298 
PASSERIFORMES 
variation is considerable. In migration many wander far from their 
breeding homes and mix together, and, in some cases, late migrants do not 
leave southern stations before resident birds are rearing young. In the 
mountains, forms may be separated by no more than altitude and but a 
few miles of territory. All of these factors tend to make rules on identifica- 
tion and ranges of the forms of this species a difficult matter, and may 
require constant revision of opinion until much more work has been done 
and more complete series of specimens are available for examination and 
comparison. 
The Horned Lark is a bird of the open, frequenting bare fields, beaches, 
or roadways. In the winter, the seeds of weeds projecting from the snow 
are its main food supply, and numbers frequent travelled roads for the 
partly digested grain dropped by the horses. Occasionally large winter 
flocks appear. It is in such migrant congregations that the rarer forms 
should be looked for. 
FAMILY HIRUNDINIDAE. SWALLOWS 
General Description. Mostly small birds, in Canada only one, the Purple Martin, is 
as large as a House Sparrow. Wings very long and pointed; feet small and weak, unsuited 
to walking; head flattened and bill very short, with deep, wide gape (Figure 400a and a 1 ). 
Distinctions. In superficial characters and general proportions as here described, 
swallows resemble the goatsuckers and swifts, but are much smaller and entirely different 
in colour from the former and are not nocturnal. In the field, more likely to be confused 
with the swifts. The wings, with their looser and softer feathers, the nearly straight 
primaries, longer secondaries (Figure 400d and e), and the characteristic wing action 
are sufficient to show the great difference in the birds. The swift beats the air with rapid, 
regular strokes and then sails like a bullet; the swallow flies with long, rhythmic strokes, 
gliding up and down invisible aerial waves, instead of boring straight through them. 
The legs and feet of the swallow are more or less scaly, and not as fleshy as the swifts 
(Compare Figure 400 with 388, page 271). 
A world-wide family, of aerial habits, seldom coming to the ground 
except for nesting material. Their feet are weak and suitable for alighting 
only on small twigs, telegraph wires, and similar perches. They take their 
Figure 400 
Characteristic details of Swallows. 
head of Cliff Swallow. o 1 , top view of bill, b, foot, d, wing tips, e, outline of Cliff Swallow in flight. 
Scale: a-d, natural size; e, about i. 
