Criteria for IBA Designation

IBA Criteria Categories

Click headers to read details.

Category 1 - Sites important to endangered or threatened species in Iowa.

This category includes the current list of Threatened or Endangered bird species for Iowa. Three of these species (Bald Eagle, Piping Plover, Least Tern) are also currently on the federal Threatened and Endangered species list. Species must be breeding 2 years of the previous 6 years (since 1999), with evidence of either confirmed or probable breeding according to definitions given in the Iowa Breeding Bird Atlas, figure 4, page 5.

Endangered Species

  • King Rail
  • Piping Plover
  • Least Tern
  • Northern Harrier
  • Red-shouldered Hawk
  • Barn Owl
  • Short-eared Owl
  • Peregrine Falcon

Threatened Species

  • Long-eared Owl
Category 2 - Sites important to species of high conservation priority in Iowa.

Species selected by the Technical Committee as being of high conservation priority. A site has to support at least three species from this category in order to be nominated. The same three species must be present at the site for 2 or more years out of the previous 6 years (since 1999) with evidence of either confirmed or probable breeding according to definitions given in the Iowa Breeding Bird Atlas, figure 4, page 5.  (See Appendix for habitat assemblages for category 2 species.)

Greater Prairie-Chicken Black-billed Cuckoo Chuck-will's-widow
Common Gallinule American Woodcock Black Tern
Forster's Tern American Bittern Least Bittern
Black-crowned Night-Heron Bald Eagle Broad-winged Hawk
Pileated Woodpecker White-eyed Vireo Bell's Vireo
Loggerhead Shrike Bewick's Wren Veery
Wood Thrush Grasshopper Sparrow Henslow's Sparrow
Yellow-breasted Chat Bobolink Worm-eating Warbler
Kentucky Warbler Hooded Warbler Cerulean Warbler
Category 3 - Sites that contain rare or unique habitat within the state or an exceptional representative of a natural habitat, and that hold important species or species assemblages largely restricted to a distinctive habitat type.

Presumably such sites will include some species from the lists in categories 1 and 2, although the site might just be an especially good woodland, grassland, or other area. (One example would be winter roost sites for large numbers of owls.)

Category 4 - A site that regularly holds significant concentrations of one or more species.

A one-time count of qualifying concentrations must occur 2 out of previous 6 years (since 1999).

The following criteria were selected:

  • 4a. Waterfowl-a threshold of at least 500 waterfowl in winter or 1,000 in migration. Canada Geese were specifically excluded in these counts.
  • 4b. Gulls and Terns-a threshold of at least 1,000 gulls or 100 terns with the following qualifiers: 5,000 for Franklin's Gull, 250 for Black Tern.
  • 4c. Shorebirds-a threshold of at least 500 shorebirds.
  • 4d. Wading birds-a threshold of at least 25 breeding pairs or 100 feeding or migratory birds.
  • 4e. Raptors-a threshold of at least 1,000 total migratory raptors (seasonal total). We also added a category of 100 for wintering birds such as Bald Eagle.
  • 4f. Landbirds-No threshold limits were established.
  • 4g. Single-species concentrations - a minimum of 5% of statewide population for a species.
    • Common Loon - - Minimum 50
    • Pied-billed Grebe - - Minimum 50
    • American White Pelican - - Minimum 750
    • Double-crested Cormorant - - Minimum 500
    • Bald Eagle (migrants) - - Minimum 75
    • American Coot - - Minimum 2,500
Category 5 - Sites important for long-term research and/or monitoring that contribute substantially to ornithology, bird conservation, and/or education.

We noted that some of the raptor viewing sites (e.g., Hitchcock Area, Grammar Grove) may fit in better in this category than in 4e above.

Appendix - Habitat breakdown for Category 2 species.

The birds listed in Category 2 break down approximately as follows relative to habitat categories:

Wetlands-6 species

  • American Bittern
  • Least Bittern
  • Black-crowned Night-Heron
  • Common Moorhen
  • Forster's Tern
  • Black Tern

Riparian habitats-2 species

  • American Woodcock
  • Prothonotary Warbler

Woodlands-11 species

  • Broad-winged Hawk
  • Black-billed Cuckoo
  • Chuck-will's-widow
  • Pileated Woodpecker
  • Bewick's Wren
  • Veery
  • Wood Thrush
  • Cerulean Warbler
  • Worm-eating Warbler
  • Kentucky Warbler
  • Hooded Warbler

Grasslands-3 species

  • Greater Prairie-Chicken
  • Grasshopper Sparrow
  • Bobolink

Savanna/Shrub habitats-4 species

  • Loggerhead Shrike
  • White-eyed Vireo
  • Bell's Vireo
  • Yellow-breasted Chat

IBA Criteria Species

Click an image for enlarging or a scroll them all.

Thanks to Jim Dinsmore for the text and to the following photographers for the use of their images: Larry Dau, Jim Durbin, Bruce Ehresman, Jay Gilliam, Bruce Morrison, Kent Nickell, Jim Rathert, Ross Silcock, Dick Stilwell, and Larry Stone.

IBA Summary

131 total IBAs
SpeciesIBAs RecordedTotal Observations
Greater Prairie-Chicken3136
Black-billed Cuckoo63358
Chuck-will's-widow469
King Rail944
Common Gallinule23205
Piping Plover19240
American Woodcock57270
Least Tern18171
Black Tern54665
Forster's Tern51797
American Bittern42350
Least Bittern33275
Black-crowned Night-Heron37270
Northern Harrier621087
Bald Eagle753145
Red-shouldered Hawk57561
Broad-winged Hawk56564
Barn Owl1249
Long-eared Owl27136
Short-eared Owl32243
Pileated Woodpecker571326
Peregrine Falcon47425
White-eyed Vireo32370
Bell's Vireo54843
Loggerhead Shrike37188
Bewick's Wren328
Veery31300
Wood Thrush631183
Grasshopper Sparrow71757
Henslow's Sparrow58747
Yellow-breasted Chat37415
Bobolink72890
Worm-eating Warbler19153
Kentucky Warbler40577
Hooded Warbler25126
Cerulean Warbler36591