For the second time, the frustrated juvenile bald eagle swooped down for its meal, only to be turned away angrily by its parent. Hungry and seemingly annoyed, it circled above the handsome older bird which, perched high on a forked branch of an oak tree overlooking the Hudson River's west bank opposite Tivoli South Bay, was devouring a small animal. What would the younger eagle do next? My kayak wobbled as I craned back to get a better snapshot of the unfolding drama with my inadequate little waterproof camera.
Tom and I had paddled south from the landing at Glasco, a small
community on the bank of the Hudson, earlier that misty November
morning. Most of the leaves had fallen and the air was quiet and
chilly. Eagles had not been sighted in this area before, according to
Dennis Mildner of the ecology field station nearby. Nevertheless Tom
Torkilson had no hesitation when he pointed out the shape perched in
the highest limbs of a tree.
"It's a bald eagle, Ian," he cried. "Look at its movements. It's feeding on something."
"A rabbit, from the looks of it," I replied.
Soon we spotted the second eagle on a nearby branch. Despite its considerable size, it was recognizable as an immature bird because it lacked the "bald patch," the national bird's characteristic white-feathered head. For a while, the young eagle seemed content to watch the parent consume its breakfast. Suddenly, however, it took to the air, circled, and then approached the bigger bird. With a flap and a fluster the parent drove the juvenile away. The older eagle continued to tear at flesh with its beak, holding the branch with one claw and the prey with another.
The young bird made another unsuccessful foray, then retired to a
different perch. From this vantage point, perhaps, it saw its chance.
Quickly it made a third attack, this time flying from a lower angle.
All of a sudden, both eagles were in the air! The parent had been
driven from its branch. A skirmish ensued, then parent and offspring
separated.
Unmistakably, the young eagle had something in its claw. It was the
remains of the meal, probably little more than a leg, but at least
something for breakfast! Both birds then disappeared into the trees.
Tom and I paddled on, feeling privileged to have been privy to this
domestic squabble, and to have glimpsed a little more of the natural
life alongside the Hudson River. Talking later to Dennis Mildner, we
learned that the immature eagle was probably only a few months old, and
that by November most youngsters should have learned to hunt for
themselves. Mildner speculated that the juvenile may have been born
late, perhaps in June or July rather than March or April. Late breeding
has been attributed by some to contaminants, notably PCBs. Bald eagles
have been the subject of intense study on the Hudson River,
particularly in the vicinity of Iona Island. For more than a century
bald eagles have been spotted in the winter months, but a sharp decline
in the species was observed during the early 1960s.
Now, it seems, a precarious recovery is underway. The Iona Island area
and the lower Hudson River have been included in the New York State
Department of Environmental Conservation's annual mid-winter bald eagle
aerial surveys since 1979. In eastern North America, bald eagles leave
their northern nesting territories annually during mid- to late fall as
lakes and river begin to freeze and typically move south to congregate
on wintering grounds where open-water foraging areas, daytime perches
and nighttime roosts are available and protected from human
disturbance. Although only small numbers of bald eagles use the area
annually, it has been determined to be one of only four regular and
essential wintering areas in New York.
Wintering sites like Iona are critical to deep-winter survival when
little open water is available for hunting. Brackish tidewaters and
river traffic normally keep some water free of ice all winter, and the
narrow curve in the river creates upwellings which apparently bring
weak-swimming fish like bullheads to the surface where they become easy
prey for bald eagles. The eagles also feed on bass, white perch, carp,
catfish and feral goldfish as well as mergansers, mallards, ring-billed
gulls, cottontail rabbits and even white-tail deer. The eagles perch on
the highest trees overlooking the river, fly over the water and return
to the same branches to consume fish that they have caught. Some take a
ride on ice floes, catch fish and return to the floe to feed. Survival
dictates that no energy is unnecessarily wasted.
Because of its importance, Iona's eastern side is closed to the
public during the months of December through March: it is an official
Winter Bald Eagle Sanctuary. Dennis Mildner and his colleagues at the
Hudson River Estuarine Research Reserve have solicited the cooperation
of HRWA members, both in observing the sanctuary and in reporting
sightings. They can be reached at (845) 758-5193.
Ian Giddy
December 29, 1995