Contaminated river causing empty nests
Bald eagle pair on Lake
Greenwood unable to hatch eggs
by Jackie Sheckler
from the Sunday Herald-Times, Sept. 7, 1996
CRANE - Admiral Halsey and Molly have moved three times, hoping the stork
will visit their nest. But their efforts have been for naught. The bald
eagles have been unable to hatch any nestlings. The eagle's eggs are contaminated
with PCBs. "The birds realize that something is wrong," said Lynn
Andrews, natural resources manager for the Crane Division, Naval Surface
Warfare Center. "But they must believe it has to do with their nest
because they building new ones."
Originally released at Lake Monroe as part of the state's program to
reintroduce eagles to Indiana, Molly and Admiral Halsey decided in 1989
callCrane's Lake Greenwood theirhome. For the past five years, Molly has
laid two eggs and sat on them like a good mother. Admiral Halsey also took
his turn on the nest when his mate wanted to take a break. It takes about
35 days for the eggs to hatch. But nothing ever happened for the two eagles.
"We let the birds sit on them for as long as 40 to 45 days and then
chased them off the eggs, Andrews said. "They were good parents".
Tests show that the baby birds died of embryo toxicity. Their development
had stopped at about four days. "This means there isn't a fertility
problem because there have been embryos in those eggs each year, said Dan
Sparks environmenatal contaminant specialist for U.S Fish and Wildlife Service.
Instead the embryos have died within the eggs. "The eggs do have
high concentrations of PCBs," Sparks said. As a result fish were tested
from the BDO-acre Lake Greenwood, where the eagles have built their nests.
"In 1994 when we had failed eggs three years in a row, we colleceted
fish out of Lake Greenwood," Sparks said. "But it turns out we
found no PCBs in the fish there, so the PCBs are coming from somewhere other
than Lake Greenwood. Eagles can easily travel 25 to 50 miles to feed, said
John Castrale non-game biologist with the Department of Natural Resources.
To try and track down the PCB source, researchers captured Admiral Halsey
and fitted him with a radio transmitter last year. "We really had hoped
to be able put the transminer on the female but they couldn't catch her."
Andrews said. The tratsmitter revealed that one of the feeding spots for
the male eagle was the White River in Greene County. The White Biver is
fed by Richland Creek, with possible drainage from PCB contamination at
Neal's Lanfill. Other PCB sites in Bloomington drian to Clear Creek then
Salt Creek and on to the East Fork of the White River. Neal's Landfill in
Owen County drains directly into the White River.
Both the White River and the East Fork of the White River have advisories
against eating the fish because of PCBs. The White Ri0ver has level 3 and
4 advisories - level 3 advises that people eat no more than one fish meal
from the river a month: level 4 advises no more than one every two months.
The East Fork of the White River has a level 5 advisory. "They don't
get any worse than that," Sparks said. "Basically it says do not
eat fish meals from here - ever."
But the two eagles cannot read fish warnings and eat from wherever they
find fish. However, PCB accumulation in an eagle is far heavier than in
people eating contaminated fish, Sparks said. "An eagle who eats fish
most of the time is a different scenario than a human who eats fish only
on occasion."
A second pair of eagles nesting at Lake Gallimore at Crane is not experiencing
the same PCB contamination, nor are others scattered throughout Indiana.
Currently the state has 15 nesting pairs, including three at Lake Monroe,
two at Patoka Lake, one at Lake Greenwood and one at Lake Gallimore. The
eagles take up residence aroumd a large body of water and usually don't
feed in the same areas as other eagles. The other set of nesting eagles
at Crane has successfully hatched five babies - tow 1994, one in 1995 and
two in 1996. The baby eagles were the first raised in Martin County in almost
a century.
As recently as the 1970s, eagles were rarely seen in the state. As in
much of the country, their number had been reduced by lack of habitat, huntng
and he widespread use of such pesticides as DDT. Officials say the federal
government's 1972 ban on domestic use of DDT started eagles on the road
to recovery. State and Federal efforts to preseve their habitat also helped
From 1986 to 1989, the Indiana Department of Nature Resources released
more than 70 eagle nestlings on Lake Monroe in an attempt to re-establish
nesting birds. The "hacked" birds were transported from nests
in Alaska, Wisconsn and Minnesota to a specially built tower at the North
Fork Refuge on Lake Monroe. The theory was that they would nest in the area
when mature. "Hacked" birds are the runts of three-eaglet nests,
which scientific evidence shows would have diminished survival chances if
left in the wild. The birds were taken from the nests at the appropriate
stage of their development, flown to Indiana and then reared in the tower
under as natural conditions as possible until they were ready to fly on
their. The results have been even more officials had hoped, said Castrale,
who is with thc Department of Natural Resources. But the problem with Molly
and Admiral Halsey has the department puzzled.
"It's a very unusual case," Castrale said. "All of our
other pairs have been pretty productive so we want to do more studies to
find out what's happening." |
