Tag: cormorants

Population Control for Cormorants

  • Biologists Jim Farquhar and Mike Smith inspect the cormorant nests in the treetops. (Photo by Karen Kelly)

The pesticide DDT almost wiped
out the double-crested cormorant.
Now, the bird is thriving, and it’s
blamed for devouring fish in lakes,
rivers, and fish farms in many parts
of the country. Karen Kelly reports
on the struggle to share resources
with this unpopular bird:

Transcript

The pesticide DDT almost wiped
out the double-crested cormorant.
Now, the bird is thriving, and it’s
blamed for devouring fish in lakes,
rivers, and fish farms in many parts
of the country. Karen Kelly reports
on the struggle to share resources
with this unpopular bird:

(sound of clanking and birds)

Mike Smith eases a boat into the shallow water just off Little Murphy Island. It’s a tiny patch of sand and trees in the middle of the St. Lawrence River. It straddles the New York border with Canada.

Smith is a wildlife technician with New York’s department of environmental conservation. He specializes in cormorant management. That means he knocks down nests, breaks eggs, and – very occasionally – shoots them.

Before he even jumps off the boat, he starts counting the birds that are poking out of nests in the treetops.

“I see a few. I’m looking at their nests. We tried to have a zero percent successful reproduction rate.”

Smith counts maybe ten nests. They started with 150 or so in the spring.

There are tens of thousands of these birds. They spend their summers in the north. And in the winter, they go south where they raid fish farms.

Biologists estimate each bird eats a pound of fish a day. That can make a dent in the local fish population. The birds also strip trees of their leaves to create nests. And their guano ends up killing the trees’ root systems. That ends up driving out other animals that need vegetation.

Some people feel the birds should be eradicated. One group of anglers was even arrested for killing hundreds of them on Lake Ontario.

There are others, like the group Cormorant Defenders International. They feel they should be protected.

It’s up to biologists like Jim Farquhar of New York’s Department of Environmental Conservation to find the balance between human needs and cormorants.

Farquhar: “We have needs too, as people.”

Karen: “And we’re competing with them.”

Farquhar: “And we’re competing with them in some cases. Hopefully, if we can inject good science, we make good decisions as a result.”

The biologists’ biggest effort has been on Lake Ontario. They’ve been destroying nests there — and killing some adults – for ten years. Farquhar says they’re finally seeing results.

They’ve reduced the cormorant population on the lake by about two-thirds, and the fishing’s improved.

Now, the biologists are trying to have the same success on the St. Lawrence River. But they’ve only seen a 13% decrease in the number of cormorant nests and they’ve been doing it for four years.

Part of the challenge is that most of the birds live on Canadian soil where management is left to the landowner.

Local anglers like Steve Sharland of Ogdensburg, New York, are frustrated with the slow progress.

“They should eliminate them. They’re not a Northern New York bird and what they’re doing to our fisheries is a sin.”

That’s a common misconception. Actually, the cormorant is native to the region but few people have seen them in such large numbers.

Sharland says some people are so frustrated, they’ve been shooting the birds illegally. But Jim Farquhar believes those are isolated incidents.

“Mike just mentioned that we’ve got some black-crowned night herons nesting out here. It’s another species we’re concerned about, and one we’ve been trying to actively protect from the cormorants. So that’s a good sign.”

A good sign. But it’s another species trying to live on this small patch of land. And the biologists’ balancing act has become even more delicate.

For The Environment Report, I’m Karen Kelly

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Ten Threats: Botulism Kills Beach Birds

  • Interns for Presque Isle State Park in Erie, Pennsylvania walk along a Lake Erie beach picking up dead birds. (Photo by Lester Graham)

Researchers are beginning to understand what’s killing thousands of
Great Lakes shorebirds. It might be part of a larger problem indirectly
caused by humans. The Great Lakes Radio Consortium’s Lester Graham
reports:

Transcript

We’ve been bringing you reports from the series, ‘Ten Threats to the Great Lakes’ which is now looking at the threat to beaches. Our guide through the series is Lester Graham. He reports that scientists are beginning to understand what’s killing thousands of Great Lakes shorebirds. It might be part of a larger problem indirectly caused by humans.


Researchers are beginning to understand what’s killing thousands of
Great Lakes shorebirds. It might be part of a larger problem indirectly
caused by humans. The Great Lakes Radio Consortium’s Lester Graham
reports:


Along parts of Lake Erie, Lake Ontario, and Lake Huron, large numbers
of dead birds and fish are washing up on shore. If they’re left there, the
disease that killed them can be passed on to other wildlife. That’s why
park officials such as Mike Mumau at Presque Isle State Park at Erie,
Pennsylvania ask their staff to watch out for the dead carcasses.


“Our interns do a great job. They’re the eyes of the staff that are out. So,
there’s probably three to four days a week that they’re out on the
beaches, checking to see if they have anything.”


Since 1998, untold numbers of fish and sometimes hundreds of dead
birds a year have washed up on just these eight miles of Lake Erie beach.


Eventually, researchers figured out the problem: type “E” botulism. It
slowly paralyzes the birds until the respiratory system shuts down. Most
of them don’t make it that long. They get so weak they can’t hold their
heads up out of the water and they drown.


(Sounds of walking and shovel)


Leslie Jones and her fellow interns are headed out to an area to pick up
some dead seagulls on the beach.


“When we’re out here doing migratory bird studies, we might see some
and then we pick them up as soon as possible. A lot of times, we get
radioed from different people like lifeguards and they have us come out
and pick them up so that the disease doesn’t spread throughout the rest of
the ecosystem.”


They find five dead birds rotting on the beach. They bury the maggots
because they could carry the botulism toxin and other birds might eat the
maggots. They shovel the bird carcass into a black plastic garbage bag.


“If they’re very fresh, this one, obviously not very fresh, but, if we get a
fresh one, we actually freeze them and they’re sent off to be tested
botulism, but, something like this we’ll just bag up until we can get them
incinerated to get rid of all the disease.”


The fresh carcasses are shipped to the National Wildlife Health Center in
Madison, Wisconsin.


There, Grace McLaughlin is among the researchers who are beginning to
put the puzzle together.

Here’s what they think is happening. The invasive species zebra mussels
and quagga mussels create huge mussel beds that begin a complicated
biological phenomenon. Organic matter collects there, and then decays. It
lowers the oxygen level in the immediate area of the mussel beds. Type
“E” botulism spores occur naturally, but when the oxygen level goes
down, they begin reproducing like crazy. The waste they produce is the
toxin.


“That toxin will accumulate in the organic matter as well as in the water
in the immediate vicinity of the mussel beds. As the mussels do their
filter feeding, they will accumulate the toxin in their tissue. They are not
susceptible to the toxin. However, when the fish start coming down
there and eating the mussels, they become intoxicated, lose their ability
to swim properly and become easy prey for the birds that come in.”


The fish that feeds on the mussels the most is another invasive species,
the round goby. Researchers made the connection when they noticed the
botulism started being a problem shortly after round gobies arrived in big
numbers.


The type “E” botulism toxin has killed tens-of-thousands of birds such as
cormorants, terns, loons, ducks, and seagulls.


Back at Presque Isle State Park, Mike Mumau says it’s terrible to see so
many birds die.


“We just do our best on our end to stop the botulism cycle. When we
can, provide samples, and also, keep it a positive recreational experience
for all our visitors. They don’t want to see birds decomposing and
rotting out on the beaches, so we’re pretty diligent with that.”


Researchers say that’s about the best that can be done. Since ocean-
going vessels brought zebra mussels, quagga mussels, and round gobies
to the Great Lakes, all three of the invasive species have flourished. It
will likely be a long time before we’ll ever begin to understand the full
extent of the damage to the native wildlife of the lakes.


For the GLRC, this is Lester Graham.

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Cormorant Control Begins in Earnest (Part 1)

In many ways, the double-crested cormorant is a wildlife success story. The
birds were almost wiped out by pesticide exposure in the 1960’s. But in
recent years, they’ve returned in large numbers to prime fishing areas in
the Great Lakes and elsewhere. In fact, they’re so good at catching fish,
commercial fishermen have been affected. In the first of a two part series,
the Great Lakes Radio Consortium’s Karen Kelly found that the biologists who
protect these birds are also looking for ways to get rid of them:

Legacy Left by Cormorant Slaughter (Part 2)

The double-crested cormorant has been an enemy of fishermen for centuries.
They’ve eaten salmon on the Atlantic coast, catfish in Missouri and game
fish in the Great Lakes. Fishermen complain the cormorants are bad for
business. And last summer, fishing guides on Lake Ontario made their point
by killing more than two thousand birds. A year later, they’ve been caught
and arrested. In the second of a two part series, the Great Lakes Radio
Consortium’s Karen Kelly reports the effect of those killings is still being
felt:

Cormorant Control

In April, the U-S Fish and Wildlife Service denied a permit request
from New York State to kill three-hundred cormorants on eastern Lake
Ontario. The proposed management plan as well as previous killings by
individual sportsmen has Great Lakes Radio Consortium commentator Don
Ogden reflecting:

Cormorant Control

Federal fish and wildlife officials will most likely let New York state
reduce the number of double breasted cormorants on Lake Ontario… but
not by euthanizing the birds. The Great Lakes Radio Consortium’s
Elizabeth Christensen reports:

Managing the Cormorants

Wildlife officials around the Great Lakes region are struggling with
the issue of double-crested cormorant populations. There are questions
about the impact of the birds on sport fish and commercial fisheries.
New York State has asked the U-S Fish and Wildlife Service to approve a
new controversial plan for managing cormorants in eastern Lake Ontario.

Cormorants Slaughter Remains a Mystery

The shotgun massacre of nearly 9-hundred young cormorants on a Lake Ontario Island has prompted offers of rewards for information from the U-S Fish and Wildlife Service, and at least one animal rights group. State and federal agents have mounted what they term a "large and aggressive" investigation. The Great Lakes Radio Consortium’s Martha Foley reports: