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Main Forums => The Roundtable => Topic started by: Desertdog on May 16, 2009, 11:33:08 PM
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Sounds like a great case of unintended consequence. Save the eagles; who learned to love having those endangered species for breakfast, lunch, and dinner.
Flourishing eagles feast on Maine's rare seabirds
By CLARKE CANFIELD, Associated Press Writer Clarke Canfield, Associated Press Writer
http://news.yahoo.com/s/ap/20090517/ap_on_sc/us_predator_eagles;_ylt=AsBH.cHpYKfo_le_WJtOsu134T0D
PORTLAND, Maine – Bald eagles, bouncing back after years of decline, are swaggering forth with an appetite for great cormorant chicks that threatens to wipe out that bird population in the United States.
The eagles, perhaps finding less fish to eat, are flying to Maine's remote rocky islands where they've been raiding the only known nesting colonies of great cormorants in the U.S. Snatching waddling chicks from the ground and driving adults from their nests, the eagles are causing the numbers of the glossy black birds to decline from more than 250 pairs to 80 pairs since 1992.
"They're like thugs. They're like gang members. They go to these offshore islands where all these seabirds are and the birds are easy picking," said Brad Allen, a wildlife biologist with the Maine Department of Inland Fisheries and Wildlife. "These young eagles are harassing the bejesus out of all the birds, and the great cormorants have been taking it on the chin."
The recovery of the bald eagle population has been well-documented, growing from 400 pairs to more than 10,000 pairs in the lower 48 states since the 1960s. But the revival has changed the natural order of things in Maine and other states, threatening other bird species.
With more eagles around and fewer fish in the waters than in the past, young eagles are turning to other birds to satisfy their hunger. Eagles are opportunistic feeders and will go after the easiest prey they can find, bird experts say.
In Alaska, many eagles have shifted their diet from fish to seabirds. In the Midwest, they've been known to eat baby blue herons. And besides Maine's great cormorants, eagles are also feasting on baby double-breasted cormorants, gulls, eider ducks and even loons.
Nobody's raising a stink about the eagles' taste for double-breasted cormorants and gulls because those birds are so numerous and considered nuisances by many.
But the great cormorants are another matter, because their numbers in Maine are so small, said John Drury, of Vinalhaven, who's been counting seabirds on Maine islands for more than 25 years. Although the birds are widespread from Europe to eastern Canada, they are uncommon in Maine, which represents their southern range in the Northwest Atlantic.
Drury last summer counted only 80 great cormorant nests, the smallest number since 1984, the year after they were first spotted on Maine islands. Without protection, he fears the Maine population could be wiped out.
Governmental agencies and conservation groups have put countless hours and dollars toward protecting other seabird populations such as terns — but little has been done for great cormorants, he said.
"We like to have diversity of species," Drury said. "If we're going to spend all that time and energy to protect terns, then cormorants deserve as much attention."
At one time there were an estimated 50,000 pairs of bald eagles in the continental U.S. But their numbers declined from hunting and habitat loss. It was the widespread use of the pesticide DDT that almost did them in. DDT accumulated in fish, a major food source for eagles, which resulted in eagles laying eggs with weakened shells. By 1963, there were only 417 pairs of eagles left in the lower 48 states.
The bald eagle began a gradual recovery after it was listed on the federal Endangered Species list in 1967. DDT was banned in the U.S. in 1972.
There are now more than 10,000 pairs, according to the U.S. Fish and Wildlife Service. Maine's 500 pairs represent the largest population in the Northeast, up from less than 30 pairs in the 1960s. New Hampshire has about a dozen pairs and Vermont has one. Minnesota, Wisconsin and Florida each have more than 1,000 pairs of bald eagles, the agency said.
The bald eagle was taken off the federal endangered species list two years ago; Gov. John Baldacci is set to sign a bill this month taking it off Maine's endangered and threatened species list.
But all those eagles need to eat.
In the Midwest, eagles have targeted young blue herons, said Jody Millar, the national eagle recovery coordinator for Fish and Wildlife, based in Moline, Ill.
And in Alaska, researchers have documented a shift in bald eagles' diet from fish to marine birds that's linked to changes in the coastal ecosystem.
A growing number of killer whales caused a chain of ecological events that reduced the number of otters and amount of kelp providing habitat for fish, Robert Anthony reported in the journal Ecology. With fewer fish and baby otters to eat, eagles began raiding nests of other birds.
In Maine, eagles have been spotted eating loon chicks and have occasionally been known to carry off adult loons, said Sally Stockwell, director of conservation at Maine Audubon.
Off the coast, eagles have taken to eating all types of seabirds on rocky remote islands and ledges where, in years past, the seabirds didn't have any predators. If fish — the eagles' natural diet — were more plentiful, perhaps they wouldn't be so inclined to go after other birds, Drury said.
"They'll catch whatever is easiest to catch," he said. "There are more birds now and less fish."
Drury was on Seal Island last week to chase bald eagles away from cormorant nests. Besides eating the babies, eagles are driving the adults from their nests, leaving the eggs exposed to other predators, he said. The eggs will hatch in late May or early June, and the chicks will learn to fly by mid-August, he said.
Greg Butcher, director of bird conservation for the National Audubon Society in Washington, hasn't heard of the eagle resurgence affecting bird populations elsewhere, but said he wouldn't be surprised if it's happening. Whatever the case, it is sure to generate debate among the nation's millions of birders, he said.
"We're in an interesting age where most people think birds are either overabundant or too rare," he said. "It's hard to get it just right."
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Stop screwing with the environment and let nature take it's course.
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Those eagles had better behave before someone sics those brain-eating flies on them.
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Nature is a mother, ain't she ??
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Maybe if the eagles eat more birds, then there will be more fish.
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Maybe if the eagles eat more birds, then there will be more fish.
Sounds like nature at work to me.
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Next time someone wants to burn a flag give them a .22 and point them towards the nearest eagle.... same effect, but at least this way there is a bit of a positive outcome.
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Good idea. At least they will be violating a law that way.
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they are uncommon in Maine, which represents their southern range in the Northwest Atlantic.
Looks like their range is about to get a little smaller.
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"They're like thugs. They're like gang members. They go to these offshore islands where all these seabirds are and the birds are easy picking," said Brad Allen, a wildlife biologist with the Maine Department of Inland Fisheries and Wildlife. "These young eagles are harassing the bejesus out of all the birds, and the great cormorants have been taking it on the chin."
Mr. Allen, despite being a wildlife biologist, is apparently not very familiar with wildlife. Animals kill and often eat each other. That's what they do. Thugs and gangs choose to do bad things to their own species that are not necessary for survival. Eating what nature intended you to eat is not bad behavior.
Besides, I don't see any great cormorants on any seals throughout the US.
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Somehow I am not surprised that the do gooders ended up trading what is good for one species for another. They are always willing to trade the good of humans for the good of some critter.
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Saw an eage hit a seagull while I was driving over the Wabash River.
Just a cloud of feathers. Truly amazing. :O
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I wish we could get some eagles to eat some of the sea gulls down here. I hate those birds.
So were these sea birds in trouble before we came around and killed all the bald eagles? What did they do in 1619? Was there just more other birds for the eagles to munch on?
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I wish we could get some eagles to eat some of the sea gulls down here. I hate those birds.
So were these sea birds in trouble before we came around and killed all the bald eagles? What did they do in 1619? Was there just more other birds for the eagles to munch on?
What seems to be the likely cause of the decline of their main food source, fish?
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Does this mean we can start using DDT again?
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What seems to be the likely cause of the decline of their main food source, fish?
baby harp seals
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What seems to be the likely cause of the decline of their main food source, fish?
Globual Woerming ??
:rolleyes: :rolleyes:
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Globual Woerming ??
:rolleyes: :rolleyes:
If you like. I was wondering if there was another answer though.
Two posts attacking my question indicates something though.
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"They're like thugs. They're like gang members. They go to these offshore islands where all these seabirds are and the birds are easy picking," said Brad Allen, a wildlife biologist with the Maine Department of Inland Fisheries and Wildlife. "These young eagles are harassing the bejesus out of all the birds, and the great cormorants have been taking it on the chin."
Next thing you know, those eagles will be flying around in bandanas with Tec-9's and Glock Four-Tay's..... =D
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Two posts attacking my question indicates something though.
What do you feel it indicates?
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Well, I thought perhaps a careful re-reading of the article would answer my question, and I thought that perhaps I was wrong because of:
A growing number of killer whales caused a chain of ecological events that reduced the number of otters and amount of kelp providing habitat for fish, Robert Anthony reported in the journal Ecology. With fewer fish and baby otters to eat, eagles began raiding nests of other birds.
So I googled for that report and found:
Estes, J. A., * M. T. Tinker, T. M. Williams, D. F. Doak. Killer Whale Predation on Sea Otters Linking Oceanic and Nearshore Ecosystems. Science, Vol 282, Issue 5388, 473-476 , 16 October 1998.
Abstract: After nearly a century of recovery from overhunting, sea otter populations are in abrupt decline over large areas of western Alaska. Increased killer whale predation is the likely cause of these declines. Elevated sea urchin density and the consequent deforestation of kelp beds in the nearshore community demonstrate that the otter's keystone role has been reduced or eliminated. This chain of interactions was probably initiated by anthropogenic changes in the offshore oceanic ecosystem
So the quote from the article only covers Alaska so doesn't answer why eagles have shifted their food source in Maine. But that final sentence might well give lie to the notion that this is purely nature taking its course without human interaction.
Willing to be proved wrong, but I suggest that if low fish stocks are the reason that newly abundant bald eagles are predating upon other vulnerable species then we can't view that purely as nature abstracted from human causes taking its course if we are the cause of low fish stocks. So - are we?
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Well, I thought perhaps a careful re-reading of the article would answer my question, and I thought that perhaps I was wrong because of:
So I googled for that report and found:
So the quote from the article only covers Alaska so doesn't answer why eagles have shifted their food source in Maine. But that final sentence might well give lie to the notion that this is purely nature taking its course without human interaction.
Willing to be proved wrong, but I suggest that if low fish stocks are the reason that newly abundant bald eagles are predating upon other vulnerable species then we can't view that purely as nature abstracted from human causes taking its course if we are the cause of low fish stocks. So - are we?
Well, from that article it seems we are not hunting killer whales enough and their resulting over-population is destroying the habitat.
We need more killer whale hunting, then.
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We need more killer whale hunting, then.
That would be the logical conclusion of observing human actions causing unknown effects further on in the ecosystem.
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"They're like thugs. They're like gang members. They go to these offshore islands where all these seabirds are and the birds are easy picking," said Brad Allen, a wildlife biologist with the Maine Department of Inland Fisheries and Wildlife. "These young eagles are harassing the bejesus out of all the birds, and the great cormorants have been taking it on the chin."
Darwin always WINS!
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So the quote from the article only covers Alaska so doesn't answer why eagles have shifted their food source in Maine.
EASY PREY is probably the real answer. When it gets easier to fish than find the great cormorant chicks, then they will go back to fishing.
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That's probably partly true as they are opportunistic predators, but the article - USGS press release (http://online.wr.usgs.gov/ocw/htmlmail/2008/October/3/20081003nr.html) clearly links a shift in bald eagle diet to a decline in otter numbers:
The sea otter is a keystone species in near-shore coastal environments because of the pivotal role it plays in maintaining a healthy balance in kelp forests. By eating sea urchins – the biggest threat to kelp forests – sea otters controlled sea urchin numbers and kept the ecosystem in balance. This ensured these underwater plants could thrive and reach their maximum height of 250 feet.
Kelp forests provide habitat, shelter, and a buffer from waves and currents for numerous aquatic species. This marine environment also provided the bald eagle with a diet of marine fishes and sea otter pups.
Also note, and this is very interesting:
Although the diet of these bald eagles changed with the decline of sea otters, the scientists discovered that the birds actually produced more eggs and young, a fact that Anthony suggests may be a result of high caloric content in the eagles’ increasingly seabird-dominated diet.
So it may be that protections caused bald eagle populations to rise, then another effect down the chain caused them to shift their diet. When they did so along came increased reproductive success.
Good case you make there for managing fish stocks, as in not over-fishing or destroying fish habit.
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Okay, so we need to hunt killer whales and bald eagles ??
:rolleyes: ;/
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Okay, so we need to hunt killer whales and bald eagles ??
:rolleyes: ;/
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