Birds of Some Iowa Wetlands in Relation to Concepts of Faunal Preservation

Forty-one species of birds nested in the prairie-wetlands complex of Dewey's Pasture during the period 1962 to 1974. Numbers of pairs and nests were recorded annually for the ducks and other waterbirds that dominated the avifauna, but observations on terrestrial species were less detailed and only frequency of occurrence data are presented. These data on bird use of a relict pothole area demonstrate the dynamics of bird populations in relation to habitat conditions. Abundance and diversity of waterbirds were positively correlated with increasing water depth. Problems of conserving typical avifaunas in small wetlands units surrounded by intensive agriculture are discussed in reference to extirpated species and to the role of habitat size and diversity in maintaining species richness.