5 
BUTEO BOREALIS HARLANI, HARLAN^ HAWK 
This hawk is nearly as puzzling as Krider’s and from the same cause. 
It, too, was originally described from a juvenile (Plate III, figure 8) and 
the application of the name to the adult has been assumed, but not here- 
tofore demonstrated. Harlani occurs in two phases, a completely melanotic 
one and a white-breasted form very similar to the normal borealis juvenile. 
The adult is characterized by a tail freckled, marbled, or mottled with 
shades of black, white, grey, or red in various proportions (Plate I, figures 
16-22; Plate II, figures 3, 6)- — in fact no two seem ever to be exactly alike, 
but the peculiar design of pattern and the tendency to form longitudinal 
aggregations of specklings are characteristic. 
Juveniles of harlani have the same dark, black-barred tail (Plate I, 
figure 22; Plate III, figures 4, 8) that is normal to borealis and calurus 
(Plate I, figures 3, 7, 8) and which occurs more or less frequently in krideri 
(Plate I, figures 12, 14, 15). Such birds may be impossible to recognize 
as harlani by any test now known. 
This irregularly mottled or marbled tail seems to be the only constant 
criterion of adult harlani. At all ages harlani tend to be a purer black 
(less brown) than the melanos of calurus, but this is not constant and 
several specimens have been examined in which the black is distinctly 
brown. The writer has never seen one with decided reddish areas on 
breast or elsewhere except the tail (Plate I, figure 21); but suggestions of 
red breast occur in some specimens (vide, Koelz specimen, Pea Ridge, 
Arkansas, Feb. 8, 1925), and in view of the extraordinary variability of the 
species he would hesitate to say that it never occurs in stronger degree. 
Many young birds as they leave the nest have considerable ochre or 
rusty ochre feather edges on breast, underparts, flags, and elsewhere to a 
lesser degree. Most of this appears to be lost by fading and wear soon 
after leaving the nest and by the time the birds are able to fend for them- 
selves it is very largely reduced to pure white. As in other forms of the 
species, this white usually spreads from the breast, where it may show as a 
few semi-concealed streaks and it may extend until it merges the melanotic 
into the light phase (Plate III, figures 3, 6). The white of the back is also 
more or less variable. There is a general tendency toward light or white 
crossbarring on back and wing coverts that may be either concealed or 
exposed. In many of the darker birds these show only as slight, indefinite 
grey spots like pale thumb-marks over the upper surface of the body. 
Others are distinctly if unevenly white spotted, in extreme cases even 
approaching the general appearance of krideri (Plate III, figure 6). 
BUTEO BOREALIS ALASCENSIS, ALASKA RED-TAIL 
Of general calurus character (light phase), but of small size and with 
richer and darker colours. 
The writer has examined the cotypes of this form in the Museum of 
Vertebrate Zoology, but saw no new character nor any new association of 
characters in them. Two adults seem like ordinary small-sized calurus 
with red tails, one narrowly but decidedly barred, the other practically 
unbarred. One juvenile is of normal light phase, the other is partly 
melanotic. These birds have the darks blacker and richer than specimens 
from more arid regions; but this is true of many of the northwestern mem- 
