SWALLOWS. 333 
agency, and more or less fully furnished with soft material, according to the shallowness 
or depth of the retreat. (Formerly, no species; now, all the species excepting Cotyle 
riparia.) 
‘“‘4, Holes constructed by the birds, of mud, plastered to surfaces, whether artificial 
or natural, and loosely furnished with soft material. This is seen in perfection in the 
nesting of Petrochelidon Iunifrons, and is imperfectly illustrated by the nidification of 
Chelidon erythrogaster. It has every appearance of an acquired trick, by which these 
hole breeders carry out their original instincts on a greatly improved plan..... 
“Connected both with the migration and nidification of Swallows are some remark- 
able facts relating to the return of the same pair of birds to the same nest year after 
year. In the nature of the case, this is difficult to determine with certainty; but 
observations which have not seldom been made on birds that were marked by some 
recognizable peculiarity have established the fact beyond question. Far from being 
singular, however, it accords with many observations made upon birds of other families. 
How marvelous, how admirable, how complex and subtile, must be the mental faculties 
of such humble creatures, who can find their homes again with unerring precision, after 
On the general habits and traits of Swallows our author writes as follows: 
“... The most graceful flyers among the Swallows are the lashing-tailed species 
of Chelidon proper, like the Barn Swallow, which glides, soars, and sweeps with 
extraordinary facility, and instantaneously arrests or diverts its flight at a touch 
of the guiding helm. The motion of the Swallow skimming the ground, and ‘quartering’ 
in zigzag after its prey, has been aptly compared to the coursing of the greyhound. 
No one who has attentively observed the flight of Swallows can have failed to notice 
their peculiar ‘towering,’ when they rise abruptly with few vigorous strokes, and seem 
to hang suspended for a moment, before falling with great velocity through the 
beautiful curve of the cycloid—with half gathered wings, and at such little loss of 
impetus by friction that they avail themselves of this peculiar line to rise nearly to 
their former level without muscular effort. Sometimes their course is as straight as an 
arrow’s, and only less swift—sometimes they hover and flutter at seeming random, and 
not the least marvelous of their. feats is the spirited dash they make, with unerring 
aim, to enter the narrow window or belfry, and settle, as light as a feather, with 
joyous twittering, on the nest. 
“The feeding of Swallows is almost an inference from the structure of the bill, 
wings, and feet. These delicate birds have very weak bills, but very capacious mouths, 
and seem not very dainty in their choice of food. They would soon be starved if forced 
to gather food on foot—on the wing, no one of the smaller flying insects is safe from 
that gaping bill, split to the very eyes, propelled with enormous velocity into their 
ranks, and capable of following after, to close on the most agile and devious bug. 
Swallows feed on the wing, and this prime point in the economy of these indefatigable 
insect hunters is signalized in the very names the birds have acquired in various lan- 
guages. Not only the mode of flight, but its direction, whether high or low, and the 
entire migrations of the birds, turn upon the prime point of food supply; and upon 
this hinges, secondarily, the recognized relation between the movements of Swallows 
