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 In this Section:  In the Spotlight News


List of "In the Spotlight" Features

Tracking Greater and Lesser Scaup


The population of Greater and Lesser Scaup has declined by 50% since the 1980's. Dr. Scott Petrie, Director of Research at Long Point Waterfowl and Wetlands Research Fund in Ontario, Canada studies the cause of this diminishing population.

Greater and Lesser Scaup are two species that are similar in their appearance, habitat, and size. Both species winter primarily along coastal regions of North America and migrate north to Alaska in the spring to breed. Hundreds of thousands of Greater and Lesser Scaup use the Great Lakes to feed and refuel during their journey.

Despite the large decline in the scaup population overall, the Great Lakes region has seen a substantial increase in number of scaup stopping over during their northward migration. Dr. Petrie and his colleagues believe the reason for the increase is the large supply of zebra mussels in the Great Lakes. Zebra mussels are an exotic species, introduced to the Great Lakes region in 1986 when a ship from Europe released its ballast water into Lake St. Clair. The ballast water contained the larvae of the zebra mussel which quickly spread throughout the Great Lakes region, changing the entire ecosystem.

Click here to see where they are! Zebra mussels have little competition in North America. Therefore, they quickly increased in number and spread throughout the Great Lakes. Zebra mussels are filter feeders, which means that they feed on small plants and animals that float in the water column. A single zebra mussel can filter up to one liter of water a day. In addition to food, zebra mussels take in any contaminants in the water, which can build up in their tissues.

The Great Lakes ecosystem is affected by water pollution from industry, including fossil fuel burning power plants. As a result of burning fossil fuels, the metalloid selenium is released into the environment. Selenium is a naturally occurring element that is necessary in small amounts in the diet of many birds. However, selenium can become toxic in large amounts. Zebra mussels take in and store selenium when they filter water for food. Waterfowl, including Greater and Lesser Scaup eat zebra mussels and they accumulate the toxic selenium in their tissues at potentially toxic levels. Scientists believe that high levels of selenium may cause the reproductive system in birds to fail. This could mean an end to offspring and could possibly be contributing to a decline in Greater and Lesser Scaup populations. Dr. Petrie and his colleagues continue to study populations of Greater and Lesser Scaup on the Great Lakes to see if selenium has an effect on their health or reproductive success.

Dr. Petrie tracks 18 Lesser Scaup and 2 Greater Scaup. The birds are captured and an internal transmitter is surgically implanted into the abdominal cavity of the bird. The procedure takes about 45 minutes and is performed by a specialized veterinarian. Once the transmitter is in place, Dr. Petrie can track the movement of the birds and determine where they winter and breed, when they visit the Great Lakes to eat, and how long their migration takes.

Signals of Spring students can use Dr. Petrie's satellite data to determine which major wetland areas, in addition to the Great Lakes, the scaup use to refuel during their migration between their wintering and breeding areas. Students can also compare the speed of the spring and the fall migrations. Keep an eye on the scaup as they continue their northward migration!

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