If you have a copy of the 2nd Atlas of Breeding Birds you can find
substantial information about crow populations in Maryland.
In the second atlas American Crows were found in 17 more blocks than in
the first atlas; Fish Crows were found in 76 more blocks, an 8% increase in
blocks. Looking at the Breeding Bird Survey trend graph for American Crow
it shows a significant drop in 2004 when West Nile Virus first affected the
population significantly. The same graph for Fish Crow shows only a minor
blip in 2004 to interrupt the species' steady growth over the past four
decades of surveys. If you read the text, particularly the last paragraph
for each species, Walter Ellison presents factual information about
research which supports the relative effects of the virus. His final
statement is: "It is possible that Fish Crows derived a temporary benefit
via less competition and less nest predation when their larger relative
declined".
But that is only one piece of the puzzle. The rise of the Fish Crow goes
back many years. In the mid 20th century the Fish Crow as a breeding bird
was almost unknown in the Piedmont away from the Potomac and Monocacy
valleys (see Stewart and Robbins 1958). Today it has spread throughout the
region.
All of the statements that have been made recently are based on
anecdotal observations but may be supportive of the facts. Draw your own
conclusions.
On Tue, Apr 9, 2013 at 1:11 PM, <pobrien776...> wrote:
> Fish Crows are the last to abandon the White Flint roost in the spring and
> the first to begin using it in the fall. So the birds passing through your
> neighborhoods lately are mostly Fish Crows. Aside from that, I have
> noticed that Fish Crows seem to be more numerous in recent years and may be
> breeding in suburban neighborhoods. Time for my afternoon nap.
>
> Paul O'Brien
> Rockville, Mont. Co., MD
>
>
> -----Original Message-----
> From: Clifford Comeau <cliffcomeau...>
> To: Janet Millenson <janet...>
> Cc: mdbirding <mdbirding...>
> Sent: Mon, Apr 8, 2013 7:32 pm
> Subject: Re: [MDBirding] Un-American Crows
>
> Yes, I have noticed more Fish Crows than usual, and fewer American.
> Have the American's become quiet and the Fish's more noisy?
>
> Cliff Comeau
> Gracefield Road
> Silver Spring, MD
>
>
> On Mon, Apr 8, 2013 at 5:52 PM, Janet Millenson <janet...>wrote:
>
>> Lately it seems the only crows calling around here are Fish Crows. The
>> scarcity of American Crows strikes me as unusual. Anyone else noticing this?
>>
>>
>> Janet Millenson
>> Potomac, MD (Montgomery County)
>> <janet...>
>> ----------------------------------------------------------------
>> "Look at the birds!" -- Pascal the parrot
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>>
>
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--
Bob Ringler
Eldersburg MD
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