Seems to me I learned from Phil DuMont when I was a beginner( 1951)  
that you can recognize the Mimic thrushes by:
          no repeats------------------ catbird
           two or three repeats-------- brown thrasher
         six or seven repeats-----------mockingbird
 
It's always worked pretty well for me with the eastern mimics.
David Pierce

Speicher, James (NIH/NIAID) wrote:

>	Kevin Caldwell wrote:
>	I'd swear to all ends that I'm hearing a great crested flycatcher
>around my home, but don't think they could be here and calling this early.
>
>	Janet Millenson wrote:
>	I had the exact same experience a few years ago. The apparent
>out-of-season flycatcher turned out to be a very talented mockingbird.
>
>	Ben Weinstein wrote:
>	I've had the exact same problem... After a half hour i did 
>	find a northern mockingbird doing a fantastic impression of both a
>Great Crested, and a brown thrasher.
>	************************************************
>	Isn't it true that mockingbirds will clue you in to their masquerade
>by the fact that they will repeat a phrase 6 or 7 times, before shifting to
>another song for 6 or 7 repeats, shift again for 6 to 7 repetitions, etc.,
>etc. and finally coming back to the "original" song?  At least that's what
>i've found to be the case.  Isn't this mentioned in the newer guides?  I
>believe I saw it is in my Robbins guide years and years ago.
>
>	Jim Speicher
>	Jspeicher-at-niaid.nih.gov
>	Rockville @work :(
>	Broad Run_S. FRED Co @home :)
>
>  
>