241 
western Alberta makes it necessary to differentiate it from the Chimney Swift; size is the 
best distinction, but the rump and uppertail coverts are slightly lighter than the back, 
instead of being of the same colour. 
Field Marks. The characteristic regular bow of the forward wing outline (Figure 
244 e), rapid, even, and continuous beats, alternating with a long, sweeping sail, and general 
torpedo-like body outline, with dense, dark coloration, will distinguish this as a Swift. 
In the eastern Prairie Provinces this species is not to be expected. In British Columbia 
it is to be confused only with the Black Swift, which is a much larger bird; and the 
White-throated, which is very local and strongly marked with white. Near the mountains 
in Alberta it may be taken for the Chimney Swift, from which it can be separated only by 
its smaller size. Swifts in this locality should be very carefully identified. 
Nesting. In communities in hollow cottonwoods, and similar trees, occasionally in 
buildings, water tanks, etc. 
Distribution. Western North America, In Canada, interior valleys of southern 
British Columbia and on the coast as far north as southern Alaska. 
This bird is somewhat local in British Columbia and its distribution is 
largely determined by the presence of suitable hollow trees. Though 
much like the eastern Chimney Swift, it has not followed the example of 
that species in using chimneys for nesting. 
Subfamily — Micropodinae. Typical Swifts 
This subfamily is chiefly Old World in distribution and is represented 
in Canada by but one species of very rare or local occurrence. The tail 
is spineless. The feet are thick, fleshy, and more or less flattened. The 
single species here considered is easily recognized by its white throat and 
breast. 
425. White- throated Swift. Aeronautes melanoleucus. L, 6-75. Nearly as large 
as the Black Swift, but with extensive white throat, breast, and line down abdomen, tips 
of secondaries, and a patch on each side of the rump. 
Distinctions. The only Canadian Swift with decided white patches. 
Field Marks. The characteristic, regular bow of the forward wing outline, rapid, even 
and continuous wing beat, alternating with long sweeping sail and general torpedo-like body 
outline will distinguish this as a Swift. The white throat and breast, and the white spots 
on either side of the rump will identify it as this species. The Violet-green Swallow associ- 
ates with it and has similar white spots beside the rump, but the flight action is that of a 
Swallow instead of a Swift. 
Nesting. In inaccessible clefts and crannies high on the face of mountain cliffs. 
Distribution. Western North America south to Lower California. In Canada, 
known to occur only in the southern Okanagan valley of British Columbia. 
Too rare and local in Canada to be of much general interest, but no 
Canadian ornithologist can visit their haunts without enthusing over them. 
Their wonderful and spectacular speed of wing and their unattainable 
communal nesting strongholds, around which they turn and wheel and 
swoop, so high as to make it uncertain even with field-glasses whether they 
are birds high up or flies lower down, pique the bird-lover who sees them 
day by day at their most private affairs and yet never gets familiar with 
them. 
SUBORDER— TROCHILI. HUMMINGBIRDS 
These tiny birds, with brilliant flower-like coloration, insect-like 
flight, and wonderfully varied form, are a typically American order. In 
a way, they occupy much the same position in the New World as the Sun 
Birds do in the Old World, but the similarity between the two is super- 
ficial and not one of relationship. Many species are highly specialized and 
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