270 
M ICROPODI IFORMES 
into an even bow (Figure 388e). The swallow glides up and down invisible 
serial waves like a sailboat, the swift bores through them like a torpedo. 
The wing action of swifts has a peculiarity all its own and so rapid is the 
wing movement that it can hardly be analysed by the eye. Many who 
have studied the flight intensively have declared that the wings beat 
alternately instead of in unison. However, some recent slow motion 
pictures of the flying birds have demonstrated that this unconformity of 
wing action is an optical illusion and that, whatever other differences 
there may be, swifts fly in this particular like other birds. The shape and 
formation of the wing may give peculiar character to the flight of swifts. 
The flying surface is largely composed of the primaries, the secondaries 
give comparatively little of the supporting area. It is thus evident that 
the birds fly mostly with the wing tips which probably necessitates special 
technique and different action from that of most birds. The swifts are 
noted for the extraordinary development of the salivary glands that pro- 
duce an abundant secretion with which the nest of sticks is cemented 
together and to its perpendicular support. It is the cement thus formed 
that comprises the edible bird’s nests of Chinese epicures. 
Swifts live entirely on insects caught on the wing. North American 
swifts are divided into two subfamilies. 
Subfamily— Chaeturinae, Spine-tailed Swifts 
Not all of this subfamily have spine-tails (Figure 388c). Amongst 
the species herein treated, the Black and the White-throated Swifts are 
without them. The tarsi and toes are never feathered, but are not as 
fleshy (Figure 388b) as they are in the next subfamily. Canadian species 
except one are solidly coloured. 
422. Black Swift, black cloud swift, le martinet noir. Nephoeceles niger. 
L, 6-75. The largest of our swifts. Very dark sooty, almost black, but faintly lightening 
about head and breast, and with greyish feather edges on forehead and crown. Below, 
the female may or may not be marked with white feather tips. 
Distinctions. Large size (wing over 6 inches), black coloration, and tail not spine- 
tipped (Compare Figure 388c). 
Field Marks. The peculiar, regular bow of the forward wing outline (Figure 38Se), 
rapid, even, and continuous wing beat alternating with long, sweeping sails, general tor- 
pedo-like body outline, and dense, dark coloration will distinguish this as a swift. Its large 
size, only, will suggest its species. 
Nesting. In inaccessible clefts and crannies in the face of high mountain cliffs. 
Distribution. Western North America and the Indies, to South America. In Canada, 
only in the mountainous regions of British Columbia and adjoining Alberta, north at least 
to southern Alaska and Jasper Park. 
SUBSPECIES. The type of the species inhabits the West Indies, the bird of con- 
tinental North America is the Northern Black Swift (le Martinet noir du Nord) Nephoe- 
cetes niger borealis. 
In the neighbourhood of the beetling mountains, at irregular intervals, 
one may see, high over head, mere specks in the vault, innumerable black 
forms darting about in intricate interweaving pattern. They work up the 
valley or down. For some minutes they may be in sight and then vanish 
for hours or days. Occasionally, in cloudy weather, they may come down 
low and then the details of the Black Swift can be made out. A mystery 
surrounds them and their comings and goings. Most swifts can be traced 
with ease to their nests in the inaccessible, narrow clefts high up on the 
cliff face, but, though the Black Swift is common in many localities and 
must certainly nest nearby in numbers, it guards its secret well, and few 
nests have ever been found, or their sites located with certainty. 
