Hi Gene, Marcia, et al.
A good line of questioning ...
FYI. Below is the "Systematics" section from the Birds of North America
on-line account for Common Grackle. Hope this helps.
Phil
COMMON GRACKLE (Quiscalus quiscula)
GEOGRAPHIC VARIATION
Plumage coloration varies regionally. Breeders west of Appalachians and
north of s. New England have brassy bronze body and purple glossed tail,
whereas birds east and south of there have purplish body with green to
steely blue glossed tail. Birds of extreme southeast (Florida) have green
backs. Wide zone of intergradation stretching from s. New England to
Louisiana where intermediates occur. Wing length and body mass decrease
north to south, whereas bill length and width increase along that cline
(Huntington 1952, Yang and Selander 1968).
SUBSPECIES
Three subspecies recognized (Am. Ornithol. Union 1957, Blake 1968). The
basic outline of morphological characters and geographical distribution of
these forms was a source of confusion for many years and mostly worked out
by Chapman (e.g., 1892, 1936). Apart from subtle change in bill and wing
size outlined above, the chief characters separating the subspecies are the
color of the back, tail, belly, and to lesser extent, head.
Q. q. versicolor Vieillot, 1819. Often called the Bronzed Grackle, this
race breeds over most of the range of the species north and west of a line
running from central Louisiana to s. New England along western margin of
the Appalachians. This race is highly migratory, wintering south to s.
Texas and east to South Carolina, thus overlapping with the next 2
subspecies; versicolor also accounts for all records of vagrant Common
Grackles to the west of the Rocky Mtns. This race is less variable in
coloration than the next and typically shows a uniformly brassy bronze back
and belly and purplish tail. The head color is somewhat variable but
usually blue-green. This race was formerly considered a separate species.
Q. q. quiscula (Linnaeus, 1758). Known as the Florida Grackle, this race is
essentially resident from se. Louisiana east to se. North Carolina and
south to s. Florida. The back is typically dark green and the tail
blue-green; the head is usually purple and the belly purple-blue.
Q. q. stonei Chapman, 1935. Often referred to as the Purple Grackle, the
distribution of this race is not well-defined but generally given as lying
between the above 2 races east of the Appalachians from se. New York
(formerly to sw. Connecticut?) south to central Alabama and west to central
Louisiana. Back and belly typically purple; tail usually blue-green.
Formerly considered a subspecies of the Florida Grackle when that and the
Bronzed Grackle were considered separate species. Along the area of contact
between versicolor and stonei from Louisiana to Connecticut, a narrow band
of intermediate forms have been designated Q. q. ridgwayi by Chapman. These
"Ridgway's Grackles" show a strong barred effect on back. These
intermediates and the status of stonei as a valid subspecies are questioned
by Huntington (1952).
CITATION:
Peer, B. D., and E. K. Bollinger. 1997. Common Grackle (Quiscalus
quiscula). In The Birds of North America, No. 271 (A. Poole and F. Gill,
eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American
Ornithologists' Union, Washington, D.C.
At 23:58 12/29/2005, Gene Scarpulla wrote:
>On Tuesday, December 27, 2005, Marcia Watson-Whitmyre and I observed four
>Bronzed Grackles at her feeders most of the day. This raised a few
>questions in my mind about the prevalence of Purple versus the
>northern-migrant Bronzed Grackles that winter in Maryland.
>
>1) Those of you with backyard feeders, which races of grackles do you observe?
>
>2) Those of you that observe large grackle flocks, which races of grackles
>do you observe and in what ratios?
>
>3) Is the occurrence of Bronzed Grackles more prevalent in specific
>regions of the state?
==================================
Phil Davis Davidsonville, Maryland USA
mailto:[log in to unmask]
================================== |