[TN-Bird] some thoughts on horned grebe groups

  • From: Stephen Stedman <SStedman@xxxxxxxxxx>
  • To: tn-bird@xxxxxxxxxxxxx
  • Date: Wed, 24 Oct 2007 12:43:29 -0500

I visited the Floating Mill Recreation Area on Center Hill Lake, DeKalb
Co., this morning, suspecting that some waterbirds might have made an
appearance there in the wake of the disturbed weather we've been
experiencing.  After scanning the large embayment of the lake at that
site, I found 50 American Coots in a little wad, 2 Pied-billed Grebes, 2
Gadwalls, 8 Lesser Scaups, and 9 Horned Grebes, the first of the latter
two species I have recorded this autumn.
 
The grebes were scattered over the lake in three groups of two and one
group of three.  In most years in the past when I have first encountered
Horned Grebes at this site, they have usually been scattered out in very
small groups, with groups of two predominating (if memory serves me
correctly).  Later in the fall, there will be many more grebes present,
usually in one large group for most of the day.
 
I'm wondering if there is a statistical way to analyze the early-season
groups into which the grebes fall, to see if groups of two are present
in greater number than would be expected if they occurred purely by
chance.  Would be glad of some help on this, if anyone out there is
statistically minded and interested in this matter, which might shed
light on the issue of whether pairs of Horned Grebes migrate and
overwinter together.
 
Steve Stedman
Cookeville, TN
 
And, BTW, thanks to all who responded to my query about the PIF
population estimate for Loggerhead Shrikes in TN; the consensus of the
responses, at least those that stayed on point, seemed to me to be that
the PIF estimate for LOSHs in TN was too high, even preposterously too
high, a consensus with which I am in complete agreement. sjs
 
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