Arrival of Spring Signals Return of Beeping Hens Ducks Unlimited Studies Nesting Ducks

Ducks Unlimited
Tuesday, 19 March 2002

Are waterfowl populations at risk because of changes on the landscape? Possibly, says DU. To know for sure, scientists are using tiny transmitters to track the daily movements of 600 mallard ducks as they mate and nest.

The study, launched in March, 2001, represents the most comprehensive effort yet to study mallard ducks in the Great Lakes states. Tina Yerkes, a DU research scientist, is overseeing the initiative and comparing the results to a parallel study undertaken in the prairie pothole region of western Canada known as "the duck factory." "Our knowledge of waterfowl behavior is based primarily on the duck factory. We're venturing into the Great Lakes region to learn more about how ducks are responding to a variety of circumstances that don't exist in the prairies, including urban expansion," said Dr. Yerkes.

The Great Lakes region represents one of the most important breeding grounds for waterfowl. Production has grown at a rate of approximately 5% a year since 1966, but scientists have noticed a recent leveling off and possibly a drop in production. According to Dr. Bruce Batt, chief biologist at DU, the mallard study is a "top research priority" because habitat and waterfowl management are grounded in detailed knowledge of species and their distinct habitats.

The study will be conducted in the Great Lakes states of Ohio, Indiana, Illinois, Wisconsin, and Michigan. The first phase involves trapping hens. "Unlike geese, which mate for life, ducks tend to separate after they mate. Each spring, there is a rush by the ducks to establish breeding territories which they defend against intruders of the same species," explained Dr. Yerkes. In order to trap hens, the research team sets up a live decoy hen in an open cage. "Once a wild hen detects another hen infringing on her territory, she swims into the trap to chase off the intruder," explained Dr. Yerkes.

Once trapped, the hen is brought into a special surgery room, where she is anaesthetized and prepared for a surgical procedure in which a radio device is implanted into her abdomen and she is released to the area where she was trapped. "Because the devices are small, similar in size to a lipstick case and weighing less than five percent of total body weight, the hen is unaware of the device," said Dr. Yerkes. The scientists do their best to keep pairs together, often trapping male ducks even though they are not part of the study.

The tracking devices enable the research team to glean data about the daily movements of the waterfowl, without disrupting their behavior. Each hen, emitting a unique frequency, will be tracked daily from a truck-mounted antenna. The findings will assist in long term conservation planning. "The results of the study will provide the critical data needed for waterfowl management in the Great Lakes states," said Dr. Bob Hoffman of DU's Great Lakes Regional Office. "We hope to learn more details about the habitat conditions that are most conducive to successful reproduction. We suspect that human induced factors, like sprawl and subsequent wetland degradation and loss, are being brought to bear, in combination with natural factors like weather and the amount of nesting cover available to the hens," said Dr. Hoffman.

The study, expected to cost $1.3 million dollars, involves many partners including the Upper Mississippi River/Great Lakes Joint Venture of the U.S. Fish and Wildlife Service, the Wisconsin Department of Natural Resources, the Michigan Department of Natural Resources, the Ohio Department of Natural Resources, Division of Wildlife, the Indiana Department of Natural Resources and several private foundations, including the Winous Point Marsh Conservancy, The Bruning Foundation, and the Christel-DeHaan Family Foundation. The joint enterprise will take place on ten sites in various areas in the Great Lakes. This year, there will be three active sites, located in Shiocton, Wisconsin, North of Battle Creek, Michigan and the North East corner of Indiana.

For more information, or to contact Ducks Unlimited, see their website at: www.ducks.org