Lago Swan NWR

Ecology & Conservation

• Habitat
• Wildlife
• Threats and Management  

Habitat 

Swan Lake NWR is divided into 5 major habitats: 1,000 acres of bottomland hardwoods, 3,840 acres of wetlands and moist-soil units, 2,075 acres of croplands, 3,050 acres of open water, and 600 acres of grasslands. The refuge lies in a glacial till plain, and underlying bedrock is primarily shale and coal with occasional limestone.  Most of the refuge is relatively flat. The refuge is subject to periodic flooding caused by the Grand River with a watershed of 7,900 square miles.

The bottomland hardwoods area is known as the Yellow Creek Research Natural Area. This special designation precludes habitat manipulation other than that wreaked by Mother Nature. The grasslands habitat consists of a 260 acre block of tall-grass prairie as well as scattered prairie plantings on crop field edges. Crop fields are planted on a rotational basis to provide food for wintering waterfowl.

Silver Lake, 3,050 acres in size, acts as a reservoir for spring and fall flooding of Refuge moist-soil units. Refuge moist-soil units are: Swan Lake (1,100 acres), South Pool (1,850 acres) and nine other units ranging in size from ten to sixty acres. Flooding of moist-soil units is accomplished through a gravity driven system of ditches and canals from Silver Lake. All wetlands are impoundments with draw-down capability through the use of screw gates. Units are drained into South Pool which feeds back into Elk and Yellow Creeks.

Wildlife

The Eastern Prairie Population (EPP) of Canada Geese is a species of special management concern for the refuge. The EPP used Swan Lake NWR as their main wintering grounds until the late 1980s. In recent years winter distribution of the EPP flock has shifted farther north. The average wintering flock between 1992-1997 was about 42,000 birds compared to a peak of 177,725 in 1976. Today we may see just a few thousand Canada Geese using the Refuge as a migration stopover site.

It is not uncommon for the Refuge to host up to 100,000 ducks, comprised mostly of dabblers, during the fall migration. Ducks as well as Canada Geese may over-winter on the Refuge during the mild winters. Birds often retreat to the nearby Grand and Missouri Rivers during cold snaps. Up to 150 bald Eagles may winter at the Refuge along with the waterfowl. Mallards and wood ducks are regular breeders during the summer months.

Threats and Management

Swan Lake National Wildlife Refuge was established by Executive Order 7563 on February 27, 1937, with instructions that “the primary purpose of the refuge is to provide nesting, resting, and feeding areas for migratory birds and other wildlife”. The refuge staff at Swan Lake is committed to preserve and maintain 5,000 acres of diverse Refuge wetlands in their existing or an improved state.

Swan Lake NWR is protected as a unit of the National Wildlife Refuge System in accordance with the National Wildlife Refuge System Administration Act (16 USC 668dd) as amended by the National Wildlife Refuge System Improvement Act of 1997. The refuge is managed by the Department of the Interior, U.S. Fish and Wildlife Service and designated as Swan Lake National Wildlife Refuge. There is a water management plan, a cropping plan, a grassland management plan and a land use plan. The plans are modified and or updated annually by the Refuge Manager. Swan Lake Refuge has cropping obligations as specified in A Management Plan for the Eastern Prairie Population of Canadian Geese.

Any or all of these projects and plans should positively affect the shorebirds that utilize the Refuge by providing more habitat and more actively managing to encourage shorebird use.

Susceptibility of flooding of all managed wetlands and croplands is the biggest threat to the Refuge that affects water quality and biodiversity. Our inability to control water depth precludes use of the Refuge wetlands by many species. Chemical runoff from agricultural fields upstream in the watershed is a potential threat to Refuge water quality. Constant siltation of Silver Lake is long term threat to the Refuge water quality and water supply.

Refuge access is highly controlled resulting in little human induced disturbance by shutting the gates from late October to the end of February. This keeps the interior portion of the refuge closed during peak migrations.

Management emphasis concerns all refuge wildlife, whether migratory or resident, and their respective habitats. The Wildlife Management Goal is to protect, restore and manage habitat for waterfowl, migratory birds, endangered and threatened species, and resident game, with emphasis on restoring and/or preserving pre-settlement type conditions.