_Identification Guide to North American Passerines_ by Pyle, Howell, Yunick
and DeSante makes no mention of different coloration of rictal bristals for
in-hand identification.

They do, however, list the traditional features including pale base to
the lower mandible (NSHR) , connective mask (LOSH), Distinctict
Supercilium (NSHR), Extensive barring to underparts (NSHR).

NSHR=Northern Shrike
LOSH=Loggerhead Shrike


--
******************************** A round man cannot be expected to fit into a
* Mike Patterson, Astoria, OR * square hole right away. He must have time t
* mpatters at ednet1.osl.or.gov * modify his shape.
******************************** -Mark Twain