Population Estimates Database: About the Database

The PIF Population Estimates Database provides breeding population estimates for all landbird species in the continental USA and Canada at various spatial scales (e.g., global, regional, state/provincial). The vast majority of these estimates are derived from the North American Breeding Bird Survey (BBS) using the approach developed by Rosenberg and Blancher (2005) and updated by Blancher et al. 2013. The Population Estimates Database and corresponding Handbook are products of the PIF International Science Committee and are intended to serve as a companion to the Partners in Flight Landbird Conservation Plan (Rosenberg 2016), although most estimates have since been updated.

What’s new in Version 3

Version 3.0 incorporates BBS data from the decade 2006-2015 (previously 1998-2007) and addresses some of the recommendations suggested by Thogmartin et al. (2006) but does not yet fully address other limitations. By far, the most substantial change to the database comprises the incorporation of quantitative uncertainty bounds around population estimates for most species (see Stanton et al. (2019) for details). Version 3.0 also incorporates the latest independent estimates for dozens of uncommon, rare or range-restricted species from a variety of sources. Unlike version 2.0, estimates for the BCR x state/province polygons are no longer viewable online, but are still available for download.
The Handbook for Version 3.0 of the database describes all changes that have been made to the database since 2007 (Version 1.0)—including the additions documented in the Handbook for Version 2.0—and therefore serves as a single source document describing the current database.

Why estimate landbird populations?

Estimates of population size are an important component of bird-conservation planning for several reasons. First, an order of magnitude category of global population size is one of six factors used to assess overall conservation vulnerability as part of the PIF species assessment process (see Panjabi et al. 2019), with species having smaller global populations being more vulnerable than species with larger populations. Second, even crude estimates of population size serve to underscore the magnitude of our task to restore and conserve populations of declining common birds, often involving millions of individual birds that will require millions of acres of restored or improved habitats. As such, these estimates may serve as the first step in setting quantitative conservation objectives within states or Bird Conservation Regions, and an important component of Conservation Design. Finally, order-of-magnitude population estimates provide a basis for comparing independent estimates of concentrations of birds during migration and especially avian mortality from anthropogenic sources such as communication towers, buildings, or cats.

Give us your feedback!

Partners in Flight continues to seek input and relevant data from throughout the bird- conservation community to improve these estimates. To provide feedback on PIF population estimates, please contact the PIF Database Manager.