[CT Birds] Bald Eagles vrs Great Cormorants

Boletebill boletebill at yahoo.com
Tue Feb 23 14:53:39 EST 2010


Hi all.
 
  Without drifting over into wild unproven speculation (and keeping in mind that Bald Eagles are great opportunists) we may be witnessing a shared behavioral trend among young BE's that have discovered that big, slow, water-logged adult Great Cormorants are an easy target in winter and offshore breeding colonies in Maine an easy target for GC chicks.
 
Bill Yule
 
"For those who hunger after the earthly excrescences called mushrooms."

--- On Tue, 2/23/10, Glenn Williams <gswilliams9 at yahoo.com> wrote:


From: Glenn Williams <gswilliams9 at yahoo.com>
Subject: Re: [CT Birds] Bald Eagles vrs Great Cormorants
To: ctbirds at lists.ctbirding.org, "Boletebill" <boletebill at yahoo.com>
Date: Tuesday, February 23, 2010, 2:31 PM


Bill,

In both cases, the Great Cormorants were not holding fish, just going about their business.  It seemed that the intent was to kill the cormorant though I guess the possibility of trying to get the cormorant to regurgitate food cannot be ruled out. Neither my wife nor I could recall seeing a Bald Eagle going after something so big.

Glenn Williams
Mystic  

--- On Tue, 2/23/10, Boletebill <boletebill at yahoo.com> wrote:

> From: Boletebill <boletebill at yahoo.com>
> Subject: Re: [CT Birds] Bald Eagles vrs Great Cormorants
> To: ctbirds at lists.ctbirding.org, "Glenn Williams" <gswilliams9 at yahoo.com>
> Date: Tuesday, February 23, 2010, 12:45 PM
> Thanks Glen for your
> observation
>  
> This is really interesting. For years we've seen
> Bald Eagles diving on great Cormorants when they surface
> holding a large fish to swallow. I always assumed when I saw
> an eagle dive on a GC in the water that the eagle was trying
> to make the Cormorant give up a captured fish.  I
> don't assume this any more.
>  
> So it would appear that those water-logged feathers
> that allow Cormorants to dive deeper than other birds have
> their drawbacks...like a slow take-off after fishing...and
> BE's have tuned in to that drawback.
>  
> Bill Yule
> 
> "For those who hunger after the earthly excrescences
> called mushrooms."
> 
> --- On Tue, 2/23/10, Glenn Williams
> <gswilliams9 at yahoo.com> wrote:
> 
> 
> From: Glenn Williams <gswilliams9 at yahoo.com>
> Subject: Re: [CT Birds] Bald Eagles vrs Great Cormorants
> To: ctbirds at lists.ctbirding.org, "Boletebill"
> <boletebill at yahoo.com>
> Date: Tuesday, February 23, 2010, 12:20 PM
> 
> 
> Bill,
> 
> This past week while birding the Connecticu River from Eli
> Ferry Road to Gillette's Castle, my family and I watched
> a sub-adult Bald Eagle attempt to take a Great Cormorant on
> the water and later two sub-adults doing the same thing at a
> location further north.
> 
> Glenn Williams
> Mystic
> 
> --- On Mon, 2/22/10, Boletebill <boletebill at yahoo.com>
> wrote:
> 
> > From: Boletebill <boletebill at yahoo.com>
> > Subject: [CT Birds] Bald Eagles vrs Great Cormorants
> > To: ctbirds at lists.ctbirding.org
> > Date: Monday, February 22,
>  2010, 9:04 PM
> > This is not a sighting report but an
> > observation.
> >  
> > As I reported Friday Great Cormorants turned up on
> the
> > lower CT River in visible numbers suddenly after an
> almost
> > total absence earlier.  This weekend 30-40
> GC's were in
> > their usual haunts between Essex and Deep River.
> >  
> > Greg had made reference to GC predation by Bald Eagles
> in
> > Maine so I looked into that report and the article
> was
> > highly publicized and sensationalized but it looked as
> if
> > there was something significant going on there. It
> seems as
> > if BE's are flying out to offshore breeding
> colonies of GC's
> > and preying on chicks.  What struck me the most
> about this
> > report was the quote by the interviewed biologist
> that
> > described the eagles as "THESE YOUNG EAGLES"
> are like
> > "thugs", etc. He seemed to be making a point
> that they
>  were
> > not ADULT eagles but sub-adult eagles. This
> description
> > struck a memory chord in me about an two incidents
> from last
> > year and something I saw this week.
> >  
> > Since Wednesday there's been a cohort... (I'm
> not sure this
> > is the right term but it sounds more professional
> that
> > "gang")...there's been a cohort of 6 or
> 7 sub-adult BE's on
> > the river between Hamburg Cove in Lyme and North Cove
> in
> > Essex.  They all hang out together and have been
> giving
> > great performances and interactions for the tour
> boats. On
> > Thursday and Friday there was still ice on North Cove
> and at
> > one point 5 of these birds were on the ice together
> eating a
> > large dark bird. I couldn't see what the bird was
> but it
> > brought me back to last year when there was a similar
> cohort
> > of 4 sub-adult BE's and twice, that is two
> separate
> > occasions, we saw all 4
>  sub-adult BE's eating an adult GC on
> > an ice floe. Clearly one or more of these young eagles
> had
> > killed the GC dragged it on the ice and ALL 4 were
> feeding
> > on it. This happened not once but twice. This has led
> me to
> > ponder whether or not there are records of
> co-operative
> > hunting among sub-adult BE's?
> >  Could it be that these "gangs" of
> young eagles, like
> > "thugs" in the words of the Maine biologist,
> are working
> > together to take down GC's?  I've never
> heard of anything
> > like this.  I've heard of this with Harris
> Hawks but not
> > with Bald Eagles. Fascinating stuff though.
> >  
> > I'd be interested if anyone has any ideas about
> this
> > possibility.
> >  
> > Thanks.
> > Bill Yule
> > Lyme, CT
> >  
> >  
> >  
> > 
> > "For those who hunger after the earthly
> excrescences called
> >
>  mushrooms."
> > 
> > 
> >       
> > _______________________________________________
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> 
> 
> 
> 
> 
> 
>       






      


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