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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