Important Bird Areas

Agassiz National Wildlife Refuge IBA

Minnesota

Direction: 12 miles north of Thief River Falls, MN on MN Hwy. 32 and 11 miles east on Marshall County Road 7 (22996 290th Street).

Location: Aspen Parkland in northwestern Minnesota located approximately 70 miles south of the U.S.-Canada border and 50 miles east of the MN-ND border.

Prominent Features: Situated in the transition zone between the tallgrass prairie and prairie pothole region to the west and the coniferous forest to the east. Very flat with a one-two foot elevation decrease per mile from east to west. A 4,000 acre Wilderness in the north central part of the refuge is a black spruce & tamarack bog growing with many unique bog plants such as leatherleaf, Labrador tea, bog birch, blueberry, Stemless ladyslipper, pitcher plant, sundew and sphagnum moss.

Habitat: Open Water and Freshwater Marshes-37,400 acres; Shrubland (Willow)-11,650 acres; Woodland-9,900 acres; Upland Grassland-1,710 acres; Cropland-170 acres; Developed Land 670 acres. Depth of wetlands varies from 0-4 feet with an average depth of 2 feet. The east side of the refuge has the highest elevations with bur oak woodlands. Grasslands consist mainly of introduced cool season grasses. Naturally occurring native prairie plants are scarce throughout the refuge.

Ornithological Summary

The Refuge hosts an average of 40,000 ducks and 14,000 geese during migration.
Long term average breeding population of ducks is 7,145 pairs. When large pools are in drawdown Agassiz NWR will host thousands of shorebirds.
In 2001 the maximum one day shorebird count was 1600. The largest Franklin?s Gull colony in Minnesota, and one of the largest in North
America, nests in Agassiz Pool. Numbers vary between 10,000 to 81,000 breeding birds over
the past 15 years. - Fall populations of migrating Sandhill Cranes number between 500 and 1,000. Trumpeter Swan nested on the refuge for the first time in recent history in 2003. There are large populations of American and Least Bitterns that have had research
projects in the past 10 years. Black-Crowned Night Herons are colonial nesters that number in
the hundreds. Genetic study of Canvasbacks indicated that the Agassiz population may be
unique and usually numbers between 200 and 350 pairs. Other species of conservation
concern that nest at Agassiz NWR but do not have population estimates are Northern Pintail,
Lessor Scaup, Northern Goshawk, American Woodcock, Black-billed Cuckoo and Whip-poorwill. There is a long
history of management and ecological research on waterfowl species including brood counts,
pair counts, duckling survival and nest predation.

Conservation Issues

Drainage: The threat is from additional drainage upstream bringing too much water too fast to the refuge. Refuge staff are participating in county water plan development , mitigation teams, and Red River Basin Board committees.
Invasive Species: Biological control agents have been released for Canada thistle and leafy spurge. Limited spraying of leafy spurge has also occurred. Combinations of treatments (fire, drawdown, flooding and herbicide) are bring used to control hybrid cattail.
Pesticides: Testing of birds and mammals has been conducted for heavy metals and other contaminants. Monitoring of agricultural chemicals needs to be done.
Succession: Combination of treatments used to set back succession (fire, mowing, girdling trees, fire wood removal, pulp wood sale drawdowns and herbicide).