Evaluation of Blue-winged Teal Production on Private Lands in Wisconsin

A Proposal for a Research Partnership

What is the Problem?

Blue-winged teal are small, dabbling ducks that were the most abundant duck species breeding in Wisconsin as recently as the 1970s. However, since then teal populations in Wisconsin have declined 60%, an average of 3% per year, while mallard populations have more than doubled. During the same time in our neighboring state of Minnesota they have seen a similar mallard population increase but no blue-winged teal population decline. In the rest of North America, mainly the western prairies, mallard and teal population trends mirror one another and were recently at record high levels. Something different is happening to blue-winged teal in Wisconsin compared to the rest of the country and compared to our own mallards. It is likely that the population is declining from problems on the breeding grounds in Wisconsin rather than on migrational-wintering areas because populations from other regions, which share migrational-wintering areas, are not declining.

The vast majority of blue-winged teal in Wisconsin are produced on private lands, yet we know little about their productivity and survival there. We have only studied nesting teal on public lands in Wisconsin, where we have found good nest success. But teal face a different environment on private lands in southern Wisconsin, with alfalfa agriculture and fewer wetlands and grasslands.

What can be done?

A focused research study is needed to look at components of blue-winged teal population dynamics. We need to determine what aspect of the blue-winged teal life cycle is causing their population decline so that management can address the responsible factors.

The Graph below illustrates trends in duck abundance from 1973 to 2003
The yellow line represents Mallard populations
The light blue line represents Blue-winged Teal populations.

The study objective will be to directly estimate the productivity and survival of teal on the private landscape of southern Wisconsin. Radio telemetry is the most cost-effective method to estimate the following parameters for population modeling:

• preferences among wetland types for teal breeding pairs,
• preferences among landcover types for teal nesting,
• survival of teal nests from initiation to hatching among available landcover types,
• preferences among wetland types for teal brood-rearing,
• survival of teal ducklings from hatch to fledging,
• survival of adult teal hens during the breeding season.

Methods to study blue-winged teal recruitment will follow those developed for mallards in the Prairie Habitat Joint Venture (Ducks Unlimited, Canada) and used for mallards in the Wisconsin Private Lands Mallard Study (Wisconsin DNR) and the Great Lakes Mallard Study (Ducks Unlimited) recently completed. Blue-winged teal hens will be captured on wetlands when they first arrive in the spring using live-hen decoy traps. The captured hens will be fitted with small radio transmitters to monitor their movements throughout the breeding season, locate nesting attempts, and evaluate productivity and survival. Study sites will be located in the south-east quarter of Wisconsin, the region with the highest density of breeding blue-winged teal and highest priority for duck management in the state. Two sites will be studied in each of 2006, 2007, and 2008 with sites chosen to contrast the abundance of grassland each year. Forty teal hens will be marked with radio transmitters in each site, for a total of 240 radio hens during the study. Teal breeding populations will be censused each spring in each site from a helicopter to relate breeding pairs with grassland and wetland abundance.

What will be Produced?

This research will produce the first estimates of blue-winged teal recruitment parameters from Wisconsin that will be used to model our teal population dynamics. This model will explain why teal are declining in our state, but not elsewhere. The model will determine if the problem is low survival of adult hens, nests, broods, or a combination of these so that waterfowl managers can address the cause of the problem. This study will test our assumption of management for blue-winged teal (that grassland abundance limits teal recruitment), by comparing teal recruitment and survival between sites of high and low grassland abundance. This study will also develop a spatial model of blue-winged teal related to habitat types that will be used to guide management for teal within our state.

Why is this of Interest to You?

Blue-winged teal have dropped from the first to third most abundant duck species breeding in Wisconsin over the past 30 years. Blue-winged teal were the second or third most common duck shot in Wisconsin during the 1970s and now are fourth or fifth on average. Blue-winged teal have been identified as a species of greatest conservation need in Wisconsin for statewide planning and management. Science-based Management and Adaptive Management of our waterfowl resources both involve periodic evaluation of our management through research to determine how well it is working for the resource. The decline in populations of this small duck, which was such an abundant bird in our state marshes, is cause for concern to all who enjoy our wetland ecosystem.

If you would like to help or get a detailed proposal of this effort or get information on how to contribute a tax-deductible donation to the Wisconsin Private Lands Blue-winged Teal Study, please contact:
Ron Gatti
Waterfowl Research Biologist
Wisconsin Department of Natural Resources
1350 Femrite Drive
Monona, WI 53716
(608) 221-6348