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The North American Breeding Bird Survey was initiated in 1966 to monitor bird populations over large geographic areas.

A juvenile Yellow-breasted Chat looking out from within a dense green shrub
Breeding Bird Survey data show that the shrub-loving, yellow-breasted chat has experienced a population decline of 3% per year in Maryland since 1966, when the survey began. Photo Credit: Mikey Lutmerding/USGS.

In the mid-twentieth century, the success of new, post-war pesticides ushered in a new era of synthetic chemical pest control. As pesticide use grew, concerns about their effects on wildlife began to surface, as epitomized by Rachel Carson in “Silent Spring.” Local studies had attributed some bird kills to pesticides, but it was unclear how, or if, bird populations were being affected at regional or national levels. In 1966, responding to this concern, researchers at the Patuxent Wildlife Research Center (now the U.S. Geological Survey Eastern Ecological Science Center) initiated the North American Breeding Bird Survey to monitor bird populations over large geographic areas.

What Is the Breeding Bird Survey?

The Breeding Bird Survey (BBS) is a multinational, long-term, continental avian monitoring program designed to track the status and trends of North American bird populations. The U.S. Geological Survey (USGS) leads the effort in collaboration with Environment and Climate Change Canada and the Mexican National Commission for the Knowledge and Use of Biodiversity.

How Does the Breeding Bird Survey Work?

Each year during the height of the avian breeding season, thousands of community scientists who are skilled in avian identification collect bird population data from roadside survey routes.

  • Survey routes are roughly 25 miles long and are comprised of 50 point counts.
  • Each point count is a bird count that lasts 3 minutes. In the allotted 3-minute time, an observer counts all birds heard or seen within a 0.25-mile radius.
  • Surveys start one-half hour before local sunrise and take about 5 hours to complete.
  • Routes are surveyed once per year by a qualified observer assigned to the task.
  • There are over 4,800 survey routes located across the continental United States, Canada and northern Mexico.

How Are Breeding Bird Survey Data Used?

BBS data provide an index of population change and are used to estimate population trends and relative abundances at various geographic scales and time periods. The data play an essential role in assessing bird population changes and they inform national and regional avian conservation and management actions.

  • Raw and summarized count data are provided free online for over 700 bird species.
  • Population trend estimates are provided for over 500 bird species.
  • Federal and state conservation policy and land use planners combine BBS data with other indicators to assess species management priorities.
  • BBS data have identified critical declines of neotropical migrants and grassland species, galvanizing conservation action for these birds.
  • Most recently, BBS data were used to document the loss of nearly 3 billion birds over the last 50 years spurring the “Road to Recovery” conservation initiative.
  • Over 800 peer-reviewed publications have used BBS data as the primary means to answer a research question.
A colorful sunrise over hay fields in western Maryland viewed along the Jennings BBS route
Sunrise along the Jennings route in Garrett County, one of 54 roadside bird counts conducted in Maryland as part of the North American Breeding Bird Survey. Photo Credit: Mikey Lutmerding/USGS.

Why Is the Breeding Bird Survey Important?

As the sole source of long-term, large-scale breeding season population change data for hundreds of bird species in North America, the BBS program fulfills, in part, the Department of Interior mandate under the Migratory Bird Treaty Act to conserve and manage migratory bird species. The BBS helps keep common birds common by providing the data needed to annually assess populations, alerting wildlife management agencies to take action before they reach critically low levels. In addition, the survey provides critical avian count data for model-based conservation planning.

Example Application of Breeding Bird Survey Data: Wood Duck Harvest Regulations

Each summer, at the request of the U.S. Fish and Wildlife Service Migratory Bird Program, the Eastern Ecological Science Center provides a provisional release of BBS wood duck data to inform annual harvest regulations in the Atlantic Flyway. Wood duck is the most harvested waterfowl species in the Atlantic Flyway and among the five most popular hunted ducks in the United States. Heightened public interest in wood duck has garnered increased attention on regulations and habitat management, and the U.S. Fish and Wildlife Service has met this challenge by drawing from the most scientifically reliable population data available to inform its population modeling and structured decision-making work. BBS fits this task better than most waterfowl surveys do because wood ducks are widely distributed, occur at relatively low densities, and prefer heavily forested habitats – and BBS observers are out there in those places performing the count!

 

Learn more about the North American Breeding Bird Survey at: https://www.usgs.gov/centers/eesc/science/north-american-breeding-bird-survey

 

A version of this article appeared in the Friends of Patuxent Fall 2022 Newsletter.