[Mike]

http://www.sciencedaily.com/releases/2006/02/060221235120.htm
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
crabs.

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
species.

“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.”