PENSILE AND CONCEALED NESTS. 179 
the larks upon it : but the construction of all these nests 
is upon the same general principle, however different 
may be the materials employed, or the degree of its 
elevation. 
( 1 55.) Pensile nests are altogether peculiar to perch- 
ing birds. They show many variations both of form 
and construction ; but all these are very diflPerent from 
those of the ordinary shape, both in the plan upon 
which they are fabricated, and the mode by which they 
are secured. The first indication of this fabric is seen 
in the nest of our common w’ren, one of which was 
erected this spring among the creepers trained round 
our portico. Its shape is irregularly oval, and is so 
disproportionate to the size of the bird, that its great- 
est length measured near twelve inches ; extern^ly, it 
seemed like a large bunch of withered leaves that had 
accidentally got entangled among the slender and sinu- 
bus stems of the clematis, and the thicker branches of 
a sweet-brier. Upon looking at it more attentively, 
however, a round opening appeared on the side, just 
large enough to admit the entrance of its little architect. 
Now a nest of this description has not a regular base, 
and yet it cannot be termed pensile or suspended ; it 
is evidently between the two, being as much supported 
by the twigs above and on its sides, as by those upon 
which it would seem to rest : perhaps we might call this 
form a roofed nest, inasmuch as by the entrance being 
lateral, its inhabitants are completely screened from the 
Weather, and from external observation. 
( 1 56.) The change of nidification from ordinary nests 
which are exposed, to thosewhichare concealed or covered, 
is marked by a beautiful gradation ; for those of some of 
the tomtits are open above, and yet they are covered. 
This union of styles is effected by the nest being fabri- 
cated in a natural hole ; by which it is, as it were, 
roofed in, without any additional labour of the bird. 
The blue titmouse (^Parus ccernleus') has for several years 
built its nest within a crevice of an outside wall, caused 
by the giving way and bulging out of the stucco ; the 
N 2 
