Breeding Bird Atlas

What is a Breeding Bird Atlas?

A Breeding Bird Atlas is a comprehensive survey that inventories bird species that breed in a state or province. Bird surveyors look for breeding birds in pre-selected areas called “sampling blocks” that are distributed throughout the state or province. To fully document and map the distribution of breeding birds, the survey lasts for many years.

In Indiana, the first Breeding Bird Atlas was conducted from 1985 to 1990, and its results were published (Castrale, Hopkins, and Keller 1998). This atlas provides baseline information on the statewide distributions and relative occurrences of 162 breeding bird species.

Twenty years later, survey methods were repeated to analyze changes in bird distributions and abundances and to inform changes in land use, climatic patterns, and other environmental variables. Surveys were conducted between 2005 and 2011, and their results were published in 2023 (Castrale 2023). The Indiana atlas of 2005-2011 provides tables detailing regional atlas frequencies for 201 bird species with 198 maps displaying species distributions.

Why are the Breeding Bird Atlases important?

Birds are excellent indicators of environmental health, so changes in bird populations may benefit people by providing early warning signs of changes that may affect human health.

When do birds breed in Indiana?

Birds typically breed in Indiana throughout spring and summer, but there are many exceptions. For example, bald eagles will begin courtship displays and nest building in December. The safe dates chart provides time periods for each species when most migrants have left and the birds that remain are likely nesting.

Want to learn more about Indiana’s Breeding Bird Atlases?

If you would like to request electronic copies of an Indiana Breeding Bird Atlas or more information, please contact the Indiana DNR’s state ornithologist, Allisyn-Marie Gillet, at agillet@dnr.IN.gov. The Indiana Breeding Bird Atlas, 2005-2011 is available with high quality maps upon request.

Want to help Indiana’s birds?

Bird monitoring in Indiana is funded, in part, by citizen donations to the Indiana Nongame Wildlife Fund. To support this project and others like it, visit our donate page.