Counting large numbers depends on the situation. Birds flying, yikes, I use
a multiple of 10's by group density and then count them individually as they
stream by. Ducks or other sitting large numbers I do counts by 25's
density, by that I mean I find the densest clusters, count 25 and do a
visual on about how much space that takes. Then I adjust it for less density
by slightly increasing the space which I count as 25 birds. I was trained
in this by using photographs of known numbers of ducks and estimating the
numbers that were projected on the wall in our class. At first all of us
students were pretty low, but after several slides we got closer. Our final
exam was a picture of 130,000 shorebirds and our counts ranged from 110K to
145K, which is still within 20%. One student, not me, got 130,450 which
earned her a pitcher of beer from the rest of us. Counting large numbers is
hard.


>From: "Martyn Stewart" <mstew at naturesound.org>
>Reply-To: mstew at naturesound.org
>To: <n.lander at comcast.net>, "'Tweets'" <tweeters at u.washington.edu>
>Subject: RE: birding counting questions
>Date: Mon, 5 Apr 2004 07:17:58 -0700
>
>Nancy, absolutely yes, obviously if you hear many then it is a guess, say
>you hear a Crow for instance and then around a 100 start "caw cawing" then
>it is a "guesstimate" but undoubtedly, you know the bird from it's call, it
>is a valid identification. How often do you hear the call of a solitary
>Spotted Towhee, I hear more than I see, I count them. You hear many
>Starlings in a flock, you take a guesstimate on the decibels of the bird,
>after all, if you get a visual on a large flock, this is a guess too, the
>old theory of counting groups of 10 and multiplying is never accurate, but
>obviously it is more accurate than hearing.
>
>Counting a bird by ear is valid, anyway, is this for your records or a
>birding group?
>
>
>
>Regards
>
>
>
>Martyn
>
>
>
>Martyn Stewart
>
>Birds Sounds Digitally Recorded at:
>
>http://www.naturesound.org
>
>N47.65543 W121.98428
>
>Redmond. Washington. USA
>
>Make every Garden a wildlife Habitat!
>
>
>
>The Spring is cum
>The grass is riz
>I wonder where the birdies is?
>
>The birdies on the wing!
>Nah, that's absoid
>D' wing is on d' boid!
>............................................................................
>........
>
> _____
>
>From: TWEETERS-owner at u.washington.edu
>[mailto:TWEETERS-owner at u.washington.edu] On Behalf Of Nancy
>Sent: Monday, April 05, 2004 7:03 AM
>To: Tweets
>Subject: birding counting questions
>
>
>
>Tweeters-
>
>I have a question about protocol. If you hear a bird and positively
>identify the call but do not actually see the bird, does it count as a bird
>count? (I suppose blind people do bird watch by the sound alone, but then
>they would not know exactly how many birds there were.)
>
>
>
>I am puzzled as to how anyone can count a group of 100 birds or more if
>they
>are moving? What are the techniques for counting large groups of birds?
>
>Nancy
>
>Renton, WA.
>

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