Where Are the Ducks

By Andrew Raedeke and David Graber | January 2, 2006
From Missouri Conservationist: Jan 2006

“Where are the ducks?” hunters ask us each fall. “And what makes for a good season?” Yet most have theories of their own. Some of the competing ideas we’ve heard include:

“If we’d only have a dry year, then the ducks would be concentrated in the places that have water,” versus, “If we would only have a wet year, there would be more habitat available and more ducks.”

“Hunting would be better if we could hunt refuges and get the ducks to spread out,” versus, “We need more refuges in our hunting area to attract more ducks.”

And, “We have a hunting lease and can’t compete with public areas and their big refuges,” versus, “We’re lucky to have a duck hunting lease close to a Department of Conservation refuge—it provides a source of ducks.”

So which are correct? The above ideas stem from two opposing perspectives. One is that Missouri has reached its “carrying capacity” for migrating waterfowl. In other words, it has enough wetland habitat for the ducks that migrate through each fall. Hunters in this camp often blame poor duck hunting on refuges or the restoration of wetlands (private or public) that lure ducks away from their favorite hunting spots.

The other perspective is that Missouri has not reached its “carrying capacity” for migrating waterfowl. Hunters in this camp believe that if we restore more wetlands or create more refuges, Missouri will attract more ducks and have better hunting.

After hearing from hunters on both sides of the issue, we decided to take a more in-depth look at how restoring wetlands and adding refuges has affected duck hunting in Missouri.

Wetlands: Past, Present and Future

Missouri’s wetlands serve the vital function of providing migrating waterfowl a place to rest and replenish energy reserves lost in flight. This recovery takes time. To illustrate, a duck flying nonstop from North Dakota to Missouri requires about 14 days to recover the fat reserves expended in flight. If ducks lose too much weight in migration, they reach their southern wintering grounds in poor shape and are less likely to successfully produce ducklings the following spring.

Although wetlands in mid-latitude states are critical for migrating ducks, most of them have been destroyed or drained. Less than 15 percent of the historic wetlands remain in Missouri, Kansas and Illinois, compared to about 50 percent in the breeding grounds and wintering grounds. Wetland habitat from north to south now resembles an hourglass.

To the north, the breeding grounds in the Dakotas, Minnesota and Wisconsin are dotted with nearly 20 million acres of wetlands. Even more wetlands are found on the prairies in southern Canada.

The mid-latitude states of Missouri, Kansas and Illinois represent the bottleneck in the hourglass with only 2.3 million acres of wetlands. This region is bound by the Missouri River and its tributaries to the west and the Mississippi River and its tributaries to the east. States to the south still have 19 million acres of wetlands.

So what does this bottleneck and the loss of habitat mean for the millions of ducks that migrate south each fall? Missouri accommodates about 32 million duck-use days (a duck-use day equals the number of ducks times the number of days they are here) each fall. The region that produces the ducks that migrate through Missouri has a breeding population of about 19 million ducks. In a normal production year, a fall flight of about 38 million would be expected. If all of these ducks stopped in Missouri for just 10 days, we would support nearly 400 million duck-use days!

Of course, not all ducks from this region migrate over Missouri. But it does suggest that Missouri has much more potential to accommodate more than the 32 million duck-use days it now supports.

Effects of Adding Wetland Habitat

Another way to see if Missouri has reached its carrying capacity for migrating waterfowl is to review how ducks have responded to the restoration of wetlands in Missouri. In the last 15 years, the Department of Conservation has restored more than 25,000 acres of wetlands, and the Natural Resource Conservation Service (NRCS) has restored an additional 100,000 acres on private land. The ducks have responded.

The number of duck-use days on managed state and federal wetland areas in Missouri jumped from an average of 21.2 million in the 1970s to 32.1 million from 1994–2004. Hunters have reaped the benefits. Before these restorations, the statewide harvest topped 300,000 only once from 1961-1996. Since 1997, the harvest has never been below 300,000, and it frequently has topped 400,000. Missouri’s share of the flyway harvest has increased from about 3 to 4 percent to 6 percent.

But have these restorations been too much of a good thing? Have we restored so much habitat that new habitat is now pulling ducks away from existing habitat? This does not appear to be the case.

Eight of the top 10 counties for duck harvest in the 1960s were in the top 10 in the 1990s. The proportion of harvest on public and private land has remained steady over the last 10 years, with only 15 percent of the annual harvest occurring on Department of Conservation managed wetland areas.

In most regions where we restored wetlands and added refuges, harvest and duck numbers on the existing areas remained steady. The new areas have attracted more ducks to these regions. For duck hunters, this has translated into more hunting opportunity and improved harvest.

Wet vs. Dry Years

Wet years give us a glimpse of what might occur if we could restore more wetland habitat. In the fall of 1998, the Missouri River flooded in central Missouri and created an abundance of shallow water habitat in the region around Eagle Bluffs CA. Hunters reported excellent hunting on the habitat created by the floods, and Eagle Bluffs held a record number of ducks.

A similar set of circumstances occurred around Schell-Osage CA and Truman Reservoir during the fall of 2004. Timely rains caused Truman Reservoir to rise, creating an abundance of habitat. As a result, Schell-Osage held more ducks than it had in several years and hunters on nearby Truman Reservoir reported great hunting.

These cases suggest that ducks don’t just spread out from managed public wetlands when more habitat is available. The additional habitat actually attracts more ducks to the region and improves hunting for hunters on both public and private lands in the region.

Quality vs. Quantity of Wetlands

Hunters who feel we have too much habitat also point to the many ponds and reservoirs that have been built in the last 30 years. However, these lakes and ponds provide a very limited amount of food. Wetlands that have more food tend to attract more ducks.

Ducks require a diversity of food sources to obtain adequate amounts of protein, lipids, minerals and vitamins. Many native wetland plants supply ducks with these resources. Corn also can serve as an important source of food. It provides a great source of energy, but lacks other essential nutrients necessary for a duck to survive.

Managers strive to provide a variety of food resources. During a typical year, the Department of Conservation leaves fewer than 500 acres of flooded standing corn in refuges statewide and around 1,000 acres of flooded corn in wetlands that are hunted. Ducks use lakes, ponds and streams without food less frequently and for shorter periods.

The Role of Refuges

Decades of research have demonstrated that refuges provide essential undisturbed habitat for ducks to rest and replenish energy reserves. When ducks face too much disturbance they often leave an area entirely.

For example, in states without much refuge, over half of the harvest often occurs within the first 10 days of the season. Hunters in these states frequently talk about areas being “burned out” from too much hunting pressure. What past research doesn’t tell us is if we have reached the point where we have too much refuge here in Missouri.

To answer this question in Missouri, we examined the relationships among refuge size, duck numbers and harvest. The results indicated that areas with large refuges held the most ducks and supported the highest harvest.

The importance of refuges became more apparent when we factored in the additional “refuge” provided on areas that allowed only half-day hunting. Furthermore, the results suggested that if ducks don’t have adequate refuge, they will leave the area.

Our analysis also revealed that, at some areas, harvest was not as high as we expected based on refuge size. The harvest at Ted Shanks CA, for example, was much lower than our statistical model predicted. We expect that this result was due to the loss of bottomland forest and lack of food. The Department of Conservation is now aggressively working to restore quality habitat at Ted Shanks CA.

Strategies to Improve Success

The results of our study support the perspective that Missouri has not reached its carrying capacity for migrating waterfowl. We haven’t witnessed a decline in harvest at Department of Conservation areas when new areas were added nearby.

Department-managed wetlands still account for only 15 percent of the statewide harvest. During years when we have additional habitat due to wet conditions, we tend to have more ducks and better hunting.

We did not find any evidence to suggest that Missouri’s refuges are detracting from hunting. Instead, it appears that Missouri’s refuges are one of the major factors contributing to hunters’ success on both public and private lands.

So, if refuges and restored wetlands aren’t to blame, what is causing poor hunting in some areas? Weather, hunting pressure, food and refuge mainly influence which wetlands are attractive to ducks. We can’t control the weather, but we can improve duck hunting by limiting hunting pressure, growing quality food and providing adequate refuge.

When you’re getting ready for next duck hunting season, take a look at your favorite spots and see if they are providing all of these ingredients. Is there a refuge of 200 or more acres within 15 miles? Is there a diversity of food available? Is hunting pressure in your immediate area limited, such as by half-day hunting?

If the duck population is up next year, the weather cooperates and you’ve answered yes to each of these questions, you should be in for a good season and there won’t be any reason to ask, “Where are the ducks?” because you’ll already know.

This Issue's Staff

Editor in Chief - Ara Clark
Managing Editor - Nichole LeClair
Art Director - Cliff White
Artist - Dave Besenger
Artist - Mark Raithel
Photographer - Jim Rathert
Writer/editor - Tom Cwynar
Staff Writer - Jim Low
Designer - Susan Fine
Circulation - Laura Scheuler