Breeding Bird Atlases (BBA)

Eastern Meadowlark © John Galluzo
Eastern Meadowlark © John Galluzo

What is a Breeding Bird Atlas?

A Breeding Bird Atlas (BBA) is a collection of data about all of the birds that breed in a particular state or region. They're an incredibly valuable tool for conservation that's used to compare species population trends in the same area over many decades.

The data is usually collected by ornithologists and other field researchers, along with many serious amateur birders—community science at its best. The state is divided into 1,055 equal map blocks, and each block is observed for at least 20 hours during breeding season.

More than 650 volunteer citizen scientists worked more than 43,000 hours from 2007-2011 to complete the new Massachusetts Breeding Bird Atlas 2. This work gives us a rare glimpse in the detailed changes in our breeding birdlife, and tells the story of each species history in the state. Join us and explore the Black-capped Chickadee, the Bald Eagle, the Ruby-throated Hummingbird, the Great-horned Owl and more than 200 other species. Learn More

The Massachusetts Breeding Bird Atlas 1 project was a monumental effort to map the distribution of the breeding birds in the Commonwealth, and was the first of its kind in the United States. Results from this work were published in hardcopy in 2003, and presented detailed distribution maps from the 1974-1979 Breeding Bird Atlas 1 surveys. Read species accounts, view maps and data from Massachusetts' first Breeding Bird Atlas. Learn More