8 
BULLETIN OF THE NUTT ALL 
' ON GEOGRAPHICAL VARIATION IN TURDUS ’ 
MIGRATORIUS. 
BY ROBERT RIDGWAY. 
Certain differences between Eastern specimens of the common 
Robin and those from the Rocky Mountains were first pointed out 
by Professor Baird, in his “Review of American Birds” (1864, 
pp. 28, 29), in the following words : “ In highly plumaged speci- 
mens from the East the feathers of the interscapular region are 
frequently, even generally, tinged - with blackish in their centres, 
passing gradually into ash on the edges, and the black of the head 
C€as3s to be abruptly defined. There is also usually a well-defined 
whitish tip, half an inch long, to the outer tail-feathers. In Rocky 
Mountain skins the tail is either black, except a very narrow 
whitish edge, or the white tips of Eastern specimens are replaced 
by a dull gray. The black of the head, too, is better defined, the 
interscapular feathers more uniformly ash, and the upper parts 
without the faint brownish wash so frequently seen in Eastern 
specimens. There are, however, some exceptions to these features 
in specimens from each locality. The colors generally of Western 
birds appear to be paler.” Again, in the “History of North 
American Birds” (Yol. I, p. 25), the same and additional differen- 
ces are alluded to, as follows : “ There are some variations, both 
of color and proportions, between Eastern and Western speci- 
mens of the Robin. In the latter there is a tendency to a 
longer tail, though the difference is not marked ; and, as a rule, 
they slightly exceed Eastern specimens in size. The broad white 
tip to the lateral tail-feather — so conspicuous a mark of Eastern 
birds — is scarcely to be found at all in any Western ones; and in 
the latter the black of the head is very sharply defined against the 
lighter, clearer ash of the back, there hardly ever being a tendency 
in it to continue backward in the form of central spots to the 
feathers, as is almost constantly seen in Eastern examples ; of 
Western specimens, the rufous, too, is appreciably lighter than in 
Eastern.” 
Very extensive material received at the National Museum since 
the above was written tends to confirm the constancy of most of 
these differences between Eastern and Western Robins, while other 
