Horseshoe crab & shore bird decline – Atlantic – 02/22/2006

  • November 23, 2013 at 1:50 am #1137
    Posted: February 21, 2006
    Horseshoe Crab Decline Threatens Shorebird Species

    Each year, the red knot, a medium-sized shorebird, makes a 20,000-
    mile round-trip from the southern tip of Argentina to the Artic
    Circle — one of the longest migrations of any bird. And each year
    from April to June, the red knot stops over in the Delaware Bay to
    feed on horseshoe crab eggs resulting from the largest spawning of
    horseshoe crabs found on the East Coast of the United States.
    Researchers from Virginia Tech and the New Jersey Division of Fish
    and Wildlife have documented a reduction in the number of red knot
    birds throughout the Delaware Bay tied to a decline in horseshoe

    The research will be reported in The Journal of Wildlife Management,
    in the article, “Horseshoe Crab Eggs Determine Red Knot Distribution
    in Delaware Bay Habitats,” by Virginia Tech fisheries and wildlife
    research scientist Sarah Karpanty, professor Jim Fraser, and
    associate professor Jim Berkson, New Jersey Division of Fish and
    Wildlife biologists Lawrence Niles and Amanda Dey, and Virginia Tech
    statistics professor Eric Smith. The article provides scientifically
    defensible information for wildlife management officials as well as
    for other members of the scientific community.

    During their Delaware Bay stopover, the red knot nearly doubles its
    body mass as it gorges itself almost exclusively on horseshoe crab
    eggs. The purpose of this feeding frenzy is to ensure that the
    shorebirds have enough energy to complete the trip north to their
    breeding ground in the Artic.

    However, due to horseshoe crab’s popularity as bait used by
    fishermen, the crabs appear to be in serious decline. At the same
    time, there has been a great reduction in the total population of
    red knots, the report notes. “The number of horseshoe crab eggs was
    the most important factor determining the use of the beaches by red
    knots. The availability of horseshoe crab eggs was even more
    influential than the presence of human disturbance, predator
    occupation, and availability of other types of food,” says Karpanty,
    a post-doc in the College of Natural Resources.

    The red knot’s dependence on the horseshoe crab for survival has
    attracted the interest of local, state, and international wildlife
    management officials and researchers. Due to the red knot’s unusual
    migratory and eating behaviors, scientists from as far away as
    Australia frequently travel to the Delaware Bay to study this rare

    “Biologists with the Delaware and New Jersey divisions of fish and
    wildlife have been very helpful during this project, and they
    welcome researchers from all over the world,” says Fraser. “We hope
    to see collaborative efforts like this continue so that we can learn
    how to better manage wildlife resources like the red knot and
    horseshoe crab.”

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