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People often question where our wild ducks come from, and of course there's a simple biological answer – eggs! But those people are really asking whether the ducks hunted here and the ducks we see migrating through in spring and fall are "resident" ducks that were born and bred in Wisconsin, or are "migrants" that pass through Wisconsin on their way to breeding grounds in Canada.
Answering that question has implications for the management steps we use to maintain healthy flocks. First, it would help to know where the majority of ducks harvested during a given period of time were hatched. For example, if we harvest mallards and mainly hatch in the Canadian prairie country, we might be able to offer grater hunting opportunities than if the majority of those birds were hatched here. Similarly, if mallard reproduction is very low in the prairie country (as it was in the late 1980s), we might not need to cut back as much on our harvests here if our birds were raised in-state.
On the other hand, if most of our ducks are locally-raised, then we might be overharvesting when we offer liberal seasons as we did in 1997 and 1998. So it's very important to know where the ducks that we hunt are raised.
Likewise, it is important to know if the sources of ducks available to hunters change during the fall season. For example, if needed, we might protect local breeding mallards by restricting the bag limits early in the season and allowing normal bag limits later if we knew that was necessary. It would help to know if we need to reduce the harvest of local mallards or if these birds are available all fall and are harvested at t he same rate from early October through November.
Migration rates and harvest information also help us determine where to spend your dollars to enhance duck production. Currently about a third of the money we receive from the state share of the federal waterfowl stamp must go for habitat improvements in Canada. We want to ensure that those dollars are present were they will provide the greatest benefit to state residents. So we decided to review past research reports and do some additional studies.
To determine what proportions of the "northern" ducks come from Canada and from the United States, we study ducks' leg bands. Biologists annually capture a small sample of ducks in the summer and place small metal bands imprinted with coded information around one of their legs. The bands in no way interfere with the birds' survival. When researchers recapture these ducks in subsequent surveys or when hunters bag such ducks, we ask them to report the band information to the U.S. Fish and Wildlife Service. Past studies indicate only a third of the banded birds hunters bag are reported, and better accounting could greatly improve how we manage duck populations. To make reporting as convenient as possible, hunters can mail in the bands to the address provided or call a toll-free number (1-800-327-2263) which is staffed 8 a.m. to 4:30 p.m. Monday to Friday, with automated answering services on evenings and weekends.
Information from past U.S. Fish and Wildlife studies creates a picture of ducks typically hunted in Wisconsin as shown in this table.
* Others includes mergansers, goldeneye, bufflehead, ruddy ducks and scoters.
So mallards make up 42 percent of the total harvest and wood ducks 19 percent.
In Wisconsin, biologists band about 4,000 wild mallards annually and about 1,200 wood ducks each August and September. Other species are banded as well, but in far fewer numbers than mallards and woodies.
Without going into great detail, we estimate the origin of mallards taken by hunters by totaling information from recovered leg bands in a region. We form a weighted average based on our population estimates of each duck species in that region. This gives us a way to estimate information about the whole duck population based on the number and kinds of ducks harvested.
In past studies, the U.S. Fish and Wildlife Service summarized results for duck bands turned in following the hunting seasons from 1961-75. Those studies estimated 55 percent of the mallards harvested in Wisconsin come from the so-called Lake State Region of eastern Minnesota, Wisconsin, Michigan and northern Illinois. (Banding Reference Area 14). Nearly 19 percent of the mallards harvested in those years came from the evergreen forests of northern Ontario, northern Manitoba and northern Saskatchewan (Banding Reference area 7). A nearly equal amount (21 percent) came from the prairie regions of southern Canada and the Dakotas. (See our map of duck banding reference areas.)
A second study some years later (1975-84) produced similar results - about 63 percent of the mallards harvested here were raised in Banding Reference Area 14; 15 percent from the northern Canadian forests (Banding Reference Area 7) and 18 percent from the prairie pothole region. We collected leg bands during the last few years, but have not analyzed them yet to determine if local mallards represent a larger percentage of the harvest now.
The 1961-75 study provided other interesting information that we've summarized here. Percentages will vary a bit year to year due to different season dates, but we believe this still reflects where mallards originate that are found in Wisconsin from late September through the end of November.
Mallards raised here in the Lake States remain a very substantial part of the birds we see or hunt. By mid-November however, more of the birds moving through Wisconsin are primarily coming from northern Canada and to a lesser extent the prairie pothole country. Even in that later part of the season about a third of the mallards harvested come from Wisconsin and adjacent states. Fewer than two percent of mallards harvested during the fall are taken after the deer gun seasons begin in that week before Thanksgiving. The analysis shows that 36 percent of the ducks harvested in a given year are taken before October 13th and two-thirds of those birds were raised in the Lake States region.
Ron Gatti is a DNR biologist and landscape ecologist who researches farmland species of wildlife; Jon Berquist is DNR's migratory game bird specialist.