Low spring waterfowl numbers reflect drought conditions

DNR Report

Madison – State breeding duck numbers are lower than average this spring due to severe drought conditions across northern Wisconsin and fewer seasonal wetlands observed in southern Wisconsin, according to waterfowl biologists.

"Year to year, local and regional variations in wetland habitat and breeding ducks is part of the natural cycle in the world of wetland wildlife," said Kent Van Horn, DNR migratory waterfowl biologist.

"There has been less seasonal wetland habitat available in Wisconsin during our 2009 and 2010 surveys, but that's balanced by more wetland nationwide during the same period in the prairies states. Since ducks are migratory birds, they have learned to move to the water and adapt to annual differences in breeding conditions."

Three primary sources of information on yearly waterfowl breeding conditions are used to determine the fall seasons for Wisconsin. So far, wildlife managers only have data from the Wisconsin-based survey.

"We've completed the annual Wisconsin Breeding Waterfowl Survey," Van Horn said.

A cooperative survey of Canada geese, the Mississippi Valley Population Breeding Survey, organized by the Ontario Ministry of Natural Resources, has been completed, but results were not yet available as of press time for this issue.

The final piece is the U.S. Fish and Wildlife Service breeding survey for the northern United States, Canada, and Alaska. That information is expected in the next few weeks and will form the framework for the 2010 fall seasons.

Results of the state waterfowl population survey will be posted on the "Waterfowl in Wisconsin" page of the DNR website.

Duck outlook

Waterfowl breeding areas in Canada this spring had fair to very good conditions, with smaller areas of poor habitat. Breeding is expected to be good overall. Precipitation and wetland habitats in the Dakota prairies for 2010 were good to very good. Minnesota had dry conditions and below-average wetland numbers similar to Wisconsin. Breeding duck numbers for Minnesota are expected to be similar to last year and below average. In North Dakota and South Dakota, duck numbers and production should be average to good.

Despite better-than-normal winter precipitation in Wisconsin, spring came early and was dry in many areas. At the time of the Wisconsin survey – late April to early May – the state was very dry, particularly in the north where severe drought conditions exist and many lakes are at all-time low levels.

Across the state, spring 2010 was drier than 2009 and drier than average. Wetland numbers were 59 percent and 47 percent below average in two northern survey regions. In the two southern survey regions, wetland numbers were 37 percent and 26 percent below average.

"We have since had good rain and wetland conditions improved across most of the state, particularly in the south," Van Horn said. "Ducks that nested should have fair to good brood habitat, but it looks like some ducks went looking out of state for water, particularly blue-winged teal."

The four most abundant ducks in the state harvest are mallards, wood ducks, green-winged teal, and blue-winged teal. Van Horn said many of the ducks shot in Wisconsin are raised in the state, in contrast to other states that rely more heavily on birds raised in the prairies or boreal forests of Canada.

"These are population estimates – not exact counts – so changes of near 20 percent up or down in the estimates each year may not reflect any real change in the actual population," Van Horn said.

The 2010 mallard estimate of 198,242 is essentially unchanged from the 200,497 estimate in 2009 and remains about 9 percent above the long-term average (37 years). Mallards contribute to nearly 40 percent of the state harvest in Wisconsin. Overall, the breeding population of mallards appears to have ranged between 200,000 to 250,000 in recent years. Van Horn expects average production and fall mallard numbers.

In 2010, the estimate for wood ducks is 106,785 – similar to the 2009 estimate of 113, 523. Because state woodie numbers have increased significantly from the early years of the survey, the 2010 estimate remains 41 percent higher than average.

The bluewing breeding estimate of 50,188 is a big drop from the 2009 estimate of 112,792 and is well below average. While conditions suggest that a decline in the number of blue-winged teal breeding in Wisconsin is real, biologists believe that the early spring reduced the ability to see teal and exaggerated this low population estimate, Van Horn said.

This news is in contrast to the previous six years when state breeding estimates were above 100,000. It is also in contrast to the continental blue-winged teal population that has been near historic high populations at over 6 million breeding birds from 2007-09. Blue-winged teal are known to move around the continent in order to find the best water for breeding, and a dry Wisconsin this spring offered poor habitat, Van Horn said.

The total state breeding duck population estimate of 386,501 is down 23 percent from 2009 and is 12 percent below average. With mallard and wood duck estimates similar to 2009, the decline was heavily impacted by the blue-winged teal estimate. If the rainfall patterns continue to improve, wetland conditions should help to hold Wisconsin ducks into the fall and attract migrants from areas of the continent that experienced better breeding conditions.

"It is important to remember that wetlands are dynamic systems that experience wet and dry periods," Van Horn sai. "The dry years are important to the long-term health of these habitats but can have significant short-term impacts on wildlife associated with those habitats. As a result, wetland-dependent wildlife such as ducks normally experience cycles of high and low populations. It is important to protect the wetlands and associated habitat during dry periods so that when the rains return, so will the breeding duck numbers."

Canada goose outlook

"There are two populations of Canada geese that represent most of the geese in Wisconsin during the fall hunting season. The average over the last several years has shown the hunting harvest split roughly 50:50 between these two populations," Van Horn said.

Resident giant Canada geese nest in Wisconsin. The spring population estimate of 165,853 is up 12 percent from 2009 and is twice as high as average. Factors that likely contributed to this increase in the resident goose population include good production in 2009, a low Wisconsin harvest in 2009, and an early spring in 2010.

"We expect an abundant Canada goose population this fall, particularly for the early September season," he said.

By federal rule, the early goose season harvest must remain over 90 percent resident giant Canada geese. The season is scheduled early to target this population.

The second Canada goose population is the Mississippi Valley Population, which is made up of slightly smaller birds that nest along the coast of Hudson Bay in northern Ontario and migrate through Wisconsin and other Midwestern states. The breeding survey data are not yet available for this population, but early indications are that the breeding should be average to above average.

"These preliminary numbers indicate a mix of conditions. We will not know for sure what this means for the season structure until after the Mississippi Flyway Council meeting at the end of July," Van Horn said. "As we do each year, the public will have opportunities to provide input on waterfowl hunting seasons during our meetings and hearings. These public meetings are also a great opportunity to hear the latest on waterfowl management and population status. We'll take the public input to the Natural Resources Board along with a season structure proposal for approval on Aug. 11," he said.

The Mississippi Flyway Council, which is made up of waterfowl specialists from the states of Alabama, Arkansas, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Ohio, Tennessee, and Wisconsin, and the Canadian provinces of Manitoba, Ontario, and Saskatchewan, will meet later this summer to advise the U.S. Fish and Wildlife Service on waterfowl conditions before the USFWS sets a framework under which states and provinces can set waterfowl seasons.

Following the flyway council meeting and after the USFWS sets a season framework, public hearings on Wisconsin's waterfowl seasons will be held in August. The final Wisconsin seasons will be set by the NRB at its Aug. 11 meeting.

The DNR's proposed waterfowl seasons will be online at the end of July on the "Waterfowl in Wisconsin" pages of the DNR website.

The pre-flyway meeting will be July 12 in Portage. The post-flyway meeting will be July 31 in Wausau.

Categories: News Archive, Waterfowl

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