FreeLists / tn-bird / [TN-Bird] Re: more on those cumberland county henslow's sparrows; and some bbs ruminations

[Bill Pulliam <bb551@xxxxxxxxxxxxx>]

Speaking as someone who just this summer turned up one of those  
small, previously undocumented populations, my experience may be  
relevent to the quest for better information:

I did not just happen to stumble across the birds.  I read on TN- 
birds and on the Henslow's Sparrow Atlas project page about the known  
distribution and the detailed habitat requirements, and I thought  
long and hard about where there might be patches of this habitat in  
Lewis County.  Once I came up with what seemed to be the best bet  
(The Farm's large unmowed fields), it fortuitously happened that I  
was going to be going there in a few days to help Cynthia Rohrbach  
with point counts.  I made a point of being especially alert for that  
easily-overlooked song when we walked along the best habitat, and  
sure enough, we found one.  Later visits by other observers found at  
least three.

I think this semi-systematic approach is the best bet:
(1) learn the habitat
(2) study maps, drive backroads, search your recollections to find  
this habitat in the area
(3) go there and listen listen listen.

The recently-known distribution suggests there could be be Henslow's  
Sparrows in any suitable field ANYWHERE in Middle Tennessee, as there  
are records this summer alone from the West Highland Rim, East  
Highland Rim, Central Basin, and Cumberland Plateau.  Some of the  
West Highland Rim counties are pretty short on barrens habitat  
(Perry, Hickman, Wayne come to mind) but who's to say they aren't  
also going to be found in fields in the larger bottomlands on the  
Duck, Buffalo, etc.?  And no rason to  rule out East and West  
Tennessee.   Many recent records are outside the "historical range;"  
regardless of whether this is from range expansion or better observer  
knowledge, it means that we should be alert to the possibility from  
border to border, not just near places they have already been found.

The BBS/Henslow's Sparrow issue is a general problem with BBS and  
other point-count-based surveys.  They do not adequately sample birds  
with clumpy distributions.  We often think of herons and such in this  
regard, but it also includes birds like Henslow's Sparrow, Willow  
Flycatcher, and Dickcissel in the areas where they are less common.   
At The Farm, the Henslow's Sparrow colony (if three birds do a colony  
make) fell between point counts on the transect; had we been driving  
instead of walking between the points we would have missed them.   
These sorts of birds are best found by targeted searches of clumps of  
suitable habitat.  Unfortunately, this isn't generally going to  
happen until we are first alerted to their possible presence by a few  
chance encounters, so these birds can remain unnoticed for decades.   
Back when I was working the South Carolina Breeding Bird Atlas, one  
of the many surprises was the widespread presence of "Piedmont"  
warblers (Ovenbird, Worm-eating, Black-and-white, etc.) in small  
bottomland hardwood patches amongst the pine flatwoods of the Lower  
Coastal Plain.  After I stumbled on a few, and began more targeted  
searching, they turned up in nearly every block I covered in that area.

Bill Pulliam
Hohenwald TN
http://bbill.blogspot.com
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