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In St. Louis area, I believe the line is essentially the Missouri  
River.  The contact zone veers southwest in the western part of the  
state.

Sometimes there isn't much difference between hearsay and heresy.   
The old definition of a species heavily relied on infertile young as  
a basis for determining separate species.  That criterion, when  
applied to Baltimore and Bullock's Orioles in their contact zone in  
the upper midwest (a zone created by the planting of trees in the  
former barrier of the plains) gave us the short-lived species,  
"Northern Oriole."  Subsequent DNA work showed that they are not even  
the closest of relatives.

The definition of species is changing.  News creeping into the  
general birding population is that recent DNA work will change our  
perception of species greatly.  Look-alikes are often not as closely  
related as they seem.  Behavior is often learned (including songs and  
feeding techniques).

As for chickadees, it will be interesting as this DNA work gets a  
full explanation.

Edge Wade
Columbia, MO
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member, ASM

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