Ruby-throated Hummingbird on nest

BBA II Overview

This Iowa Breeding Bird Atlas II (BBA II) is intended to provide a comprehensive look at the distribution and breeding evidence for Iowa’s breeding birds and document changes since the first atlas effort. These data were gathered during a five-year period and so represent a snapshot in time. This publication summarizes atlas findings through individual species accounts that also include basic information on each species’ status in Iowa along with their habitat, breeding dates, basic nesting information, and population changes as measured by the federal Breeding Bird Survey (Ziolkowski et al. 2010, U.S. Geological Survey 2020). Comparisons are also made to recent atlas efforts in surrounding states in an attempt to provide a regional context to Iowa’s findings.


Species Accounts

Volunteers entered their data on species and breeding evidence into the BBA website throughout the project. This data is used to evaluate species status changes from BBA I to BBA II. Compare statewide distribution maps between the two surveys and read the summary accounts for each species.

Species Accounts Life Histories of Iowa Breeding Species Added Since BBA I
Gray Catbird nest

Effort & Methodology

436 volunteers contributed 10,645 hours of work to survey 791 sample blocks using protocols developed by the BBA II Steering Committee. 395 grid blocks were systematically placed across the state and 396 habitat sites, split evenly between northern and southern Iowa, were drawn by rotating through the habitat types from smallest to largest percent in order to be sure all habitats were represented.


Some BBA II Results

Alder Flycatcher

Iowa's Breeding Birds

BBA II added a new breeding species to Iowa — Alder Flycatcher. Eighteen new species were confirmed or probable nesters over the results of BBA I and two species – Burrowing Owl and Prairie Warbler – were not encountered during this survey.

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Henslow's Sparrow

Success Stories

Henslow's Sparrow, a threatened species in the state, is no doubt the greatest success story in Iowa's breeding birds because of increases in CRP acres. Habitat changes are no doubt the greatest indicators of species success or failures.

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