The Birds of North America account lists the following. In all cases, wide ranges are shown, with males heavier than females when noted.

Double-crested - "Regional differences are large and no data are available from the West coast and Alaska, where largest birds occur. Mean mass of small southeastern birds is scarcely half that of northern and western birds and the extremes span almost a threefold range (1 to 3 kg)." Total range (but with no birds from the Pacific): 1.0 - 3.0 Kg

Pelagic - Total range: 1.3 - 2.4Kg

Brandt's - Total range: 1.4 - 2.7 Kg.

So around here, the biggest cormorants are probably Double-crested males and the smallest cormorants are probably Pelagic females, with a mismash of all 3 species in the middle.

== Michael Hobbs
== Kirkland, WA
== http://www.marymoor.org/birding.htm
== birdmarymoor at verizon.net
----- Original Message -----
From: Kenneth Brown
To: tweeters U. wash.
Sent: Wednesday, October 31, 2007 6:22 PM
Subject: [Tweeters] Re: Question on Cormorants Weights


Wondering about cormorant weights listed by Sibley in his guide
to the birds. Double-crested, 3.7, Pelagic 3.9 and Brandt's 4.6lbs. The later two seem about right, but I am wondering if
the D.C. weight is incorrect.

The Audubon Encyclopedia list D.C. at 6, Brandt's 5.5 and Pelagic
3.5 to 5.5. Harrison states male is larger than female with no
weights included.

Secondarily, what is the difference in weight between respective male and felmales, and are weight differences with a species
individual or dimorphic? The last few years I have tried to include
weights of like species in our Tacoma birding class. It is very
helpful to know Lesser Yellowlegs weigh 76 gms. while Greaters
are at 170 gms.

Any help on these birding questions is appreciated.


Ken Brown
kennethwbrown at hotmail.com
Port Orchard, Wa.




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