It soon became apparent, as we approached this small island
situated at the east entrance to "Death's Door," that several
hundred nesting herring gulls and double-crested cormorants had
taken over the island. Fortunately the beacon light in the tower
there is entirely automated and powered by solar cells situated
on the south roof of the old residence and light tower.
Dating back into the 1950's and 60's, double-crested cormorants,
the species of the interior of the US, were becoming more and
more rare on the Great Lakes to the point that they were listed
as an endangered species in Wisconsin in 1973. Several factors
brought about the decline of this once-abundant species,
especially pesticide build-up in their prey species of fish.
Their population began to gradually rise in the late 1970's.
Island nesting sites in Lake Michigan and Green Bay, including
Spider Island, Gravel Island and the Strawberry Islands began to
support more and more nesting pairs. So rapidly did their
numbers recover that the state DNR delisted these large black
birds in 1985.
It was in late September of 1992 that I estimated 4300
cormorants in one huge flock near the mouth of Moonlight Bay
north of Baileys Harbor. There was often a movement of dozens of
birds from the back of the slowly swimming flock to the front,
much frenzied activity accompanied by splashing and flailing of
wings. It was apparent that they were experiencing very good
fishing.
These strange-appearing prehistoric-like creatures are the
perfect example of gregarious birds. They feed, nest and roost
in large groups and seldom are far from land. So large are some
of their island nesting colonies that most plants, including
trees, have little chance of surviving due to the heavy lime
deposits from the birds' droppings. Needless to say, these are
smelly places due to the excrement, regurgitated fish and offal.
The long, powerful, slender hooked beak of this bird is
legendary. Commercial fishermen of this region, using pound nets
to fish for whitefish, have little love for the cormorants. The
birds are naturally attracted to the live-trapped fish, dive into
the water, slash the fish in their unsuccessful attempts to catch
the too-large prey and disfigure the fish to the point where they
often are not marketable.
Along with the great quantities of fish these birds consume are
those containing high levels of man-made toxins. So high does
the build-up of these deadly chemicals become in their bodies
that there have been observed numerous cases of nestling
cormorants having grotesquely-twisted beaks as
well as twisted legs and backward-facing feet.
Substantial nests of sticks, grass and seaweed are built by the
birds in early summer on the ground, rocks, islands, ledges, in
bushes and low trees and also on artificial man-made nesting
platforms constructed during the period when these birds were
considered to be endangered. From clutches of up to seven eggs,
incubated for about four weeks, hatch naked chicks. They will
remain in the nest for about six weeks and be flying when between
six to eight weeks old.
What a beautiful sight it is to see V's or long strings of these
strong fliers barely skimming the surface of the water. I have
learned to be skeptical of people reporting 20 or more loons in a
flock, necks barely sticking out of the water. Invariably these
loons turn out to be cormorants whose flight formations, observed
in low light conditions, can also be easily mistaken for
geese.
The double-crested name of our Wisconsin breeding birds comes
from small tufts of feathers above and back of each eye, seen on
both male and female birds during breeding season. These crests
are attained by birds when they are four years old. An
interesting fieldmark of an adult double-crested cormorant is its
orange extensible gular pouch extending behind and below the
beak.
Cormorants have unusual plumage in that it is not nearly as
waterproof as that of loons, ducks and geese. Having spent some
time under water they head for the nearest land where they
proceed to spread their wings to "dry out their sails," like wet
laundry being hung out to dry.
Cormorants are "snowbirds" in that they will migrate this late
fall to a warmer southern climate. Our friend, Tom Erdman,
banded a nestling in the lower Green Bay area in July of 1976.
The following December it was recovered in Louisiana indicating
at least where some of Wisconsin's cormorants winter.
If there is a trend occurring, I suspect that the double-crested
cormorant population is gradually increasing in northeastern
Wisconsin. Here is a fascinating bird whose role in nature is
little understood and, like many humans, appears to have a bad
side as well as a good side. (But who are we to tell?) One
might call it the Jekyll and Hyde of the waterbirds.
It was 33 years ago that I began photographing the lighthouses of
the Door Peninsula and nearby islands. Following a clearance from
the US Coast Guard headquarters in Milwaukee last week I was
finally able to get to Pilot Island, a lonely, isolated,
difficult-to-reach lighthouse that had eluded me for a long time.
This column appeared in the Door County Advocate on 06/13/1997.
© Copyright 1997 Roy Lukes. All rights reserved.
