Scaup (ducks) declining in Iowa – 04/03/2004

  • September 30, 2013 at 6:48 pm #429

    KEOKUK – Don’t be too surprised if you happen to spot a lime
    green, fluorescent orange or bright red duck swimming across your
    favorite wetland this spring.

    According to Louisiana State University wildlife research
    assistant, Mike Szymanski, the kaleidoscope-colored ducks are all
    part of an ongoing study designed to provide answers as to why
    populations of lesser scaup are on the wane. Known to most duck
    hunters as bluebills, lesser scaup are an important waterfowl species
    of the Mississippi Flyway.

    But while most duck species have shown healthy increases during
    the past decade, overall scaup numbers have shown an alarming
    decline. Although no one can say why scaup populations are falling
    off so rapidly, finding the answers may depend in part on keeping
    track of color-coded bluebills as they travel to Canadian breeding

    “This study will ultimately involve hundreds of people from
    Louisiana to Canada,” Szymanski said. “Currently, we are (bait)
    trapping, banding and color marking as many migrating lesser scaup as
    we can get our hands on.”

    The capture efforts are focused on the Mississippi River at
    Keokuk, where large numbers of the ducks stage during spring and fall
    migrations. With this year’s spring migration currently reaching its
    peak, scientists hope to capture and color mark between 3,000 and
    5,000 of the northbound ducks. As the birds disperse across Iowa and
    points beyond, researchers are relying on public sightings to help
    unravel the mystery of scaup migration.

    “What we are attempting is to document migration corridors and
    rates of movements from Keokuk to the breeding grounds in the boreal
    forest region of western Canada,” Szymanski said. “It’s possible that
    during the first half of the spring migration, a majority of scaup
    may visit the Dakotas. Later in the migration, more birds may travel
    north across Minnesota.

    “At this point, we don’t know the exact routes they travel, and
    visual sightings will play a key role in providing that information.
    What we’re really looking for is the when and where of scaup

    What researchers do know is that when northbound scaup arrive
    at Keokuk, they are in excellent body condition. However, as the
    migration continues across Iowa many of the birds begin to lose
    weight. Biologists say the weight loss could result in decreased egg
    production, reduced survival of adult females, and lower population

    “At this point, no one can say for sure why scaup are losing
    weight as they travel across Iowa,” Szymanski said. “It could be
    food; it could be parasites; it could be contaminates. Once we have
    those answers, we can begin working on a solution.”

    During the next two summers, biologists plan to sample wetland
    feeding grounds in Iowa, Minnesota and North Dakota. Researchers will
    be looking at the abundance of invertebrate marsh life (the primary
    protein source for migrating scaup), testing for chemical pollutants
    and measuring the level of sedimentation due to agricultural runoff.
    “There is strong evidence that migrating scaup are missing some
    important forage. It may be related to invertebrate abundance which
    could be related to water quality,” Szymanski said. “During the next
    two years we plan to look at habitat conditions across those areas.
    We’ll also continue to monitor the body condition of migrating scaup
    and see how that matches up against historical data.”
    Public sightings are important to project success. Observations
    of color-marked scaup can be reported via the Internet at or by phone at (888) 646-6367.

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