Brewer, G.L. 1992. 1991 Summary Report: Location of breeding colonies and evaluation of critical nesting habitat for the black tern (Chlidonias niger) in northwestern Minnesota: Kittson and Roseau Counties. Report submitted to the Minnesota Department of Natural Resources. 10 pp.
In recent years, a decline has been noted in the number of black terns (Chlidonias niger) over most of its range. Although the causes of this decline are not well understood, factors that have the potential to impact black terns are habitat loss, environmental contaminants, nest predation, competition for nest sites or food, adverse weather, and human disturbance.
Black terns were once listed as an abundant summer resident in Minnesota, breeding throughout the state. Currently, black terns are thought to breed throughout Minnesota, except for sections of the southeast and northeast. Breeding has not been confirmed recently in a number of counties, however, and the number of black terns is generally thought to be declining in Minnesota. Surveys are needed to document the number of breeding adults, locations of nesting sites and their characteristics, and reproductive success in order to determine the status of black terns in Minnesota and its requirements for protection. Information is particularly lacking for northwestern Minnesota, where intensive agriculture and the draining of wetlands have eliminated suitable habitat in an area where breeding has been documented.
The objectives of this study were to locate suitable habitat for black terns in Kittson and Roseau Counties in northwestern Minnesota, survey these areas, document evidence of breeding, and describe the habitat features and extent of black tern breeding colonies. This preliminary information will confirm the presence and magnitude of black terns breeding in these counties, and indicate potential conservation needs for these populations.