Broad-scale landbird monitoring in North America is largely count-based (e.g., the North American Breeding Bird Survey [BBS]) and directed at monitoring relative abundance and trends (Bart 2005, Sauer et al. 2008). Such data are invaluable for identifying conservation targets and priorities (Rich et al. 2004), but are less useful for directing research, management, and conservation actions because they cannot provide direct information on causes of trends (DeSante et al. 2005a). Even when abundance and trend are estimated accurately and precisely, links between these parameters and environmental factors potentially driving the trends may be obscured by limiting factors acting at times and places other than when and where abundance and trend are measured (e.g., for migratory species, abundance and trend measured on the breeding grounds but population limitation occurring on the wintering grounds: Marra et al. 1998, Nott et al. 2002). Avian conservation partnerships, such as Partners In Flight (PIF) and the North American Bird Conservation Initiative (NABCI) have recently recognized the importance of implementing full-annual-cycle monitoring and management of bird populations.
Assessing and monitoring demographic vital rates (i.e., reproduction, recruitment, survival) in addition to abundance and trend can enhance the effectiveness of avian habitat management and landbird conservation (Saracco et al. 2008). Indeed, determining the vital rates that are the proximate demographic drivers of population change is critical for informing effective avian conservation because management can then (a) be directed at the annual-cycle stage that actually limits the population; (b) be based on true indicators of habitat quality, incorporate the effects of sources and sinks, and avoid ecological traps; and (c) be based on predictive models whereby critical vital rates are modeled as functions of environmental variables such as land use, habitat, and climate (DeSante et al. 2001, Saracco and DeSante 2008). Understanding the contribution of the various vital rates to the dynamics of bird populations not only has important conservation implications, it is also fundamental to our basic understanding of avian population dynamics (Sillett et al. 2000, Sillett and Holmes 2002, Julliard 2004).
Application of standardized constant-effort mist netting and modern capture-mark-recapture analytical techniques can provide an effective means of monitoring demographic rates of many landbird species (Pollock et al. 1990, Lebreton et al. 1992, DeSante et al. 2004, Peach et al. 2004, Robinson et al. 2007). Such an effort was initiated in North America by The Institute for Bird Populations (IBP) in 1989 with the establishment of the Monitoring Avian Productivity and Survivorship (MAPS) program (DeSante 1992). The MAPS program consists of a network of constant-effort mist-netting and bird-banding stations operated using a field protocol (DeSante et al. 2014) that was standardized in 1992 when a 4-year pilot project (1992-1995) was funded by the U.S. Fish and Wildlife Service that evaluated and confirmed the usefulness of the program. To date, more than 1,200 stations have been established as part of the MAPS program, and nearly 25% of all stations ever registered with the MAPS program have been operated for more than 10 years. Over 80% of MAPS stations have been operated by independent bird banders (i.e., trained citizen scientists) or non-governmental organizations (although governmental agencies provide funding for the operation of some of these stations). The remaining stations have been operated by biologists and interns recruited and trained by IBP, often with financial assistance from governmental agencies mentioned in the Acknowledgements.
The overall goals of the MAPS program are fourfold (DeSante and Kaschube 2009). The first is to collect long-term data on the vital rates (primary demographic parameters, such as population growth rate [\(\lambda\)], adult apparent survival probability, productivity) of North American landbirds at multiple spatial scales ranging from station-specific and local-landscape to regional (e.g., North American Bird Conservation Initiative Regions [BCRs]) and continental (program-wide). The second is to describe temporal and spatial patterns in these vital rates, as well as relationships among them, particularly relationships between \(\lambda\) and other critical vital rates, in order to make inferences regarding the primary demographic drivers of temporal and spatial variation in \(\lambda\), especially as these results can inform conservation and management of species with declining population trends. The third goal is to model the vital rates that appear to be the proximate demographic drivers of temporal and spatial patterns of population change as functions of (1) ecological characteristics and population trends of the various species, (2) station-specific and landscape-level habitat characteristics, and (3) spatially explicit weather and climate variables, to help formulate specific management and conservation strategies to reverse population declines and maintain stable or increasing populations. The fourth major goal of the MAPS program is to evaluate and improve, through an adaptive management process, the effectiveness of the management and conservation actions implemented by monitoring the vital rates targeted by those actions.
In 2010, The Institute for Bird Populations proposed a suite of analyses to be conducted on 15 years (1992-2006) of MAPS data that would culminate in the production of a dedicated website, Vital Rates of North American Landbirds, through which the results of those analyses would be disseminated. This proposed effort had two major objectives. The first was to provide estimates of vital rates for as many species of North American landbirds as possible, and to document and describe temporal (annual) and spatial (at the scale of BCRs) variation in these demographic parameters. Vital rates to be estimated included population change (\(\lambda\)), adult apparent survival, recruitment into the breeding population (including local and external sources of recruitment), residency (proportion of resident, as opposed to transient, individuals among newly captured adults), index of adult population density, breeding performance (i.e., productivity, estimated as the reproductive index, the ratio of young to adult individuals), and post-breeding effects on recruitment (i.e., the ratio of recruitment/reproductive index, which includes effects of first-year survival of young and immigration of adults). The second objective was to examine temporal and spatial correlations among lambda and the other vital rates of these species to (a) determine the proximate demographic correlates of the observed temporal variation in population changes and spatial variation in population trends, (b) make inferences about potential demographic drivers of the observed temporal and spatial variation in lambda, and suggest whether these drivers might act primarily on the breeding or non-breeding ranges and during the breeding or non-breeding seasons, and (c) disseminate these results to inform conservation and management efforts for these species.
In achieving these two objectives, this website presents results of temporal and spatial analyses for 158 species for which at least 75 adult individuals were captured, marked (banded), and released during the 15-year period 1992-2006 and at least 14 between-year recaptures were recorded during the 14 years 1993-2006. For each of these 158 species, we present visual displays of results: sampling information and graphs of the year-constant and annual estimates (along with 95% confidence limits, when available) for each of the eight demographic parameters estimated from temporal analyses; and sampling information and maps of BCRs showing color-coded BCR-specific estimates for these same eight parameters from spatial analyses. In addition, for each of the 158 species, we present summary tables of means, standard deviations, and coefficients of variation (CVs) from both temporal and spatial analyses, as described above; and scatterplots and correlation matrices for pairwise correlations among the estimated demographic parameters. We also present species account narratives for each of these 158 species, in which we attempt to summarize and interpret these results, particularly as they relate to the demographic correlates of both temporal population changes and spatial differences in population trends, and can potentially inform conservation and management of these species. The completion and dissemination of this website thus accomplishes the first two major goals of the MAPS program and sets the stage for efforts to address the third and fourth goals as well.
Although the results presented on this website represent the best snapshot of broad-scale landbird demographics in North America that we are able to provide at this time, it should be noted that analytical methods for estimating vital rates and addressing questions related to assessing demographic drivers of population change have advanced rapidly in recent years (e.g., Robinson et al. 2014). For example, Bayesian analysis of a hierarchical spatially autoregressive capture-recapture model has been employed to provide spatially explicit (1-2\(^\circ\) blocks) and year-specific estimates of adult apparent survival and residency from MAPS data for Wood Thrush (Saracco et al. 2010) and Common Yellowthroat (Saracco et al. 2012). Cormack-Jolly-Seber models have also been employed on MAPS data to examine the effects of latitude, region, residency status, El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and the resulting seasonal precipitation patterns on adult apparent survival of Swainson‘s Thrush (LaManna et al. 2012). Finally, in the interest of providing improved inferences about demographic rates and the status of populations at multiple spatial and temporal scales, we are developing new approaches that formally combine data from the BBS, MAPS, and other sources (e.g., the Monitoreo de Sobrevivencia Invernal [MoSI] program; DeSante et al. 2005b) under a unified modeling framework. We aim to make results of these analyses available for many of the best-represented species on this website in the near future. Until that time, we suggest that the spatial and temporal patterns in vital rates presented herein provide important new insights into the dynamics of North American landbirds, and we hope that these insights will stimulate more focused investigation and hypothesis testing which can lead to effective conservation action.