240 
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. 
423. Chimney Swift, chimney swallow. Chaetura pelagica. L, 5-43. Plate 
XXXVIII B. A small Swift of even sooty-brown colour, only slightly lightening on the 
throat and breast. 
Distinctions. The even sooty-brown colour, lightening on the throat and darkening 
towards the vent, and the tail feathers ending in a sharp spine (Figure 244 c) are sufficient 
for recognition of the species in the eastern prairie provinces where it is the only Swift to 
be expected. It is very similar to the Vaux’s Swift of British Columbia, which may occa- 
sionally occur in western Alberta, but which is considerably smaller and with rump evenly 
coloured dark like the back. The wing of the Chimney Swift is 5 inches or over. 
Field Marks. The characteristic regular bow of the forward wing outline (Figure 
244 e) the rapid, even, and continuous beats alternating with long sweeping sails, general 
torpedo-like body outline, and dense, dark coloration will distinguish this as a Swift. In the 
eastern Prairie Provinces this is the only species to be expected. In western Alberta, the 
Chimney Swift in life can be distinguished from the Black and Vaux’s Swift only by size. 
It is much smaller than the first and considerably larger than the second. Identification 
by this test, however, is very uncertain. High up in the air, with nothing to fix the dist- 
ance or scale, size is difficult to estimate. 
Nesting. Originally in hollow trees or in clefts in rock cliffs. In out of the way 
places this practice is still followed, but throughout the east such situations are almost 
entirely abandoned for the flues of unused chimneys, and occasionally the gable interiors 
of buildings. 
Distribution. Eastern North America from the lower edge of the northern spruce 
forest, southward. In Canada, west regularly to Manitoba and reported as far as central 
Alberta. The Swifts of Alberta should be closely scrutinized, and carefully identified. 
This is an interesting species, swallow-like in outward appearance and 
food-hunting habits yet structurally distinct from the Swallows. It is an 
odd example of parallel development of widely separated characters induced 
by similarity of requirement. Its habits have entirely changed since the 
advent of the white man and, forsaking hollow trees, it is now practically 
dependent upon chimneys for sites in which to build its nest. The winter 
home of the Chimney Swift is unknown. The mystery, however, should 
not be exaggerated, as there are numbers of Swifts in the western hemisphere 
looking very like this one and the bird has probably been overlooked in its 
winter quarters or confused with closely allied forms. The Swift spends 
much time on the wing and seldom comes to rest except in a chimney or 
hollow tree. In the autumn, before migration, great numbers gather 
together and at evening seek the shelter of some ample chimney where 
they pass the night. They may be seen just before dusk flying about in 
complicated patterns near the chosen chimney, and as the sun sets, circling, 
until, as they throw the wings straight up over the back and drop fluttering 
into the stack, one rapidly following another, they appear to pour in like a 
miniature maelstrom. The birds cling to the perpendicular walls of the 
chimney by hundreds, in masses like lumps of soot. Occasionally one with 
insecure hold drops a few feet, loosening, as it does so, others below; there 
is a momentary flutter of wings and a small chorus of fine sharp chippings 
until they find new holdings and settle for the night. 
424. Vaux’s Swift. Chaetura vauxi. L, 4*15. A small Swift of even, sooty-brown 
colour, lightening slightly on throat, breast, and rump. Like the Chimney Swift (Plate 
XXXVIII B), but smaller. 
Distinctions. Its extremely small size (wing, 4-50 or under), faintly pale underparts, 
and the tail spines (Figure 244 c) will separate it easily from the big Black Swift, the only 
species it is likely to be confused with in British Columbia. Its possible occurrence in 
