ee 
390 Immature Plumage of the North American Shrikes. [Apri 
the subject, that “a full essay by some competent ornithologistis 
much needed.” Neither did the color variations of the shrikes 
escape the patient search of this rigid investigator, but I am 
not aware that our own group has ever been studied to show 
their descent from a common progenitor. In this imperfect at- 
tempt I will select the marks of coloration of but one portion of 
the body; namely, the transverse wavy lines or bars and other 
masses of color on the under surface of the body. It is well 
known that spots and stripes are more apt to fade away or change 
than larger masses of coloration in the sexual variations of ani- 
mals. All the facts here presented are taken from that excellent 
work, “A History of North American Birds, by Baird, Brewer 
and Ridgway.” 
Collurio borealis“ Breast and belly always with ` distinct 
transverse waved lines of dusky.” “In an immature bird, in 
winter, the dull white beneath is everywhere—sometimes even on 
the lower tail-coverts—covered with numerous bars of dusky, more 
sharply-defined, and darker than in the adult.” Here we have, as 
far as this one character is concerned, the male, female and young 
jsn, each other—“ beneath with wavy bars of dusky in all 
stages.” 
C. ludovicianus—This species carries us a step in advance: 
“Under parts often with very obscure faint waved lines (in the 
female?). Beneath, very strongly tinged with plumbaccous, later- 
ally and across breast.” The variation here has been transmitted 
through the female to the male, and in a modifed degree to 
female offspring. Our authors still further tell us that “ the young : 
bird is quite different from the adult, differing as does that of exci 
bitoroides, but the colors are all darker than in the oon 
age of that species.” Referring to C. ludovicianus vat. excubitorom> 
we are told that the young bird is marked on the “ breast 
sides with obsolete bars of dusky.” In the case of sik 
therefore, we have the young and female resembling each fd : 
but differing from the adult male, and resembling, in 4 modi . 
manner, both sexes and young of borealis. i 
C. ludovicianus var. ex-ubitoroides,—“ Beneath entirely W ie 
without ashy tinge laterally or across breast.” “ No we ae 
beneath.” We have already seen that the young of this bi 
obsolete bars of dusky on the breast and sides. It wer BS 
both the male and female, and resembles the adult female ot 
