David,
The counts are quite similar, which feels good. We did use the method you described - we counted the entire flock then estimated percentages within this). First I counted the swans because they're easy and they were the first ones I've seen this season. As for the rest, like you we didn't want to get too technical - we began by counting out the first 200 individually, got an eye for a block of 100, and then counted the rest in blocks of 100. We then sampled different sections of the flock. Quite a few Canvasbacks and Ring-necks arrived while we were there (9:30-10:30) so I'm sure the flock was somewhat different from what you counted.
Dave
-----Original Message-----
From: Maryland Birds & Birding [mailto:[log in to unmask]]On
Behalf Of David Mozurkewich
Sent: Friday, December 09, 2005 1:46 PM
To:
Subject: Re: [MDOSPREY] Piscataway waterfowl
Dave and George,
I, too, spent yesterday morning, December 8, at Piscataway, starting at
Wharf Road about 8AM. I'm sorry we missed -- I rarely see other
birders here. After Wharf Road, I went to the Colonial Farm, then
walked the Piscataway boardwalk ending the morning at Mockley Point.
The vast majority of the waterfowl I saw were visible from your vantage
point.
Normally, I have very little confidence in my estimates of flock size,
even when the birds are lined up, stationary and easy to count. When
they're packed into small openings in the ice, actively feeding and
moving around, the count gets a lot harder. Add to that the challenge
of dividing the count by species. I know, I'm supposed to estimate
the size of the entire flock, then come up with percentages for the
major constituents but that's easier said than done especially when
different species are concentrated in but not exclusive to different
parts of the flock. In preparation for the upcoming CBCs, I'd love to
hear how others tackle this challenge.
I considered doing a careful count of these waterfowl, but didn't. I
decided that was too much like work and I was out to have fun. What I
*did* do is count a few of the less-common species in some parts of the
flock and I was not very careful at that. I also did an even cruder
estimate of Ruddy Ducks. (I looked at the flock and said "mm, looks
like about 2000.") Then, after I was home and warm I took a wild guess
at everything else based on my recollection of their relative
abundances.
I still don't believe my counts and considering the method I used this
time, I am absolutely dumbfounded at the similarity of our results.
This is especially true since the less-common species are easy to
overlook among the multitudes and ducks have wings so there is no
guarantee we "counted" exactly the same flock. For comparison, I
repeat your report here with my numbers added in the second column
Canada Goose 300 300
Tundra Swan 161 100
Mallard 400 70
Green-winged Teal 1
Black Duck 10 10
Gadwall 100 100
Pintail 5 20
American Wigeon 2 10
Shoveler 100 50
Canvasback 300 200
Redhead 10 2
Ring-necked Duck 800 500
Lesser Scaup 10 5
Hooded Merganser 2 10
Ruddy Duck 1000 2000
Bufflehead 3
>From my other vantage points on the open Potomac, I added Greater
Scaup (15), Common Merganser (3) and Long-tailed Duck (3) bringing
the total waterfowl count up to a respectable 19 species. I also
saw one Common Loon.
Dave
--
David Mozurkewich
Seabrook, PG, MD |