Breeding Bird Atlas 2 Methods

What is a Breeding Bird Atlas?

Great Blue Heron
Great Blue Heron - John Sill

A Breeding Bird Atlas is a research project designed to map the breeding ranges of all species in a specific region. Volunteers are assigned to an area, usually called a block, and the area is surveyed for evidence of breeding bird activity. Once a species is found breeding in a block no further evidence is collected. This makes an atlas a measure of the distribution of a species, not the abundance of a species.

Atlases are designed to be repeated to evaluate the change in the range of each species. In Massachusetts we have completed two Atlas projects.


While each Breeding Bird Atlas has slight modifications to its methods, all of them follow the basic field protocols set out in The Atlas of Breeding Birds of Britain and Ireland by Sharrock (1976). The volunteers in the Massachusetts Breeding Bird Atlas 2 received detailed field methods.

Read a summary of the field methods.

BBA2 Handbook 409.76 kB