BBA II Overview


Yellow-headed Blackbird - Kip LadageFrom 2008 to 2012 Iowa conducted its second Breeding Bird Atlas project.

The first atlas project was conducted from 1985 through 1990 and new data from 2008 through 2012 shows us range expansions and contractions over the past 20+ years. During this time the landscape changed with the use of CRP increasing our grasslands.

Brown Thrasher nest - Wolf Oesterreich With 791 blocks and a goal of 20 hours per block (15,820 total hours), the undertaking was immense but atlassers began the process in 2008.  The first years were challenging since many of the habitat blocks are along rivers and it seemed like the rivers were always flooding.  As can be seen in the chart below, the effort increased considerably in the drought year of 2012, the first time many of these lowland areas could be explored.  Helping immensely in this effort was a 2012 grant from the Iowa DNR to hire techs assigned to survey under-reported blocks.  These two factors, combined with the great effort of volunteers, provided many great data points in this final year.

Brown Thrasher fledgling - Wolf Oesterreich Volunteer efforts as well were significant.  Beginning in 2010 the steering committee identified clusters of under-reported blocks and the BBA Coordinator organized block-busting events in these areas throughout the state.  These organized activities brought together local birders and those who were looking for some new adventure in a different part of the state and helped to add quality data to these blocks.  The coordinators also did a great job of maintaining engagement with the volunteer community through periodic newsletters which are still great fun to read.

For more information on the criteria used for BBA II and how blocks were selected, please read our methodology page and view the maps.

Map used with permission of the State of Iowa Counties: Buena Vista, Calhoun, Cherokee, Clay, Dickinson, Emmet, Humboldt, Ida, Kossuth, Lyon, O'Brien, Osceola, Palo Alto, Plymouth, Pocahontas, Sac, Sioux, Webster, WoodburyCounties: Adair, Audubon, Carroll, Cass, Crawford, Guthrie, Harrison, Monona, Pottawattamie, ShelbyCounties: Adams, Fremont, Mills, Montgomery, Page, Ringgold, Taylor, UnionCounties: Butler, Cerro Gordo, Floyd, Franklin, Grundy, Hamilton, Hancock, Hardin, Mitchell, Winnebago, Worth, WrightCounties: Boone, Dallas, Greene, Jasper, Marshall, Polk, Poweshiek, Story, TamaCounties: Appanoose, Clarke, Davis, Decatur, Keokuk, Lucas, Madison, Mahaska, Marion, Monroe, Wapello, Warren, WayneCounties: Cedar, Iowa, Johnson, Linn, MuscatineCounties: Allamakee, Benton, Black Hawk, Bremer, Buchanan, Chickasaw, Clayton, Delaware, Fayette, Howard, WinneshiekCounties: Clinton, Dubuque, Jackson, Jones, ScottCounties: Des Moines, Henry, Jefferson, Lee, Louisa, Van Buren, Washington
The following table summarizes the results of BBA II by regions of the state. Hover over a region on the map to see which counties are included in a given region.
Region# of BlocksHoursAll SpeciesConfirmed/Probable
North West1521,762174148
North Central871,187169144
South Central1091,459169132
East Central52792158125
West Central76852155121