BIRDER'S JOURNAL
November 18 , 2010

SUBJECT: Bald Eagles Hunting Coots & Playing "Coot Catch": Upper Mississippi River

eagle with coot

I wonder sometimes if we would have been better served with the turkey as this country's national symbol as Benjamin Franklin had suggested. Bald eagles do present themselves as a bold, fearless predator. They have a huge wingspan of 80 inches and talons sharp enough to pierce and grab their prey. Who in the world would want to mess with this raptor?

Let the truth be known however that while these birds do hunt live fish and other prey, they also are opportunistic feeders... or should I say... scavengers. They are always looking for a free meal! Not only are they looking for a free meal, they are thieves! Quite often they chase other eagles, stealing the prey from their talons or scaring the eagle into dropping their catch.

Sometimes even duck hunters are duped by opportunistic eagles. I recently had a conversation with a duck hunter on the river that told me of a story of how he shot a duck and by the time he started his boat to retrieve the duck, the eagle swooped down and stole the hunter's prize!

But although an entertaining story, most of the eagle's free meals this time of year are due to a class of parasites called trematodes that infect the exotic faucet snails now common on the pools located on the Upper Mississippi. These snails are a food supply for migrating diving ducks and some of these ducks become ill due to the trematodes ingested when they eat the snails.

The American Coot seem to be quite vulnerable to this parasite and during autumn on the Upper Mississippi, large rafts of American Coots feed on these snails. Some of these coots ingest high enough numbers of trematodes that within days, sometimes hours, the coots die from intestinal hemorrhaging.

Enter the Bald Eagle. Bald eagles being the opportunistic hunters that they are, feed on these dying or dead coots. Thankfully (from what we know) they do not suffer any ill effects from eating the infected coots.

Observing the feeding patterns of bald eagles can be a lesson in futility. Their feeding pattern vary greatly from day-to-day and year-to-year. Sometimes there can be hundreds of bald eagles feeding on coots, while the next day there is very little activity and numbers of eagles are down substantially. Where do these eagles go? My guess is they travel from pool to pool looking for the sick/dead coots or they just hang out along the bluffs with their stomachs full!

On a typical day that I do encounter these eagles hunting coots, mornings are usually a time for feeding while afternoons are set a side for a game of "Coot Catch". I honestly do believe they are playing games. Or at least, some form of agility training for the younger eagles. While adults do drop coots to other adults, it is often the juveniles doing most of the game playing in the afternoons.

During a chase, I have seen up to three successful drops/catches without the coot ever hitting the ground. Whatever the reason for this behavior, it is something to watch!

—Alan Stankevitz

bald eagle with coots

The above photo shows two juvenile bald eagles passing part of a coot from one to the other.

 

bald eagle eating coots

And...the catch!

 

 

 

 

Web design © 2007, Alan Stankevitz
All photographs © 2002-2007, Alan Stankevitz

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