriformes, Family: and is of conservation concern. Tufted titmouse and Cinclidae black-capped chickadee are significantly increasing. About half of the range of American dipper Cinclus Verdin. Order: Passeriformes, Family: Remizidae mexicanus is covered by the BBS, and no trend is The verdin Auriparus flaviceps, a southwestern species evident in the 213 survey routes on which the species that has only 42% of its range in the BBS survey area, is encountered. is significantly declining at a rate of 22.7%/y. Kinglets. Order: Passeriformes, Family: Regulidae Bushtit. Order: Passeriformes, Family: Aegithalidae (golden-crowned kinglet Regulus satrapa, ruby- Less than half of the breeding range of bushtit crowned kinglet Regulus calendula) Psaltriparus minimus falls into the BBS survey area; Both kinglet species have about half of their BBS results show no significant trend overall. breeding ranges in the BBS survey area. Golden- Nuthatches. Order: Passeriformes,Family:Sittidae,Sub- crowned kinglets have significant declines survey- family: Sittinae (red-breasted nuthatch Sitta canadensis, wide; ruby-crowned kinglet shows no significant white-breasted nuthatch Sitta carolinensis,pygmynuth- trend. atch Sitta pygmaea, brown-headed nuthatch Sitta pusilla) Wrentit. Order: Passeriformes, Family: Sylviidae The four species of nuthatches all have .70% of Over 90% of wrentit Chamaea fasciata range occurs their range in the BBS survey area. Brown-headed in the BBS survey area, and this species of nuthatch, which breeds in the southeastern United conservation interest shows significantly (20.7%/y) States, is of conservation concern due to declining declining populations. populations, although the present BBS results have Bluebirds and thrushes. Order: Passeriformes, Family: CIs that overlap 0. BBS data indicate that white- Turdidae (eastern bluebird Sialia sialis, western breasted nuthatch and red-breasted nuthatch are bluebird Sialia mexicana, mountain bluebird Sialia significantly increasing. currucoides, Townsend’s solitaire Myadestes townsendi,

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 19 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. veery Catharus fuscescens, Swainson’s thrush Catharus Longspurs. Order: Passeriformes,Family:Calcariidae ustulatus, hermit thrush Catharus guttatus, wood thrush (chestnut-collared longspur Calcarius ornatus,McCown’s Hylocichla mustelina, American robin Turdus migratorius, longspur Rhynchophanes mccownii) varied thrush Ixoreus naevius) Both longspur species have breeding ranges in the Turdid thrushes primarily live in forested biomes, northern plains that are completely covered by the although American robins and wood thrush are BBS, and they are grassland obligate species of often associated with human-dominated habitats. conservation concern. Both species are significantly On average, 69% of their ranges are covered by the declining, chestnut-collared longspur at 24.3%/y BBS. Varied thrush (33% of range surveyed by the and McCown’s longspur at 25.3%/y. BBS) and wood thrush (100%) are species of Wood warblers. Order: Passeriformes Family: Parulidae conservation interest, and BBS data indicate that (ovenbird Seiurus aurocapillus, worm-eating warbler both species are declining in population size. Veery, Helmitheros vermivorus, Louisiana waterthrush Parkesia Swainson’s thrush, and mountain bluebird are also motacilla, northern waterthrush Parkesia noveboracensis, significantly declining. Populations of eastern blue- golden-winged warbler Vermivora chrysoptera, blue- bird and American robin are significantly increasing. winged warbler Vermivora cyanoptera, black-and-white Mimic thrushes. Order: Passeriformes, Family: Mimidae warbler Mniotilta varia, prothonotary warbler (gray catbird Dumetella carolinensis, northern Protonotaria citrea, Swainson’s warbler Limnothlypis mockingbird Mimus polyglottos, sage thrasher swainsonii, Tennessee warbler Oreothlypis peregrina, Oreoscoptes montanus, brown thrasher Toxostoma rufum, orange-crowned warbler Vermivora celata, Lucy’s long-billed thrasher Toxostoma longirostre, Bendire’s warbler Oreothlypis luciae, Nashville warbler Vermivora thrasher Toxostoma bendirei, curve-billed thrasher ruficapilla, Virginia’s warbler Oreothlypis virginiae, Toxostoma curvirostre, California thrasher Toxostoma Connecticut warbler Oporornis agilis, MacGillivray’s redivivum, crissal thrasher Toxostoma crissale,Le warbler Oporornis tolmiei, mourning warbler Oporornis Conte’s thrasher Toxostoma lecontei) philadelphia, Kentucky warbler Oporornis formosus, Of the 10 mimic thrushes encountered on the common yellowthroat Geothlypis trichas, hooded BBS, six have significantly declining populations. warbler Wilsonia citrina, American redstart Setophaga Only long-billed thrasher, a species for which the BBS ruticilla, Cape May warbler Setophaga tigrina, cerulean covers only 32% of its range via 38 survey routes in warbler Setophaga cerulea, northern parula Parula southern Texas, has significantly increasing popula- americana, magnolia warbler Setophaga magnolia, bay- tions. The three species of conservation interest breasted warbler Setophaga castanea, blackburnian (Bendire’s thrasher, California thrasher, Le Conte’s warbler Setophaga fusca, yellow warbler Setophaga thrasher) are all significantly declining. The BBS petechia, chestnut-sided warbler Setophaga pensylvanica, surveys .80% of the ranges of seven of the mimic blackpoll warbler Setophaga striata, black-throated thrushes, but three species (long-billed thrasher, blue warbler Setophaga caerulescens, palm warbler curve-billed thrasher, crissal thrasher) have #40% Setophaga palmarum, pine warbler Setophaga pinus, of their breeding range in the BBS survey area. yellow-rumped warbler Setophaga coronata, yellow- European starling. Order: Passeriformes,Family:Sturnidae throated warbler Setophaga dominica, prairie warbler The introduced European starling Sturnus vulgaris Setophaga discolor, Grace’s warbler Setophaga graciae, has 70% of its breeding range in the BBS survey area black-throated gray warbler Setophaga nigrescens, and is significantly declining (21.4%/y). Townsend’s warbler Setophaga townsendi, hermit Sprague’s pipit. Order: Passeriformes,Family:Motacillidae warbler Setophaga occidentalis, black-throated green Sprague’s pipit Anthus spragueii is a grassland warbler Setophaga virens, Canada warbler Cardellina species of conservation concern whose range is canadensis, Wilson’s warbler Cardellina pusilla, yellow- completely covered by the BBS. The species is breasted chat Icteria virens) significantly decreasing at a rate of 23.5%/y. Most of the 44 parulid warblers surveyed by the Cedar waxwing. Order: Passeriformes Family: Bombycillidae BBS have the bulk of their ranges within the BBS Cedar waxwing Bombycilla cedrorum is surveyed survey area, although blackpoll warbler only has over 84% of its range by the BBS and shows a 17% of its range in the region. Except for the habitat positive trend that is significant for regression generalist common yellowthroat and the aridland- method results but is not for the interval results. A breeding Lucy’s warbler, all species inhabit forest preponderance of states and provinces have increas- habitats. Populations of 17 warbler species are ing populations, and increases are particularly significantly declining, and populations of only six prevalent in the southern portions of the range. species are significantly increasing. Fourteen species Phainopepla. Order: Passeriformes,Family:Ptilogonatidae are of management concern, including seven with The phainopepla Phainopepla nitens breeds primar- significant declines (prothonotary warbler, golden- ily in Mexico, and only 37% of its range occurs in winged warbler, cerulean warbler, Grace’s warbler, the BBS survey area. BBS results indicate a stable prairie warbler, Kentucky warbler, Canada warbler). population. All of these species except Canada warbler (which is

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 20 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. also found in other forest biomes) have their entire Piranga flava, summer tanager Piranga rubra,scarlet ranges in eastern forest habitats and within the BBS tanager Piranga olivacea, western tanager Piranga survey area. Nonsignificant negative trends occur in ludoviciana,northerncardinalCardinalis cardinalis, four species of conservation concern (bay-breasted pyrrhuloxia Cardinalis sinuatus, rose-breasted grosbeak warbler, blue-winged warbler, Virginia’s warbler, Pheucticus ludovicianus, black-headed grosbeak Pheucticus and hermit warbler), and populations of the other melanocephalus,bluegrosbeakPasserina caerulea,lazuli species of conservation concern appear to be stable bunting Passerina amoena, indigo bunting Passerina cyanea, (Lucy’s warbler, Swainson’s warbler, and worm- painted bunting Passerina ciris, dickcissel Spiza americana) eating warbler). Most species in this group breed in forested New World sparrows. Order: Passeriformes, Family: habitats, albeit often in gaps or successional areas. Emberizidae (olive sparrow Arremonops rufivirgatus, Exceptions include the grassland-breeding dickcissel, green-tailed towhee Pipilo chlorurus, spotted towhee which is a species of conservation concern that the Pipilo maculatus, eastern towhee Pipilo erythrophthalmus, BBS indicates to be declining. Similarly, the arid- rufous-crowned sparrow Aimophila ruficeps, canyon land-breeding pyrrhuloxia is also declining (regres- towhee Melozone fusca, California towhee Melozone sion results). The eastern-breeding rose-breasted crissalis, Abert’s towhee Pipilo aberti, Cassin’s sparrow grosbeak shows population declines, while the Peucaea cassinii, Bachman’s sparrow Peucaea aestivalis, western black-headed grosbeak is increasing. Indigo chipping sparrow Spizella passerina, clay-colored bunting is significantly declining while painted sparrow Spizella pallida, Brewer’s sparrow Spizella bunting (a species of conservation concern) and breweri, field sparrow Spizella pusilla, black-chinned lazuli bunting show negative but nonsignificant sparrow Spizella atrogularis, vesper sparrow Pooecetes trends. Amongst the tanagers, western tanager and gramineus, lark sparrow Chondestes grammacus, black- summer tanager are significantly increasing; Scarlet throated sparrow Amphispiza bilineata, sage sparrow tanager shows insignificant trends. Northern cardi- Amphispiza belli, lark bunting Calamospiza melanocorys, nal, which is often associated with human commu- savannah sparrow Passerculus sandwichensis, grasshopper nities, is significantly increasing. sparrow Ammodramus savannarum, Baird’s sparrow New World blackbirds. Order: Passeriformes,Family: Ammodramus bairdii, Henslow’s sparrow Ammodramus Icteridae (bobolink Dolichonyx oryzivorus,red-winged henslowii, Le Conte’s sparrow Ammodramus leconteii, blackbird Agelaius phoeniceus, tricolored blackbird Agelaius Nelson’s sparrow Ammodramus nelsoni, seaside sparrow tricolor, eastern meadowlark Sturnella magna,western Ammodramus maritimus, fox sparrow Passerella iliaca,song meadowlark Sturnella neglecta, yellow-headed blackbird sparrow Melospiza melodia, Lincoln’s sparrow Melospiza Xanthocephalus xanthocephalus, rusty blackbird Euphagus lincolnii, swamp sparrow Melospiza georgiana,white- carolinus, Brewer’s blackbird Euphagus cyanocephalus, throated sparrow Zonotrichia albicollis, white-crowned common grackle Quiscalus quiscula, boat-tailed grackle sparrow Zonotrichia leucophrys, dark-eyed junco Junco Quiscalus major, great-tailed grackle Quiscalus mexicanus, hyemalis) bronzed cowbird Molothrus aeneus,brown-headed The New World sparrows include many scrub- cowbird Molothrus ater, orchard oriole Icterus spurius, successional, aridland, and grassland breeding spe- hooded oriole Icterus cucullatus, Bullock’s oriole Icterus cies known to be declining. The only species showing bullockii, Baltimore oriole Icterus galbula, Scott’s oriole a significant increase (3.1%/y) is olive sparrow, for Icterus parisorum) which the BBS covers only 6% of its range. Of the BBS results indicate that most blackbirds are 34 species in the group, 17 have significant declines, declining; only 1 of the 18 species (great-tailed but 27 have negative estimates of trend. The grackle) is significantly increasing but 11 species are geographic and temporal extent of declines in the significantly declining. The limited BBS data for group has stimulated a discussion of the role of rusty blackbird (only 27% of the breeding range is in habitats in conservation (U.S. NABCI Committee the BBS survey area) corroborate declines docu- 2009). The BBS provides the primary source of mented from Christmas Bird Counts (Niven et al. population information for 13 of the group’s 2004). Grassland-breeding species such as meadow- conservation concern species. Of these, five have larks and bobolink have well-documented declines significantly declining populations. Two species of (Peterjohn and Sauer 1999). Orioles with northern conservation concern have noteworthy patterns of distributions show significant declines; southwestern population change. Henslow’s sparrow has had species (hooded and Scott’s orioles) do not show increasing populations in recent years, and its significant population changes. Tricolored black- nonsignificant decline reflects these recent increases. bird, which is a species of conservation concern, Baird’s sparrow experienced significant declines shows positive but nonsignificant population chang- (23.0%/y), but populations appear to have experi- es. The large but highly variable counts of tricolored enced more stability in recent years. blackbird make estimation of site effects very Tanagers, cardinals, grosbeaks, and buntings. Order: imprecise, and these large variances are reflected Passeriformes,Family:Cardinalidae (hepatic tanager in the inflated indexes for this species. Other

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 21 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. blackbirds and grackles (except for great-tailed area. For the obligate species, on average 42% of grackle) are declining. Brown-headed cowbird is their breeding ranges are in the BBS survey area. declining, and the 10% of the bronzed cowbird’s Overall, obligate boreal forest birds show a range covered by the BBS shows no trend for that nonsignificant 7.5% decline over the interval. Fifty- species. four percent (42, 71) of the species have negative Finches, crossbills, and grosbeaks. Order: Passeriformes, trend estimates. Family: Fringillidae, Subfamily: Carduelinae (pine Eastern forest birds. The 111 eastern forest species grosbeak Pinicola enucleator, purple finch Carpodacus form a very heterogeneous group occurring in 10 purpureus, Cassin’s finch Carpodacus cassinii, house BCRs. However, the 25 obligate species have finch Carpodacus mexicanus, red crossbill Loxia significantly declined over the interval by 24%. curvirostra, white-winged crossbill Loxia leucoptera, These declines reflect the presence of early pine siskin Carduelis pinus, lesser goldfinch Carduelis successional species, along with several declining psaltria, Lawrence’s goldfinch Carduelis lawrencei, neotropical migrant species. The Bayesian estimate American goldfinch Spinus tristis, evening grosbeak of percentage of species with negative trend Coccothraustes vespertinus) estimates is 68% (60, 76). Most of these species show significant declines. Subtropical forest birds. This small collection of 15 Lawrence’s goldfinch is the only species of conser- species that occur in Texas and Florida contains vation concern in this group, and BBS results suggest several widespread species with rapidly increasing a nonsignificant decline for its population. Purple populations. Almost all populations in this group are finch and Cassin’s finch are significantly declining, increasing, possibly due to northward expansion of and house finch, although it had dramatically ranges from regions south of the BBS survey area. increased subsequent to its introduction in New The Bayesian estimate of percentage of species with York during the 1940s, has recently experienced negative trend estimates is 13% (6, 20). declines related to a pathogenic mycoplasma Western forest birds. There are 114 species of western bacterium (Hochachka and Dhondt 2000). Pine forest birds, and 37 obligate species. The species grosbeak, evening grosbeak, and the two crossbills show no consistent population changes over the have very imprecise results from the BBS, although 1968–2011 period. both grosbeak species show significant declines. Wetland birds. These 103 species rely on wetlands in Weaver finches. Order: Passeriformes, Family: some way, and form a heterogeneous group. The Passeridae (house sparrow Passer domesticus, Eurasian composite long-term change for the collection of tree sparrow Passer montanus) species is a nonsignificant 21.4%. The Bayesian Both these species were introduced to North estimate of percentage of species with negative trend America. BBS indicates significant declines in the estimates is 48% (40, 54). very widespread house sparrow but significant Marsh birds. These 29 species are obligate to increases in the very local Eurasian tree sparrow. wetlands with emergent vegetation. Many of them are poorly surveyed by the BBS, and the composite Summary of ‘‘State of the Birds’’ and long-term change for the collection of species is a other species group results nonsignificant 21.5%. The Bayesian estimate of Summary information for the species groups are percentage of species with negative trend estimates is presented in Appendix B. 55% (34, 72). Aridland birds. The 61 species of aridland birds Generalists. These 65 species occur in more than summarized in BBS analyses inhabit desert and three primary habitats but have a wide variety of life- Great Basin regions in the western and southwestern histories, hence the group has little meaning aside United States. The 17 obligate species show a from the notion of broad habitat usage. In composite, composite total decline of 39.7% over the interval they have been increasing between 1968 and 2011 by 1968–2011. The Bayesian estimate of percentage of an imprecisely estimated but significant 32.2%. The species with negative trend estimates is 88% (95% Bayesian estimate of percentage of species with CI: 71, 100). negative trend estimates is 49% (43, 55). Grassland birds. Grassland birds, both the 41 total Urban/suburban birds. The 117 species in this group species and the 24 obligates monitored by the BBS, are able to coexist with human populations. Within have been showing consistent declines throughout this heterogeneous group, populations have been the BBS interval. Obligate species have declined in increasing (a composite estimate of change of composite 37.8% between 1968 and 2011; 75% (63, 18.3%), but that estimate is imprecise and its 83) of the obligate species had negative trend credible interval overlaps 0. The Bayesian estimate estimates. of percentage of species with negative trend Boreal forest birds. These 80 species and 24 obligate estimates is 46% (50, 56). species live primarily in six northern BCRs, and Exotic birds. These eight species were introduced much of their ranges are north of the BBS survey into North America, and several species are now

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 22 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. among the most abundant bird species on the of population change. Although interpretation of the continent. This group shows a composite metric often assumes that the number represents nonsignificant increase of 15% during the survey both consistent change within the interval and a interval, with the large variation in the composite prediction of future change, for many species this change reflecting heterogeneity in change among the assumption is not true. For example, trends species in the group. Four of the species have computed over the interval 2001–2011 are often undergone significant declines over the interval, and not consistent with the 1966–2011 trends; only 14% only Eurasian tree sparrow is significantly of species showed significant declines (27% showed increasing. The Bayesian estimate of percentage significant increases) in the most recent decade. of species with negative trend estimates is 63% (50, Examination of population change estimates by state 75). or province, or by BCR within species, documents Neotropical migrant birds. The 133 species of further complexity in population change inherent neotropical migrant birds show a decline of within bird species. Of course, there are species for 210.5% over the 1968–2011 interval, although the which change does appear consistent over space and 95% CI overlaps 0. The Bayesian estimate of time. Most species, however, are not consistently percentage of species with negative trend estimates declining or increasing among regions, and we is 60% (55, 65). encourage readers to examine the species accounts Temperate migrant birds. The 181 species of to have a better context for evaluating change. temperate migrant birds show a nonsignificant Grouping species by common characteristics such change of 24.1% over the 1968–2011 interval. as migration status (e.g., neotropical migrant birds; The Bayesian estimate of percentage of species with Robbins et al. 1989) or habitat affinities (e.g., negative trend estimates is 56% (51, 60). grassland breeding birds; Peterjohn and Sauer Permanent resident birds. The 95 species of per- 1999) has proven to be a powerful means of manent resident birds show a composite non- synthesis of BBS results. Grassland- and aridland- significant increase of 12.1% over the 1968–2011 breeding birds are well-known to be declining, interval. The Bayesian estimate of percentage of primary based on BBS analyses (U.S. NABCI species with negative trend estimates is 49% (44, Committee 2009). Indications of declines in neo- 56). tropical migrant birds (Robbins et al. 1989) were an important motivating force for establishment of Discussion Partners in Flight (Rich et al. 2004). As with individual species data, temporal patterns occur in Population change in North composite trends for the species groups, and our American birds group summaries allow readers to examine the The BBS covers most of North America and temporal patterns in the composite index to better provides data for a diverse collection of bird species. interpret these group summary results. One issue Users of the data have long been challenged by the that remains to be explored is spatial variation in need to present summary results from the BBS in a group summaries, and we have developed (but not way that adequately conveys the uncertainty associ- yet implemented) methods for regional group ated with the temporal and geographic scope of the summaries that accommodate regional differences survey. In this report, we have attempted to present in species pools. information about population change with an Neotropical migrant bird results provide a case appropriate context for interpreting the results, study for the need to consider all of these issues in allowing readers to evaluate the relevance of the group summary analyses. Robbins et al. (1989) long-term trend estimate in the context of temporal documented temporal patterns in population change and spatial variation in the species’ population. of neotropical migrant birds in the eastern part of Simple summaries of these data are inevitably the continent (Robbins et al. 1989). This widely cited misleading; metrics of change must be carefully paper motivated a great deal of public concern for defined to provide appropriate context. migrants. However, Sauer and Droege (1992) Interval-specific estimates of change provide a documented regional variation in declines of neo- starting point for interpretation of survey results. tropical migrant birds; western species were gener- Our analysis shows that 57% of the 426 North ally increasing in population while eastern species American bird species we analyzed experienced were declining. The decades of additional data since significant changes over the 1966–2011 interval, those initial results indicate that declines in popula- with 36% of species experiencing significant declines tion have not continued even in the eastern United and 21% of species significantly increasing over the States. These inconsistencies in time and space of interval. These very general summaries, although population change in neotropical migrant birds often cited and used to motivate conservation highlight the need for caution in interpretation of activities, do not adequately reflect the complexity BBS results.

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Use of BBS data to evaluate why bird stressors; and 2) by using alternative models directly populations are changing in adaptive management, in which monitoring is Documenting patterns of population change from paired with management to both assess the conse- BBS data generally does not provide insights into quences of management and improve our models of why populations are changing. Historically, docu- why bird populations change. menting patterns of population change was viewed as sufficient information for managers. Identification Issues in the analysis of BBS data of consistent declines among groups of species has In the species accounts, we focus on presentation been an important component of bird conservation, of quantitative results and identification of possible in which monitoring data has been used to identify concerns associated with the analysis. Sauer et al. declining species, after which conservation focuses (2003) defined deficiencies in the analysis of change on searching for causes of declines by identifying associated with 1) limited data, due to either very species- or group-specific factors influencing the small sample sizes or limited survey information population. This ‘‘declining population paradigm’’ from the species’ range; 2) low counts of some species (Caughley 1994) has been used to focus conservation on BBS routes; 3) imprecise results, indicating efforts on grassland and aridland birds, and declines poor ability to evaluate population change; and 4) documented from BBS data provided a strong inconsistency in estimates of change over time (e.g., rationale for conservation efforts for those species. www.mbr-pwrc.usgs.gov/bbs/cred.html). Sauer et al. This paradigm is still prevalent in bird conservation, (2003) summarized the frequency of these deficiencies as shown by the conservation interest in aerial for several groups of species. In the species accounts, insectivore species after declines were documented we indicate when limited data and imprecise results in BBS data (e.g., Nebel et al. 2010). occur in the hierarchical model analysis. However, the BBS is used in a large variety of Species and range coverage. Over 900 species of birds scientific studies of factors influencing population have been observed in North America north of change in birds. Nichols et al. (2012) notes that Mexico (Birdwatching.com 1998). Over 500 of these observation of patterns in survey results leads to species are encountered on BBS survey routes. Of weak inference, but that development of a priori these, we summarized population change for 426 hypotheses about factors influencing population species. The remaining species are generally change and testing them using survey data lead to represented by small numbers of observations and stronger inference. BBS data are frequently used in have ranges largely outside the BBS-surveyed area. this way (e.g., LaDeau et al. 2007), and it is often Even among species for which we conduct trend convenient to formulate these alternative hypotheses analysis, the percentage of the species’ range that is in terms of covariates that may correlate with monitored can vary from virtually 0 (e.g., great black- population change. Using this approach, the BBS backed gull) to 100 (e.g., sage grouse). On average, the has proven effective in providing quantitative surveyed area covers 66% of ranges of species for assessments of the effects of environmental stressors which we estimate population change using BBS data. on birds. Climate change is likely to increase the This percentage varies among the indicator groups, frequency of severe storms and other weather events, with grassland-obligate species having an average of and analysis of BBS data has allowed us to begin the 86% of their ranges in the surveyed area but boreal- study of these effects on regional population change forest obligate species having an average of 43%. (Butler 2000). Severe winters influence bird popula- Incomplete coverage of species’ ranges has tions, and using BBS data we now directly model consequences for the interpretation of the survey change in bird populations as a function of winter because no information exists on how population severity (Sauer et al. 1996; Link and Sauer 2007). change in the surveyed area relates to the population For resident and short-distance migrant species such change of the entire population. as Carolina wren and eastern bluebird, severe Concerns about incomplete range coverage are winters had long been known to have negative sometimes mitigated by focusing on regional esti- effects on their local populations; BBS data allow us mates of change. Most jurisdictions (e.g., states) have to quantify these effects at a regional scale and to an interest in population status within their bound- evaluate differential effects on species (Link and aries, and the BBS can provide estimates of Sauer 2007). population change for many regions. However, Hierarchical models described in this monograph without an understanding of change at the scale of can be easily modified to accommodate covariates, species’ ranges, it is difficult to assess the importance and we can use alternative models to more fully of changes at local and regional scales. For example, integrate BBS analyses into the process of under- one of the challenges of BBS analysis is keeping track standing why bird populations are changing via two of species whose ranges are expanding into the approaches: 1) by using direct covariate analyses to surveyed area. Tropical species such as crested assess the importance of possible environmental caracara that historically bred in limited numbers in

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 24 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. the surveyed area have been expanding northward. survey. This is a consequence of the limited data This component of BBS analysis is often neglected in available in the early years of the survey; the BBS discussions of the quality of survey data, but as the did not begin in the central United States until 1967 potential for climate change to affect bird popula- and in the western United States until 1968, and tions increases, population change in peripheral coverage in terms of number of routes surveyed has portions of species’ ranges may play increasingly increased steadily throughout the survey period larger roles in the dynamics of the species. The (Sauer and Link 2010). For many species, precision documentation of portion of current ranges surveyed of annual indexes has increased over time as shown by the BBS presented here is an important first step by decreases in width of CIs. However, population in defining these areas, and provides a context for changes for a variety of species are consistently interpreting species’ trends. The BBS survey area estimated imprecisely from BBS data. Species such and bird ranges will likely change in the future, and as eared grebe have indexes with large credible understanding the dynamics of both will be critical intervals for all years. The CIs form an important for appropriate interpretation of BBS data. additional source of information for BBS analyses Precision of estimates. One issue of particular relevance and make users of BBS data much more aware of for interpreting results from the hierarchical model the limited value of results for some imprecisely analysis is precision. The hierarchical model analyses estimated species (Sauer and Link 2011). We agree clearly show the lack of precision in estimates of trend with their observations; indexes presented without and annual indexes for many species. In particular, CIs in earlier analyses led users to overestimate the many regions had limited samples in the early years of quality of the results. the survey; hence indexes from those earlier years have Relative abundance. It is well known that counts of large credible intervals. This was not evident in earlier birds along BBS routes are underestimates of the analysis, and the estimating equations analysis, which actual numbers of birds present and that these does not control for limited data in early years, often indexes are influenced by a variety of environmental provided misleading views of change for species with factors, which complicate any use of BBS data as limited data in early (or later) years (Link and Sauer estimates of population size (Thogmartin et al. 2002; Sauer and Link 2011). Imprecise estimates have 2006). Simplistic summaries of the data such as always been an issue for the BBS; hierarchical model route regression relied on scaling of annual indexes analyses provide users with appropriate information for presentation so that midyear of the indexes was regarding precision of indexes and trends over time. an average of mean counts on survey routes. For Sauer and Link (2011) used half-widths of 95% many species, this had the desirable effect of CIs to assess the precision of interval trend estimates presenting indexes at a level associated with the from BBS data. Using results from 1966 to 2009, mean counts. However, for species with extreme or and following the cut points for precision described imprecise estimates of change, this scaling resulted in by Sauer et al. (2003), they found that 68 species unrealistically large abundances in extreme years. (16%) had 95% CIs that would not detect a 3%/y The hierarchical model offers an improved scaling of population change, and 25 species (6%) had 95% indexes, as species-abundance is defined in the CIs that would not detect a 5%/y population context of the model, and these model-based change. Thus, the majority of long-term trend estimates control for route and observer effects in estimates meet minimum standards for precision the summary. However, because the model is log- (Sauer et al. 2003). As noted in Sauer et al. (2003), linear, the results need to be transformed to a linear any such standard for precision is arbitrary unless scale, and this transformation requires addition of 2 2 explicitly tied to a predicted change associated with a variance components (0.5s v + 0.5s e) when management objective or to some other significant computing indexes ni,t. For most species, ni,t is population objective. However, these values are similar to the historical weighted mean counts used useful as measures of precision consistent with earlier to scale annual indexes, but for a few species the analyses. addition of these variance components leads to One of the advantages of hierarchical models used annual indexes that are larger than the mean counts in our analysis is that the precision of annual indexes (Sauer and Link 2011). The issue of scaling annual can be readily calculated using MCMC. Earlier indexes and the concerns among users when model- analyses, generally presented without credible inter- based estimates of abundance scale differently from vals, often conveyed a false impression of reliability. simple averages of route counts reflect the complexity Providing credible intervals clearly shows some that arises when sophisticated models are applied to systematic patterns of imprecision related to the the diversity of datasets produced by the BBS. It is history and logistical constraints of the survey. The well known that simple estimates of abundance are most obvious of these patterns is that population biased, but users often develop intuition for results time series for many species show extremely based on observation of the simple estimates. Model- imprecise annual indexes for the first years of the based estimates of abundance occasionally produce

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 25 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. results that conflict with this intuition, and these address these concerns. Two primary criticisms of challenges to intuition are useful because they cause the BBS relate to roadside sampling issues and point- us to consider both the validity of the model structure count limitations, and in the following sections we and the deficiencies of simple summaries. In the case briefly describe these issues and ongoing efforts to of the abundance indexes, values that exceed the mitigate the concerns. naı¨ve estimates of abundance indicate that the model Roadside sampling concerns. Bird populations along is producing large variances among sites, suggesting roadsides differ from nonroadside locations in that users should be cautious in any inference based abundance, and habitats may be changing at on the abundances. different rates along roadsides than in adjacent off- The BBS and endangered species. Endangered species road habitat, raising the concern that estimates of have strict legal requirements for monitoring, and both population size and population change based BBS data are often requested to inform both the on roadside surveys may not be representative of the consideration of species for threatened or nonroadside population. This concern was raised endangered status and to provide information on during review of initial designs for the BBS, but at status for species presently endangered. However, the time the logistical advantages of a purely the BBS was specifically designed as a monitoring roadside design outweighed needs for additional program for widespread and relatively abundant sampling of roadside habitats. Roadside-survey species, and the design is not well suited for rare or issues have been an ongoing topic of discussion difficult-to-detect species. Consequently, the BBS among survey coordinators because roadsides have can contribute to status assessments for relatively direct as well as indirect influences on counting widespread species such as cerulean warbler and (Griffith et al. 2010). Low counts of marsh and mountain plover, but of the species of North wetland birds have historically been thought to American birds known to be endangered, provide evidence of underrepresentation of their threatened, or declining, many have very restricted primary habitats along roadsides, and a variety of distributions, habitats, or life history traits that make on- versus off-road studies have found varying results the BBS a poor survey for them. Of the 74 listed regarding differences in bird abundance, depending species (U.S. NABCI Committee 2009), the BBS on species and habitats considered (e.g., Hutto et al. provides no results for 71 and imprecise results for 1995; Keller and Fuller 1995). We conducted on- three species: wood stork, least tern, and red- and off-road BBS-style counts in Delaware, cockaded woodpecker. The BBS also provides Maryland, Pennsylvania, Virginia, and West information for several species that contain listed Virginia in June 2000 to evaluate the feasibility of subspecies, although in general no useful data exist conducting off-road surveys. We found that for the listed subspecies. differences occurred between on- and off-road estimate of total abundance of warblers and Addressing concerns about the sparrows (estimated collectively). On- and off-road credibility of the BBS as a source of differences also occurred in individual species results. information regarding bird For example, for red-eyed vireos total abundance population change was 74.0 (95% Confidence interval 50.63–97.37) on Presenting analysis results from the BBS requires 50 roadside counts, 126.3 (96.00–156.59) on 50 off- confidence in the credibility of the results. We view road counts. our analyses as controlling for known sources of bias Often, differences between on- and off-road in estimation, and thus providing reasonable esti- abundances and trends are inferred from differences mates of population change. As with all surveys, we in amounts of habitats and rates of change in feel that the BBS methods and analyses should habitats. Interpreted aerial photographs have been always be open to modification due to results of used to assess roadside and off-road habitat ongoing research and statistical developments that differences and relative rates of change in habitats could provide less-biased and/or more precise over time, with indications that forested habitats estimates. For the BBS, this scrutiny is particularly may be underrepresented and urban habitats tend to important because the design of the BBS has been a be more frequent along roadsides (Bart et al. 1995; target of criticism from the start of the program (D. Keller and Scallan 1999). Interpreted Landsat R. Anderson, USGS, personal communication.). information can be used to evaluate amounts of Aside from issues of coverage and precision habitat along and away from roadsides at a regional described earlier, concerns about inherent flaws in scale. Veech et al. (2012) found that habitats along the survey methods still exist. These issues have been BBS routes were representative of regional habitats the topic of extensive research but are still at the scale of BCRs, but that at local scales lightly controversial among users and analysts of BBS data. developed open space habitats were overrepresent- The BBS Strategic Plan (U.S. Geological Survey ed. Hannan (2009) used the Land Cover Trends 2007) sets explicit research goals to evaluate and Study (Loveland et al. 2002) to evaluate whether

North American Fauna | www.fwspubs.org December 2013 | Number 79 | 26 The North American Breeding Bird Survey 1966–2011 J.R. Sauer et al. consistent differential changes occurred in habitats ly, alternative analytical approaches that provide on- vs. off-roads between 1973 and 2000. He found model-based estimates of detection probability may little overall differential change in habitats, although provide some opportunities for direct estimation of consistent differences did exist in rates of change detection in the context of estimation of population between subperiods within the larger interval change (Dail and Madsen 2011). (Hannan 2009). Detection probability concerns. Point counts are well Statistical analysis methods known to provide biased estimates of population Hierarchical models are a natural approach for size, leading Link and Sauer (1998:261) to make the the analysis of BBS data. BBS data are multiscale, observation that ‘‘BBS sampling cannot guarantee and these models provide sufficient flexibility to either a census or a known fixed area of sampling.’’ permit inference at scales from individual points The general strategy for analysis of BBS data has to continental. Implementation of the models in been to add covariates and structure to the analysis Bayesian analyses provides for the first time a to model and control for factors known to influence framework in which the deficiencies of the survey detection of birds along survey routes. The primary design can be accommodated during the analysis. factor known to influence detectability and influence The framework allows for many alternative param- trend is variation among and within observers, and eterizations of the model and allows us to extend the the hierarchical model presently used for BBS modeling to consider covariates that influence both analysis controls for both observer differences and abundance and trend, tying the analysis more closely start-up effects. Ongoing research is directed at both to scientific study of factors influencing bird identifying and modeling other features that populations and to models that can directly be used influence detection of birds and may be influencing to predict the consequences of management activ- our estimation of population change. Recent ities. This linkage to management through habitat analyses have evaluated the need for additional and other covariates in critical to enhancing the controls for traffic disturbance (Griffith et al. 2010) relevance of the BBS as a component of manage- and for changes in phenology effects by ment. incorporating year day as a covariate in the Any generic approach to the analysis of many analysis. Changes in road noise due to traffic species in a complicated dataset is prone to effects have likely not influenced our estimates of limitations. For some species, there are insufficient population change (Griffith et al. 2010). Changes in data to allow inference for at least some strata, and phenology have significantly affected the estimates of this lack of information contributes to poor conver- trend for only three species, and for those species the gence and very imprecise estimates. We screened the differences were in magnitude, not in direction (J. R. results and eliminated these regions from summary Sauer, unpublished data). analyses of states and BCRs in the species accounts; Field methods associated with procedures such as identification and accommodation of these regions multiple observer counts (Nichols et al. 2000; Riddle in the analysis, by elimination or through aggrega- et al. 2010) or distance sampling (Rivera-Milan et al. tion with adjacent regions, is a necessary component 2003) are candidate modifications of the traditional of any BBS analysis. point count to permit direct estimation of detection Another complication relates to the subtle inter- rates in BBS analyses. In the past, concerns about play between the structure of the model and our additional time, analytical needs, and burdens on the ability to estimate model components. The model volunteer observers associated with these methods we used has a trend estimated in the context of have precluded their implementation in BBS random-effect year effects. Alternative parameteri- sampling. However, a larger suite of methods is zations of year effects could include year effects as now available than could have been employed when random effects without a trend, year effects as fixed the BBS was started, computer advances have effects, or year effects as change from prior years revolutionized data management, and modern (Pannekoek and van Strien 2005). Although similar analytical methods can incorporate these approaches quantities are estimated with these parameteriza- by adding additional components to the hierarchical tions, in practice the results can be quite different model described above (e.g., Ke´ry et al. 2009). when they are applied to the same dataset. Because Although it is not yet clear whether any of the the BBS has been unevenly implemented over time, approaches presently under consideration will yield some regions have no data or very limited data in a viable BBS protocol to replace the standard point the early years of the survey. Year effect parame- count, the recent BBS review has motivated field terizations can vary greatly in how they accommo- trials of several approaches to detectability estima- date this limited data; simple random effects or fixed tion to advance our understanding of the methods effect models can be extremely imprecise or can (e.g., Riddle et al. 2010; D. Twedt, USGS Patuxent shrink the estimated year effect to some temporally Wildlife Research Center, unpublished data). Final- invarying mean.

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In our view, some association with time should be conducted using the computational resources of included with year effects in the model. The 1966 (or even in 1986, when JRS conducted his first parameterization presented here was originally BBS analyses). In our view, these methods have for implemented to accommodate fitting in sparse the first time allowed us to conduct analyses of BBS datasets since the trend component provides a data that accommodate the constraints imposed by structure even when no data may exist for a the need to accommodate differences among the particular year (Sauer and Geissler 1990). Autore- thousands of observers who have counted birds for gressive models (e.g., modeling first differences in four decades over most of a continent. Another year effects; Link and Barker 2010:291) provide an critical aspect of these analyses is their flexibility, alternative approach to incorporating time in the with new innovations such as detectability estimation year effects model. Our experience with implement- or additional covariates being able to be directly ing an autoregressive model indicates that trend incorporated as components within the hierarchical estimates generally are similar to those presented model. here, but estimated trends tend to be less extreme The last comprehensive summary of the BBS was (i.e., closer to 0). Analyses of BBS data with published in 1986 (Robbins et al. 1986). Since that alternative models enhances our understanding of time, web applications have made all the data and this complicated dataset, and we hope to expand the analyses readily available to all users through the ‘‘toolkit’’ for analyses of these data with both BBS Summary and Analysis Website (Sauer et al. additional models for analysis and model selection 2011). Results and summaries presented here procedures for better defining which model is best provide a synthesis of those data in a format readily for a data set. readable on a variety of digital displays. This monograph is explicitly designed to be an electronic Conclusion: BBS analysis and document, which we view as the only feasible means technological advances to present results from an annual survey. We intend During a workshop presentation at the 2006 to use the summary analyses and formats presented International Ornithological Congress in Veracruz, in this document to inform (and be updated by) Mexico, Chandler Robbins presented his perspective future versions of the BBS Summary and Analysis on the history and future prospects of the BBS Website. (Robbins 2006). One intriguing aspect of his talk was a description of the effects of advances in technology Acknowledgments on the conduct and management of the BBS. In 1966, communication with observers was via letter, As scientists who use the information from the survey, we acknowledge our debts to Dr. Chandler S. Robbins copies were made with mimeograph machines, and (Frontispiece), who had the vision and energy to develop data were entered into computers via keypunch the survey and remains its greatest advocate, to the machines. Computing resources were very limited, coordinators who have augmented the program and permitting only simple analyses, and logistical maintained the information, and to the thousands of necessity placed limits on routes that could be volunteers who conduct the surveys and dutifully submit surveyed and data that could be entered. Robbins the information to be analyzed and presented to the world. made the point that the capabilities available in 2006 C.S.Robbins,S.Droege,B.Peterjohn,andW. were unimaginable in 1966, and that we must Thogmartin reviewed versions of this document, and C. Handel’s careful review and editing greatly improved the continue to innovate using the technology of the manuscript. J. Aycrigg provided the State of the Birds present. habitats map used in the species group summaries. Although the innovations he mentioned are most Any use of trade, product, or firm names is for obvious in terms of communication and passing descriptive purposes only and does not imply endorsement information to and from observers, present capabil- by the U.S. Government. ities for field methods, analysis, and communication of results are also vastly different. The hierarchical Literature Cited model used to estimate population change can be conveniently fit using the computer-intensive Bart J, Hofschen M, Peterjohn BG. 1995. Reliability of the breeding bird survey: effects of restricting surveys to roads. The MCMC approaches, and these remarkable methods Auk 112:758–761. are allowing for the first time implementation of Birdwatching.com. 1998. The 914 wild bird species of North Bayesian analysis in realistic experimental situations. America. Available: www.birdwatching.com/software/birdlists/ north_amer98.html (May 2013). This important advance is expressed throughout this Butcher GS, Niven DK, Panjabi AO, Pashley DN, Rosenberg KV. monograph, as estimation of population change for 2007. WatchList: The 2007 WatchList for United States Birds. individual species, ranking of change for states, American Birds 61:18–25. provinces, and BCRs, and composite summaries of Butler RW. 2000. Stormy seas for some north american songbirds: are declines related to severe storms during migration? The population change for species groups are all based Auk 117:518–522. on Bayesian inference that could not have been Carson RS. 1962. Silent Spring. Boston: Houghton Mifflin.

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Caughley G. 1994. Directions in conservation biology. Journal of Link WA, Sauer JR. 2007. Seasonal components of avian Animal Ecology 63:215–244. population change: joint analysis of two large-scale monitoring Chesser RT, Banks RC, Barker FK, Cicero C, Dunn JL, Kratter programs. Ecology 88:49–55. AW, Lovette IJ, Rasmussen PC, Remsen Jr. JV, Rising JD, Loveland TR, Sohl TL, Stehman SV, Gallant AL, Sayler KL, Stotz DF, Winker K. 2011. Fifty-second supplement to the Napton DE. 2002. A strategy for estimating the rates of recent American Ornithologists’ Union check-List of North American United States land-cover changes. Photogrammetric Engineer- birds. Auk 128:600–613. ing & Remote Sensing 68:1091–1099. Dail D, Madsen L. 2010. Models for estimating abundance from Lunn DJ, Thomas A, Best N, Spiegelhalter D. 2000. WinBUGS—a repeated counts of an open metapopulation. Biometrics 67:577–587. Bayesian modelling framework: concepts, structure, and Droege S, Sauer JR. 1990. Northern bobwhite, Gray partridge, and extensibility. Statistics and Computing 10:325–337. ring-necked pheasant population trends (1966–1988) from the Martin FW, Pospahala RS, Nichols JD. 1979. Assessment and North American Breeding Bird Survey. Pages 2–20 in Church population management of North American migratory birds. KE, Warner RE, Brady SJ, editors. Perdix V: Gray Partridge Pages 187–239 in Cairns J Jr, Patil GP, Waters WE, editors. and Ring-Necked Pheasant Workshop. Emporia: Kansas Environmental biomonitoring, assessment, prediction, and Department of Wildlife and Parks. management—certain case studies and related quantitative Environmental Systems Research Institute. 1991. Surface modeling issues. Statistical ecology. Vol. 11. Fairland, Maryland: with TIN. Redlands, California: Environmental Systems International Cooperative Pub House. Research Institute, Inc. Nebel S, Mills A, McCracken JD, Taylor PD. 2010. Declines of Flather CH, Sauer JR. 1996. Using landscape ecology to test aerial insectivores in North America follow a geographic hypotheses about large-scale abundance patterns in migratory gradient. Avian Conservation and Ecology—E´ cologie et songbirds. Ecology 77:28–35. conservation des oiseaux 5(2): 1. Available: http://www.ace-eco. Geissler PH, Noon BR. 1981. Estimates of avian population trends org/vol5/iss2/art1/ (May 2013). for the North American Breeding Bird Survey. Pages 42–51 in Nichols JD, Cooch EG, Nichols JM, Sauer JR. 2012. Studying Ralph CJ, Scott JM, editors. Estimating numbers of terrestrial biodiversity: is a new paradigm really needed? BioScience 62: birds. Studies in Avian Biology 6. Lawrence, Kansas: Cooper 497–502. Ornithological Society. Nichols JD, Hines JE, Sauer JR, Fallon F, Fallon J, Heglund PJ. Geissler PH, Sauer JR. 1990. Topics in route regression analysis. 2000. A double-observer approach for estimating detection Pages 54–57 in Sauer JR, Droege S, editors. Survey designs probability and abundance from avian point counts. The Auk and statistical methods for the estimation of avian population 117:393–408. trends. U.S. Fish and Wildlife Service, Biological Report 90(1). Niven DK, Sauer JR, Butcher GW, Link WA. 2004. Population Gregory RD, van Strien AJ, Vorisek P, Gmelig Meyling AW, Noble change in boreal birds from the Christmas Bird Count. DG, Foppen RPB, Gibbons DW. 2005. Developing indicators American Bird 58:10–20. for European birds. Philosophical Transactions of the Royal Pannekoek J, van Strien A. 2005. TRIM 3 Manual (TRends & Society 360:269–288. Indices for Monitoring data). Statistics Netherlands Project Griffith EH, Sauer JR, Royle JA. 2010. Traffic effects on bird No. 100384, 171-01-TMO, 17 February 2005. counts on North American Breeding Bird Survey routes. The Peterjohn BG, Sauer JR. 1999. Population status of North Auk 127:387–393. American grassland birds from the North American Breeding Hannan MD. 2009. Land cover change and the Breeding Bird Bird Survey, 1966–1996. Studies in Avian Biology 9:27–44. Survey: rates of change in relation to roads. Master’s thesis. Rich TD, Beardmore CJ, Berlanga H, Blancher PJ, Bradstreet Brookings: South Dakota State University. MSW, Butcher GS, Demarest DW, Dunn EH, Hunter WC, Hochachka WM, Dhondt AA. 2000. Density-dependent decline of In˜igo-Elias EE, Kennedy JA, Martell AM, Panjabi AO, Pashley host abundance resulting from a new infectious disease. DN, Rosenberg KV, Rustay CM, Wendt JS, Will TC. 2004. Proceedings of the National Academy of Sciences of the Partners in Flight North American Landbird Conservation United States of America 97:303–530. Plan. Ithaca, New York: Cornell Lab of Ornithology, Partners Hutto RL, Hejl SJ, Kelly JF, Pletschet SM. 1995. A comparison of in Flight. bird detection rates derived from on-road versus off-road point Riddle JD, Pollock KH, Simons TR. 2010. An unreconciled counts in Northern Montana. Pages 103–110 in USDA Forest double-observer method for estimating detection probability Service General Technical Report PSW-GTR-149. and abundance. The Auk 127:841–849. Isaaks EH, Srivastava RM. 1989. An introduction to applied Ridgely RS, Allnutt TF, Brooks T, McNicol DK, Mehlman DW, geostatistics. New York: Oxford University Press. Young BE, Zook JR. 2007. Digital distribution maps of the Keller CM, Fuller MR. 1995. Comparison of birds detected from birds of the Western Hemisphere, version 3.0. Arlington, roadside and off road point counts in the Shenandoah National Virginia: NatureServe. Park. Pages 111–116 in USDA Forest Service General Rivera-Milan FF, Ruiz CR, Cruz JA, Mazquez M, Martinez AJ. Technical Report PWS-GTR-149. 2003. Population monitoring of plain pigeons in Puerto Rico. Keller CME, Scallan JT. 1999. Potential roadside biases due to Wilson Bulletin 115:45–51. habitat changes along Breeding Bird Survey routes. Condor Robbins CS. 2006. Establishing the BBS north of Mexico: lessons 101(1): :50–57. learned. Presentation in Workshop on Mexican Expansion of Kendall WL, Peterjohn BG, Sauer JR. 1996. First-time observer the North American Breeding Bird Survey (BBS). Berlanga H, effects in the North American Breeding Bird Survey. Auk 113: Downes C, Pardieck K, Ziolkowski D, organizers. 3 October 823–829. 2006, Veracruz, Mexico. Ke´ry M, Dorazio RM, Soldaat L, van Strien A, Zuiderwijk A, Robbins CS, Bystrak D, Geissler PH. 1986. The Breeding Bird Royle JA. 2009. Trend estimation in populations with Survey: its first fifteen years, 1965–1979. U.S. Fish and Wildlife imperfect detection. Journal of Applied Ecology 46:1163–1172. Service, Resource Publication 157. LaDeau SL, Kilpatrick AM, Marra PP. 2007. West Nile virus Robbins CS, Sauer JR, Greenberg RS, Droege S. 1989. Population emergence and large-scale declines of North American bird declines in North American birds that migrate to the populations. Nature 2059:1–4. neotropics. Proceedings of the National Academy of Sciences Link WA, Barker RJ. 2010. Bayesian inference with ecological of the United States of America 86:7658–7662. applications. New York: Academic Press. Root T. 1988. Atlas of wintering North American birds. University Link WA, Sauer JR. 1994. Estimating equations estimates of trends. of Chicago Press. Bird Populations 2:23–32. Sauer JR, Droege S. 1990. Recent population trends of the eastern Link WA, Sauer JR. 1998. Modeling and estimation of population bluebird. Wilson Bulletin 102:239–252. from the North American Breeding Bird Survey. Ecological Sauer JR, Droege S. 1992. Geographic patterns of population Applications 8:258–268. trends of Neotropical migrants in North America. Pages 26–42 Link WA, Sauer JR. 2002. A hierarchical model of population in Hagan JM III, Johnson DW, editors. Ecology and change with application to Cerulean Warblers. Ecology 83: conservation of neotropical migrant landbirds. Washington, 2832–2840. D.C.: Smithsonian.

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Sauer JR, Fallon JE, Johnson R. 2003. Use of North American Veech JA, Small MF, Baccus JT. 2012. Representativeness of land Breeding Bird Survey data to estimate population change for cover composition along routes of the North American bird conservation regions. Journal of Wildlife Management 67: Breeding Bird Survey. The Auk 129:259–267. 372–389. Sauer JR, Geissler PH. 1990. Annual indices from route regression analyses. Pages 58–62 in Sauer JR, Droege S, editors. Survey Appendix A designs and statistical methods for the estimation of avian population trends. U.S. Fish and Wildlife Service, Biological Report 90(1). Sauer JR, Hines JE, Fallon J. 2008a. The North American Species accounts Breeding Bird Survey, results and analysis 1966–2007. Version Found at DOI: 10.3996/nafa.79.0001.A1. 5.15.2008. Laurel, Maryland: USGS Patuxent Wildlife Re- In this appendix, species accounts are presented search Center. Available: www.mbr-pwrc.usgs.gov/bbs/ bbs2007.html (May 2013). for 426 North American bird species and two Sauer JR, Hines JE, Fallon JE, Pardieck KL, Ziolkowski DJ Jr, combined species. Each species account contains Link WA. 2011. The North American Breeding Bird Survey, (1) general information; (2) a population change Results and Analysis 1966–2010. Version 12.07.2011. Laurel, Maryland: USGS Patuxent Wildlife Research Center. Avail- summary table; (3) a mean relative abundance map; able: http://www.mbr-pwrc.usgs.gov/bbs/bbs.html (May (4) a survey-wide annual index graph; (5) a 2013). population change map; (6) a state and Provincial Sauer JR, Link WA. 2002. Hierarchical modeling of population stability and species group attributes using Markov Chain population change summary graphic; and (7) a BCR Monte Carlo methods. Ecology 83:1743–1751. population change summary graphic. Sauer JR, Link WA. 2011. Analysis of the North American Breeding Bird Survey using hierarchical models. Auk 128:87– 1. General Information presents taxonomic 98. information about the species, along with Sauer JR, Link WA, Kendall WL, Kelley JR, Niven DK. 2008b. A hierarchical model for estimating change in American information on habitats, migration status, and woodcock populations. Journal of Wildlife Management 72: conservation status as described in the 2009 204–214. State of the Birds Report (U.S. NABCI Com- Sauer JR, Pendleton GW, Orsillo S. 1995. Mapping of bird distributions from point count surveys. Pages 151–160 in Ralph mittee 2009). CJ, Sauer JR, Droege S, editors. Monitoring bird populations by point counts. USDA Forest Service, Pacific Southwest N The major habitats in which the species Research Station, General Technical Report PSW GTR 149. occurs are listed, categorized as Marsh, Sauer JR, Pendleton GW, Peterjohn BG. 1996. Evaluating causes of population change in North American insectivorous Grasslands, Aridlands, or Forests (Boreal, songbirds. Conservation Biology 10:465–478. Western, Eastern, or Subtropical). Species Sauer JR, Peterjohn BG, Link WA. 1994. Observer differences in occurring in .3 major habitats are catego- the North American Breeding Bird Survey. Auk 111:50–62. ter Braak CJF, Van Strien AJ, Meijer R, Verstrael TJ. 1994. rized as Generalists. Analysis of monitoring data with many missing values: which N Species that occur primarily in one major method? Pages 663–673 in Hagemeijer EJM, Verstrael TJ, editors. Bird Numbers 1992. Distribution, monitoring and habitat are further categorized as Habitat ecological aspects. Proceedings of the 12th International Obligates. Conference of IBCC and EOAC, Noordwijkerhout, The N Secondary habitats are specialized sub-habi- Netherlands. Voorburg: Statistics Netherlands; Beek-Ubber- gen: Heerlen & SOVON. tats, such as Wetland, Urban/Suburban, and Thogmartin WE, Howe FP, James FC, Johnson DH, Reed E, Coastal areas, which may occur across all Sauer JR, Thompson FR III. 2006. A review of the population major habitats. estimation approach of the North American Landbird Conservation Plan. Auk 123:892–904. N Exotic (nonnative) species are not categorized Thogmartin WE, Sauer JR, Knutson MG. 2004. A hierarchical by habitat. spatial model of avian abundance with application to Cerulean Warblers. Ecological Applications 14:1766–1779. N Species are considered to be of conservation Thomas L. 1996. Monitoring long-term population change: why concern if they are designated as Watchlist are there so many analysis methods? Ecology 77:49–58. species by the National Audubon Society and Thomas L, Burnham KP, Buckland ST. 2004. Temporal inferences from distance sampling surveys. Pages 71–107 in Buckland ST, American Bird Conservancy (Butcher et al Anderson DR, Burnham KP, Laake JL, Borchers DL, Thomas (2007), listed as Birds of Conservation Con- L, editors. Advanced distance sampling. Oxford, United cern (BCC) by the U.S. Fish and Wildlife Kingdom: Oxford University Press. Service (2008), or listed as threatened or U.S. Department of the Interior. 2011. Endangered and threatened wildlife and plants; withdrawal of the proposed rule to list the endangered under the U.S. Endangered Mountain Plover as threatened. Federal Register 76(92): 27756– Species Act. 27799. U.S. Fish and Wildlife Service. 2008. Birds of conservation concern N Migration status is categorized as Permanent 2008. Arlington, Virginia: United States Department of Resident, Temperate Migrant, or Neotropical Interior, Fish and Wildlife Service, Division of Migratory Bird Migrant. Lists of migration status were Management. U.S. Geological Survey. 2007. Strategic plan for the North developed by the State of the Birds Science American Breeding Bird Survey: 2006–2010. U.S. Geological Team (unpublished data). Survey Circular 1307. N We also present percentage of the species’ U.S. North American Bird Conservation Initiative Committee. 2009. State of the Birds, United States of America, 2009. Western-hemispheric range occurring in the Washington, D.C.: U.S. Department of Interior. BBS survey area.

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2. The Population Change Summary table presents trend data (yearly % change) for the long-term (1966–2011) and most recent 10 years (2001–2011), along with 95% credible intervals (CI). The interval-based estimates directly esti- mate change in annual indices based on the ratio of the first and last index for the interval. An alternative estimate of trend, based on a linear regression through the survey-wide annual indices for the long-term period, is also present- ed. Results from the 2 approaches are largely consistent; we present regression results for users who prefer the alternative approach. If the CI for the interval-based estimate does not contain 0.0, we judge the trend estimate to be signifi- Figure A. Map of Bird Conservation Regions refer- cant. We use colors to indicate cautions enced in Appendices A and B. BCR names corresponding associated with results. Green text represents a to codes presented in the map are: S01 Aleutian/Bering need for caution in interpretation of results (e.g., Sea Islands, S02 Western Alaska, S03 Arctic Plains and due to low abundances or small samples); Red Mountains, S04 Northwestern Interior Forest, S05 North- text suggests that a serious deficiency exists in ern Pacific Rainforest, S06 Boreal Taiga Plains, S07 Taiga Shield and Hudson Plains, S08 Boreal Softwood Shield, the results. The level of concern is defined as a S09 Great Basin, S10 Northern Rockies, S11 Prairie consequence of small sample sizes or imprecise Potholes, S12 Boreal Hardwood Transition, S13 Lower estimates: Great Lakes/St. Lawrence Plain, S14 Atlantic Northern Forest, S15 Sierra Nevada, S16 Southern Rockies/ N Sample sizes are defined in terms of number Colorado Plateau, S17 Badlands and Prairies, S18 Short- of random BBS routes on which the species grass Prairie, S19 Central Mixed-grass Prairie, S20 Edwards Plateau, S21 Oaks and Prairies, S22 Eastern was encountered survey-wide. A small number Tallgrass Prairie, S23 Prairie Hardwood Transition, S24 of nonrandom routes exist in the survey Central Hardwoods, S25 West Gulf Coastal Plain/Ouachi- database but were not used in the analysis. tas, S26 Mississippi Alluvial Valley, S27 Southeastern Small sample sizes (,50) are flagged for Coastal Plain, S28 Appalachian Mountains, S29 Pied- caution. Very small samples (,14) are flagged mont, S30 New England/Mid-Atlantic Coast, S31 Penin- as possibly unreliable. sular Florida, S32 Coastal California, S33 Sonoran and Mojave Deserts, S34 Sierra Madre Occidental, S35 N We classified estimated trends as imprecise if Chihuahuan Desert, S36 Tamaulipan Brushlands, and their CIs are sufficiently wide that a change of S37 Gulf Coastal Prairie. 3%/yr change would include 0. We defined extremely imprecise trends as those whose CIs are sufficiently wide that a change of 5%/yr calculated for the grid of locations using a route- change would include 0. regression analysis of the 15 nearest routes. 6. Graph of Population Change by State or 3. Mean Relative Abundance Maps are based Province provides trend estimates from 1966– on BBS data for the interval 2007–2011. Data 2011 for each state and province in which the were averaged by route then abundances were species occurs. Note that the ranking is based on a computed for specific locations defined by a grid hierarchical model that accommodates differences covering the survey area using an area-weighted in precision (Sauer and Link 2002), but the averaging of route data. Note that the stippled estimated trends are shown on the graphic. In area in the northern part of the continent the ranking, imprecise trends tend to be ‘‘shrunk’’ represents areas with very limited samples that toward the mean trend, and consequently the were excluded from our analysis. BBS data from ordering of trends is shuffled to show the actual Alaska and Mexico were also excluded. ordering (based on the predictions from the model) 4. Graph of Survey-wide Annual Indexes shows rather than the naı¨ve ordering. The hierarchical annual indexes of abundance estimated using the model was also used to directly estimate the hierarchical model. Medians of the posterior percentage of state and provinces with decreasing distribution of the yearly indexes are shown as populations. This summary thus displays the solid lines with year markers; lower (2.5%) and estimated state and provincial trends which are upper (97.5%) CIs are shown as solid lines. our best estimate of the data for the region, but also 5. Population Change Maps for the BBS survey portrays our best information regarding attributes area were produced using data from 1966–2011. of the collection of species. The ranks and the Estimates of local annual population change were number of decreasing species are best analyzed

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using the hierarchical model in which inference is 2. The Locale Map for Group shows the based on the underlying parameters. portions of the United States and southern 7. Graph of Population Change by Bird Con- Canada that contain habitats suitable for servation Region (BCR) provides trend esti- species in the group. Data for the contiguous mates for BCRs (e.g., Sauer et al. 2003) in which U.S. were summarized from a map of primary the species occurs (Figure A). These results are habitats prepared by the National Gap Analysis also presented as a precision-adjusted ranking program in conjunction with the 2010 State of using the hierarchical model presented by Sauer the Bird Report (http://www.stateofthebirds. and Link (2002). org); participants in the analysis categorized habitats as characteristic of the species groups. Appendix B For portions of the survey that occur in Canada, we stipple the BCR areas most likely to contain the group. For groups such as generalist species Species group summaries or migration types in which localities cannot Found at DOI: 10.3996/nafa.79.0001.A2. be specified, the entire BBS survey area is Composite summaries of population change for indicated. 19 species groups of North American birds are 3. The Population Change Summary table presented using data from the BBS. Summaries are presents the number of species in the BBS provided for indicator groups described in the State analysis, and the total percentage composite of the Birds Report (U.S. NABCI Committee 2009, change over 42 years with associated 95% http://www.stateofthebirds.org/) and for species credible interval (CI). grouped by migratory status. 4. The graph of Composite Change for Spe- cies Group displays the composite total change 1. General Information includes from the base year (1968) for the collection of species, along with its 95% CI. N Primary Bird Conservation Regions that 5. The Long-term Population Trends graph encompass the geographic regions associated shows the estimated trend from 1966–2011 from with each group; the species in the group, along with their 95% CIs. N Total number of species in the group (see http:// Trends are ranked from largest estimated decline to www.stateofthebirds.org for lists of species); largest increase. This species-by-species summary N Percentage of the species in the group for of change shows the range of change among species which the BBS provides regional summaries. in the group, and the precision of the changes. The BBS does not cover all species of any Species with imprecise trend estimates (large CIs) group, and this percentage shows how contribute little to the overall summaries. comprehensive the BBS coverage is for the 6. The table of Long-term Annual Population group; Change lists species in the group, with their N Average percentage of species’ ranges in the estimated trends (1966–2011), associated 95% BBS survey area. CIs, and sample sizes (N of routes).

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