BLACK TERNS BENEFIT FROM CATTAIL MANAGEMENT IN THE NORTHERN GREAT-PLAINS

In the northern Great Plains, cattails (Typha spp.) have overgrown man y wetlands, contributing to a decline in numbers of Black Terns (Chlid onias niger). Since 1991, wildlife agencies have applied glyphosate-ba sed herbicide to cattail-dominated wetlands with the objectives of inc reasing duck (Anatinae) abundance and reducing crop-depredating blackb ird (Icterinae) populations. In 1990 and 1991, we serially applied gly phosate-based herbicide to cattail-dominated wetlands in North Dakota to assess the influence of habitat changes on birds. Numbers of Black Terns and selected ducks species were positively correlated with open water and dead cattails (r(17) range: 0.77-0.46); whereas, blackbird n umbers were positively related with live cattails (r(17) range: 0.52-0 .48). Black Tern numbers were positively related (r(17) range: 0.76-0. 49) to numbers of Mallards (Anas platyrhynchos), Blue-winged Teal (A. discolor), Redheads (Anthya americana), and Yellow-headed Blackbirds ( Xanthocephalus xanthocephalus), suggesting some common habitat require ments among these species. Cattail management programs designed specif ically to enhance duck use and decrease Red-winged Blackbird (Agelaius phoeniceus) numbers probably benefit Black Terns.