blowing like this," Holt said, "you can gawddam forget that
John B. Holt, 40,
and Sergej Postupalsky, 45, have been banding eagles together since 1967. When
they started out, Postupalsky was already something of an eagle expert, having
begun his Michigan studies several years earlier. A resourceful field man and
meticulous scientist, he required a climber for his banding work because he
couldn't even stand on a step-ladder without getting dizzy. Holt was an expert
climber with plenty of experience banding owls and hawks, but he didn't know
much about eagles or the towering trees in which they nest.
"He made such
a fuss about the wind his first time up," Postupalsky recalls, "I knew
right away I was going to have to find another climber." But Holt stayed up
there long enough to band the birds, managed to descend without incident, then
inquired blandly, "Well, where's the next tree?"
The two have been
taking their spectacular act from one tree to the next ever since, hiking and
boating and driving over thousands of wild miles in upper and lower Michigan,
battling mosquitoes, flies, engine trouble, bad weather, nasty swamps, rugged
roads and, once in a while, each other. For seven or eight weeks from late May
to early July, working from dawn until dark, they submit to a cruel regimen of
cold wieners, warm beer, inelegant accommodations, fatigue and, in Holt's case,
the very real possibility of a serious accident. All of this to fasten, each
year, aluminum bands on the legs of five or six dozen young eagles, few of whom
survive to maturity.
The point is to
learn a few facts about a creature that is more familiar to most Americans than
any other bird except the English sparrow. Over the years the bald eagle has
been enlisted to help merchandise everything from tires and tobacco to NASA's
first moon landing and at least one professional football team. Despite this
visibility, the eagle isn't very well known in a scientific sense. Thus,
Postupalsky looks for answers to some very basic questions. How long do bald
eagles live? What do they eat besides fish? Where do the ones that migrate go?
How well is the species reproducing? It's slow work because nothing is usually
learned about a banded eagle until it dies, and not even then unless its
numbered band is returned to the U.S. Fish and Wildlife Service, which tells
Postupalsky where it was found, when and under what circumstances. So far, only
about 70 bands out of 750 have been recovered.
Postupalsky is confident enough in his findings to refute some common
misconceptions about the bald eagle. For one thing, the bird isn't strictly a
fish eater, as many believe. It's an omnivorous predator that goes after
anything it can handle, including ducks, snakes, rabbits and other small
mammals, not to mention northern pike and muskellunge. The eagle is also a
scavenger that feeds on everything from deer entrails left by hunters to road
remarkable eyesight, great size and tremendous range, the bald eagle is an
efficient hunter, but it isn't infallible. It misses its target from time to
time, sometimes ending up in the water and having to swim ashore using its
wings as oars. It also sometimes overestimates its own strength, killing
creatures with its enormously powerful talons that it can't lift with its
wings. Stories about eagles flying off with 20-pound lambs are greatly
exaggerated. An eagle, which weighs around 15 pounds, can't fly for any
distance carrying much more than half its own weight.
And despite their
menacing reputation, eagles aren't aggressive toward people. Indeed, they not
only won't attack, they won't even defend their nest and young against human
harassment. If that harassment continues for any length of time, they may
abandon the nest altogether. Some amateur naturalists interpret this as
"cowardice," but that, Postupalsky emphasizes, is an anthropomorphic
misreading. "It makes evolutionary good sense for eagles to flee rather
than fight," he says.
It's uncertain how
long bald eagles live, but Postupalsky believes they can survive and continue
to breed for at least 20 or 30 years. Because the mortality rate for young
eagles is about 80%, one pair must produce 10 or 12 chicks just to replace
themselves. Eagles don't necessarily have a brood every year. But because a
breeding pair mates for life, the chances are good that they will be able to
reproduce themselves—as long as nothing interferes with the breeding process.
Unfortunately, there has been a great deal of interference lately.
most direct way to interfere is to shoot, poison, trap or otherwise destroy an
eagle. This is illegal, but it's still being done and quite possibly on a scale
larger than the two or three arrests every year in the U.S. indicate. But the
main reasons why the bald eagle is in such big trouble today are habitat
destruction and poisoning by pesticides—in the past, mainly DDT. Even now
residual DDT in the fish it eats impairs the eagle's ability to reproduce. Once
eagles nested by the thousands all across the lower 48 states. Today only about
1,200 breeding pairs are left, though more fly down for the winter from Canada,
where they are still quite plentiful. The species is classified as endangered
in most states and threatened in several, including Michigan, which presently
has 80 to 90 breeding pairs.