[mou] FW: [PABIRDS] Questions about Raven Flocks (Fulton Co) 2/01

[Alt, Mark]

This is interesting about ravens in Pennsylvania, especially the last
comment. Good Birding.

-----Original Message-----
From: Bird discussion list for Pennsylvania
[mailto:PABIRDS@LIST.AUDUBON.ORG] On Behalf Of Scott Weidensaul
Sent: Friday, February 02, 2007 8:32 AM
To: PABIRDS@LIST.AUDUBON.ORG
Subject: Re: [PABIRDS] Questions about Raven Flocks (Fulton Co) 2/01

   In his wonderful book "Ravens in Winter," New England biologist=20
Bernd Heinrich found that winter raven flocks tended to be made up of=20
young birds, which use the force of numbers to overwhelm and displace=20
resident pairs from carcasses and other food sources. Vagrant=20
immatures and nonbreeders may also form winter roosts of up to a=20
hundred birds (raven roosts of more than 2,000 have been recorded in=20
the West), usually near a food source like a deer carcass.

   As for migration, the conventional wisdom is that ravens are=20
nonmigratory, although the fact that sometimes enormous numbers of=20
juveniles form communal roosts and flocks suggests they are, at a=20
minimum, dispersing from somewhere. Ravens are frequently seen at=20
hawkwatches up and down the Appalachians, but so far, no one that I'm=20
aware of has tried to determine if any of these birds are true,=20
regular migrants, if they're dispersing juveniles, or if they're=20
local birds simply using the ridges to moves across their often large=20
territories. (Some years ago I was building a database of known raven=20
nests, with the hope of one day wing-tagging chicks to follow their=20
fall movements via hawkwatchers -- an idea I've never had time to=20
implement.)

   In a 1922 paper on the breeding habits of the last ravens in=20
northern Pennsylvania, Richard Harlow said that "it will be but a few=20
years before it follows the Wild Pigeon into the list of extinct=20
Pennsylvania species." Nice to see how wrong he ultimately proved to=20
be.

   Scott Weidensaul
   Schuylkill Haven, PA




>On January 14th I had a fairly large flock of Ravens here in Clinton=20
>County.  There were at least 8 and possibly as many as 11.  (The=20
>flock was along a cut for a power line that curved and it was not=20
>possible to see the whole flock at once.)  The ravens weren't=20
>particularly vocal or active.  The just seemed to be hanging out=20
>together.
>
>Peace,
>
>Jeff
>
>Jeff Schaffer
>
>________________________________
>
>From: Bird discussion list for Pennsylvania on behalf of Dan Snell
>Sent: Thu 2/1/2007 9:39 PM
>To: PABIRDS@LIST.AUDUBON.ORG
>Subject: [PABIRDS] Questions about Raven Flocks (Fulton Co) 2/01
>
>
>
>Today during a Winter Raptor Survey, I had the good fortune to run into
a
>soaring flock of vocal ravens. At first I thought I had a kettle of
Turkey
>Vultures, but upon closer examination these were definately corvids!!
>Excited,  I stopped the car immediately, rolled the windows down- and
>listened...and we watched the aerial antics.
>
>There were a total of TWELVE Ravens: some were soaring extremely high
and
>moving quickly eastward, one Raven was chasing a Red-tailed Hawk (which
I am
>not sure why the hawk was in the middle of the kettle formation.),
flying at
>a lower elevation were three definate pairs (synchronized flying and
>tumbling).  The sounds we heard included the throaty gutteral call,
croaks,
>and also a few "bell" sounds.
>
>In Fulton County, I RARELY see a flock of this size. The site location
was
>along a high ridge road near the Maryland border. One side was a
forested
>precipitous drop to a creek (that feeds the nearby Potomac River). The
other
>side had  small hay fields with heavily forested mountains in the
backdrop.
>
>Seeing something like this made me wonder:
>Is anyone else currently seeing any amounts (flocks larger than two)
of
>ravens in PA?
>Did I just witness pair formation (like some sort of aerial turkey
lekking
>grounds) and the others were just driven away..
>Or maybe a local migration of Ravens just occurred......
>What do the birders in the northern tier of counties see with winter
>population dynamics of Ravens...
>
>Even though I should be working on "work projects", this really has me
>intrigued...
>
>
>Dan Snell
>Shippensburg, PA
>Southcentral Pennsylvania
>
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