Agassiz National Wildlife Refuge

Getting to Know Minnesota Moose, Bitterns, & More

Winters at Agassiz National Wildlife Refuge in northwestern Minnesota can be severe. Temperatures have been known to drop as low as 47 degrees below zero, and fewer than a third of the days in a year are frost-free.

But even so, an exciting variety of animals make this refuge their home year-round, and many more spend their summers here or pass through during spring and fall. The refuge offers a changing but always spectacular wildlife scene for visitors, who make the trip to this 61,500-acre sanctuary not far from the U.S. border with Manitoba, Canada. It is a place where the thrill of sighting a moose is likely, particularly during late summer or fall.

Situated in the basin of ancient Lake Agassiz, a glacial lake 700 miles long and 200 miles wide that was created when the ice cap melted 10,000 years ago, Agassiz NWR is now part of the wetlands that remained after the lake gradually drained into the Great Lakes.

The refuge is in the drainage basin of the Red River of the North, which empties into Lake Winnipeg in the Canadian province of Manitoba. It is one of ten national wildlife refuges within the state of Minnesota.

The flat terrain ensured the formation of the lakes and marshes that attracted wildlife in great abundance to the Agassiz area. The water that spread over the landscape, however, also covered rich, fertile soil, which the increasing number of farmers wanted for crops. In 1909, therefore, the largest single public drainage project in the United States was started, and, by 1933, $1 million had been spent on the scheme to make the wetlands arable.

But the plan never worked. The construction and maintenance of the drainage ditches, called judicial ditches because they were court ordered, were to be paid for by assessments on the land owners who benefited.

The assessments proved too high, Marshall County could not collect the delinquent payments needed to pay off the loans, and county bankruptcy loomed. The county turned to the state of Minnesota for help, and the state agreed to pay off the county debt if the federal government bought the land for a refuge.

In 1937 President Franklin D. Roosevelt established the Mud Lake Migratory Waterfowl Refuge, the state condemned the privately owned land, and the refuge was bought for $6.14 an acre.

The name was later changed to Agassiz NWR in honor of Louis J. Agassiz, the Swiss-American geologist who did pioneering work in the 1830s on glacial movements and deposits and for whom the glacial Lake Agassiz was named.

The wetland habitat was restored in the late 1930s by the Civilian Conservation Corps, which built the dikes and most of the 19 pools.

Flood waters are also stored in the pools, not an insignificant role since in the refuge water is merged from two major rivers and 455 miles of public drainage ditches. In a wet year, all pools are filled, and sheets of water a half mile wide will breech the dikes and flow out of Agassiz Pool, the refuge's largest at 10,000 acres.

Dave Bennett, assistant refuge manager and overseer of refuge maintenance operations, says that flood damage to dikes has been averted through constant maintenance by experienced workers.

The 125 miles of dikes are regularly checked for "dig outs" by muskrat and beaver. "One of these at the wrong spot and you're done," says Bennett. The essence of water management at Agassiz is annual maintenance of the dikes, he says, adding that to "do no maintenance, you would lose the refuge in five years."

Ensuring wetland habitat for wildlife inside the refuge while drying it out for farming outside will not get easier. Instead of paying farmers in a flood year for crops they can't grow, says Bennett, the county plans to assess farmers for straightening ditches so that more water can be moved.

That means, of course, that downstream flooding will be worsened. And Bennett says that no one is thinking about sediment buildup in refuge pools and about what less holding capacity can mean in future flood events.

Prescribed burning is also needed on the refuge, especially to maintain a mosaic of willows for moose browse. Burns in the fall are used to eliminate growth while those in the spring are used to stimulate—a process according to Bennett, that should be applied to 12,000 acres a year but is done on as few as 3,000 acres.

Complicating and frequently curtailing the maintenance work is the acute shortage of money and staff, a problem plaguing not only Agassiz but the entire refuge system. Maintenance of nearly 100 square miles of refuge, let alone the operation, repair, and servicing of heavy equipment, is expected from a total of only two maintenance workers, down from four.

Willows and aspens are favorite browse for moose, the refuge's largest resident. Moose (Alces alces) are adapted to cold climates, and Agassiz is at the southern boundary of its Canada and Alaska range.

As many as 400 of these big animals were in the refuge during the 1940s, a population that grew from dwindling numbers in the 1920s, when moose hunting had to be banned in Minnesota to help protect the survivors.

Surveys, however, indicate that another decline has occurred during the past 25 years. The population at Agassiz dropped to an estimated 71 animals at the end of 1996, the lowest on record. The shooting of moose in the refuge had to be banned again in 1993 although limited hunting outside the refuge is allowed in some years.

The losses triggered a pilot research study at the refuge in 1995, done in cooperation with the Minnesota Department of Natural Resources, on how to equip the big animals with radio transmitters so that dead animals could be located and examined for the cause of their deaths.

The pilot study evolved into a major three-year project that refuge manager, Maggie Anderson, says has produced an unbelievable show of public support and high media interest.

Pace of the project seems to almost outdo the unusually energetic Anderson, who is now soliciting grant funds for an Internet site to expand the mass communication about the moose project.

Fundraising for the research is undertaken by Anderson and Minnesota's DNR through the Moose Mystery Challenge in which 40 local businesses and organizations have so far joined by each putting up $400, which is matched by funds from a conservation organization called Wildlife Forever.

The funds are also supporting an outreach effort in local schools to acquaint children with moose and the plight they are suffering. Students in 70 classes at 16 schools have adopted radio-tagged moose in the Adopt-A-Moose Program, which Anderson says is becoming a logistical challenge because more and more schools want to participate.

Adoption and birth certificates are issued to the classes, which are also given monthly updates on the status of their adoptees. Classroom presentations and videos are used to teach students about moose and their habitat needs.

According to Anderson, a class in Roseau, MN, got to write the first obituary in November for a radio-collared animal that it had just adopted. She says that the death of an adopted moose provides an opportunity to teach how moose fit into the web of life of predators and decomposers.

Captured with a net gun fired from a helicopter, adult moose are equipped with solar powered ear-tag or collar radios by a specially trained crew from a company based in Salt Lake City. Capture of new-born calves is easier; they just lay down when approached. Signals emitted by the radios permit the moose to be tracked by an antenna mounted on the roof of a vehicle.

The tracking is done mostly by graduate student, Eric Cox, who is working toward his doctorate in wildlife and conservation from the University of Massachusetts. If the radio signal changes to its mortality mode, Cox is alerted that the animal has been still and could be dead and that a search is required to find the animal for further examination and possible necropsy.

Refuge biologist, Gary Huschle, remains puzzled over the losses, but results so far are redirecting the research. Huschle says that parasites and disease may be having more impact than previously thought.

Liver flukes, a parasitic flatworm, and brain worm together with pneumonia are being found in the dead animals. Because moose-borne parasites are not unusual, Huschle is wondering what other environmental factor may be causing a higher susceptibility to the presence of the parasites and the incidence of pneumonia. No evidence of predation has been found.

The researchers have observed that, whereas 90 percent of radio-marked calves reached six months of age, only 20 percent survived longer. Of the adult animals sampled, the adult survival rate is higher but only 73 percent over a two-year period.

These results have caused the researchers to monitor a larger group of adults and to suspend the marking of newborn calves.

During the spring of 1997, 69 cows were either radio marked for the first time or recaptured for new radios and blood, hair, and fecal samples. Twenty of these cows were captured on private agricultural lands, and Anderson says that nearly everyone of the 160 landowners contacted gave permission for the helicopter captures. Cox is now monitoring 78 calves and adult cows.

Moose are just one of 49 species of mammals found at Agassiz NWR. Two resident packs of gray timber wolves, black bears, white-tailed deer, bobcats, fishers, and otters are among them. An additional 12 species of amphibians and nine species of reptiles are also recorded residents of the refuge.

Bald eagles, 17 species of breeding ducks, and Canada geese, that peak at 10,000 in September, are among the 280 bird species documented at the refuge.

Mallards will peak in October at 15,000, and by November fewer than 20 species remain in the frozen habitat. Nesting birds include bald eagle, huge colonies of Franklin's gull, eared and western grebe, black-crowned night heron, and double-crested cormorant. In 1995, 17 drumming ruffed grouse were spotted but only one short-tailed grouse was seen.

The American bittern is also a common nesting bird at Agassiz, although it is on the Audubon Society Watch List and is a Minnesota species of special concern because of its continent-wide decline.

No major studies of the bittern had ever been conducted until 1994, when a continuing study of its life history was launched cooperatively by the refuge and nearby St. Cloud State University in hopes of identifying threats to the bird's protection.

More than 11,000 people go to Agassiz each year to observe wildlife, to learn more about it, or to hunt white-tailed deer, permitted seasonally. Trapping is allowed by permit. Both hunting and trapping are considered necessary population-control measures in the absence of natural predation.

Since 1976, 4,000 acres of refuge have been officially designated a wilderness area and are thus off-limits to entry by anyone, including refuge staff, using mechanized means. The area is the western-most black spruce-tamarac bog in Minnesota and contains two lakes that were formed by pre-settlement deep-peat fires.

Surrounded by a "sea of agriculture" as manager Maggie Anderson describes it, Agassiz NWR functions as a wildlife oasis. Given that so much natural habitat has been turned over to development, even in areas like outlying northwestern Minnesota, places like Agassiz NWR have taken on a crucial role in conserving the wildlife that is essential to a healthy ecosystem of which, of course, humans are a part.

Visitors to Agassiz NWR can easily see the habitats that typify the refuge from County Road 7, a 13.5-mile public road that crosses through the refuge from its western to eastern boundary.

If one is lucky, one might even see a moose or two in the willow thickets or drinking from the ditch along the road especially in early morning or late afternoon during late summer or fall. The moose in the photograph was near the road and the picture was taken from inside a vehicle.

The county road passes an observation platform at Lansing Parker Pool and leads to refuge headquarters and the entrance to Lost Bay Habitat Drive. Most refuge auto drives are called wildlife drives, but Agassiz's habitat drive appropriately reflects what is sure to be seen rather than what might be seen. Interpretive signs on the drive relate the importance of the habitat characteristics to the wildlife that depends on it. A hiking trail adjoins the drive, which is open in the spring as early as weather permits and remains open through October.

A 100-foot-high former fire tower offers grand views of the refuge landscape. A key to the tower must be obtained from refuge headquarters. Forgetting to return it is virtually impossible because the key is attached to a moose-antler key ring as a not-so-subtle reminder!

Visitors should check with refuge personnel at headquarters for advice on what can be expected to be seen and where best to see it.

Nature books, refuge T-shirts, and travel mugs are now available at the retail shop just opened in the exhibit area of the headquarters as a satellite of the Tamarac NWR Interpretive Association. Managed by office manager Beulah Wikstrom (the shop was her idea), she hopes volunteers will eventually become involved in its operation.

Motels and campgrounds, including a city-operated facility with hookups for trailers and motor homes, are available in Thief River Falls for overnight stays, 23 miles southwest of the refuge.

Additional Information

Directions: From Thief River Falls, MN-32 north approximately 12 miles to County Route 7 and refuge directional sign, right (east) about 11 miles to refuge headquarters on left.

For more information, please contact:

Agassiz NWR
RR 1 Box 74
Middle River, MN 56737-9653

From Refuge Reporter, an independent quarterly journal to increase recognition and support of the National Wildlife Refuge System

Published: 29 Apr 2002 | Last Updated: 15 Sep 2010
Details mentioned in this article were accurate at the time of publication


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