This distinctive, medium-sized waterbird commonly nests on the Refuge. It only breeds in the northern United States and into Canada. It has an elaborate courtship display and an array of loud mating vocalizations. Once paired, it builds a nest from wetland plant material over water, within or near emergent wetland cover. This species will sometime nest in isolation and other times as part of a colony of other over water marsh nesting birds. In mid- to late summer it can be seen swimming in Refuge wetlands with its babies atop its back. This expert swimmer prefers to respond to danger by diving, rather than flying.

This small, but striking duck has always used the Refuge’s extensive wetland areas for spring and fall migration habitat, but it is a relative newcomer to the Refuge (and northwestern Minnesota) as a nesting species. The first documented nesting of buffleheads on the Refuge was in 1985. Now they are the second most abundant nesting diving duck on the Refuge. Research in cooperation with the University of North Dakota is presently underway to gain an improved understanding of their habitat use during the nesting season. 

Known for its distinctive, far-carrying booming call, the American bittern is heard more often than seen. Biologists at Agassiz Refuge, along with many partners, have studied the life history, ecology and management of the American bittern. This bird was selected for study because of its declining populations nationwide, (especially in the Upper Midwest), contaminant concerns, and lack of understanding of their basic life history. This research resulted in an improved understanding of what wetland habitat conditions Refuge staff can provide for this species.

Some of the slight topographical rises on the otherwise ‘flat as a pancake’ Agassiz Refuge support one of America’s most imperiled ecosystems – oak savanna. Several hundred acres of this habitat are found on the eastern half of the Refuge, where fire-dependent bur oak and tallgrass prairie come together. This habitat has become degraded in many areas because fire and large grazing animals are no longer part of the landscape and with the introduction of non-native grasses and shrubs. Refuge staff are focusing oak savanna management efforts on reintroducing properly timed prescribed fire as a management tool, as well as direct removal of aspen from degraded savannas. Oak savannas provide habitat for a wealth of bird, mammal, and insect species, including red-headed woodpeckers, black bears, deer, American kestrels, and eastern kingbirds on the Refuge.

 Sedge meadows are areas of saturated soil filled with sedges, rushes, and water-loving grasses, with some forbs. Historically more than three-quarters of Minnesota’s original wetlands were sedge meadows and were indispensable habitat for plants like lilies, irises, and native orchids. They are increasingly rare due largely to direct habitat conversion (e.g., development, agricultural production), and disruption of an area’s natural hydrology (e.g., drainage). Sedge meadows can be supported by surface water or groundwater runoff. Agassiz Refuge has vast acreages of sedge meadow habitat, but much of it has become invaded over the years by cattail, exotic grasses like reed canary grass, or willows. Reestablishing sedge meadow habitat is a Refuge priority and ongoing challenge. These areas provide important foraging and nesting habitat for a variety of wetland-dependant bird species, including those of Regional Conservation Priority, like the Le Conte’s sparrow, sedge wren, sharp-tailed sparrow, and yellow rail.

The Refuge maintains 2,380 acres in coniferous bog for the benefit of such species as the olive-sided flycatcher, Connecticut warbler, orchids, and ferns. Coniferous bogs are found mostly within the designated Wilderness Area of the Refuge and consist primarily of a black spruce and tamarack overstory. The understory in the Refuge bogs contain especially interesting species, including carnivorous pitcher plants and sundews.