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State of the Birds Report

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Our Approach

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Locations of North American Breeding Bird Survey routes (left) and Audubon Christmas Bird Counts (right), which provided the bulk of long-term bird monitoring data used in this report. Both of these surveys rely on thousands of volunteer birders.

Assessment of U.S. Birds by Habitat

Because healthy bird populations depend on both the quality and quantity of their habitats, our State of the Birds approach focuses on species that are dependent on a single primary habitat type—we define these species as habitat obligates. For this report, we identified obligate species in oceans, coasts, inland wetlands, forests, aridlands, and grasslands, as well as species found on Hawai`i, Puerto Rico, and the U.S. Virgin Islands, and other U.S. island territories. See a listing of species in each habitat and a map of U.S. habitats based on USGS GAP National Land Cover.

Bird Population Indicators: A Measure of Environmental Health

The underlying principle of State of the Birds reports is that the health of populations of bird species found only within a habitat reflects the overall health of that habitat. To assess the health of bird populations, we used data from several continental-scale monitoring programs that have provided consistent data since 1968 (or since 1974 for shorebirds). For each obligate species, we assigned a habitat type and estimated the population change up to 2012 with the appropriate survey, then combined the estimates of trends for species in the habitat into a composite estimate of change. This composite estimate of change is used as the bird population indicator for the habitat. The statistical approaches we use for estimation of the bird population indicators were first used in the 2009 State of the Birds report (see Surveys and Analysis Methods).

Tracking Change in U.S. Bird Populations

In this report, we use information from the North American Breeding Bird Survey, the Audubon Christmas Bird Count, the U.S. Fish and Wildlife Service’s Spring Breeding Ground Waterfowl Survey, and the American Woodcock Singing-ground Survey. A new indicator was developed from monitoring data of migrating shorebirds, using data from the International Shorebird Survey, the Atlantic Canada Shorebird Survey, and the Ontario Shorebird Survey.

Species of Conservation Concern: The 2014 State of the Birds Watch List

The Watch List, presented by the North American Bird Conservation Initiative U.S. committee, includes those birds of highest conservation concern occurring in the U.S. and its territories. The 2014 Watch List represents the first time the approach described below has been applied consistently to all of our birds. It includes many of the species listed under the Endangered Species Act, additional species that require immediate conservation attention, and others on or near the brink of being threatened that warrant continued vigilance. The Watch List is re-evaluated every 5 to 10 years on the basis of improved methods of evaluation, better data, and changes in the status of populations.

To assess species for inclusion on the Watch List, a NABCI team reviewed the conservation status of more than 800 bird species in the continental U.S., Hawai`i, U.S. oceans, and territories. The team drew on data from long-term monitoring surveys, regional assessments, and expert knowledge of species’ populations and threats to each major habitat. Specifically, we assessed the vulnerability of each species to possible extinction, based on six key factors: size of global breeding population, breeding and non-breeding range size, threats to breeding and non-breeding habitats, and population trends. Species that did not meet Watch List criteria for threats or range size, but experienced significantly declining trends (50% or more loss over 45 years), are defined as Common Birds in Steep Decline. The complete results of this assessment can be found in the Partners in Flight Species Assessment Database maintained by the Rocky Mountain Bird Observatory.

  

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