Nest initiation and end dates for eight grassland bird species in Wisconsin and Illinois

We used nest records from published grassland bird studies done in Wisconsin and Illinois to compile a dataset for 8 obligate grassland bird species Study sites were clustered in southwestern Wisconsin near Mt. Horeb (43.0167°N, 89.7500°W); sites were located in Dane, Grant, Green, Iowa, Lafayette, Monroe, and Rock counties. In northern Illinois, study sites were located in Lee, Ogle, Will, Grundy, Carroll, and Jo Daviess counties (40.9822 to 42.2356°N, -87.5433 to -90.3489°W).The dataset consists of 3257 nests with observations on nest initiation date (date first egg laid), nest fate (success, failure), number of fledglings, and nest end date (date the nest either failed or fledged at least one nestling). The species were Bobolink, Dickcissel, Eastern Meadowlark, Grasshopper Sparrow, Henslow's Sparrow, Savannah Sparrow, Vesper Sparrow, and Western Meadowlark.Â