v THE PHILOSOPHY OF BIRDS’ NESTS 115 
the nests were built comparatively open, so that the bird 
within was not concealed.1_ The purple martin takes posses- 
sion of empty gourds or small boxes, stuck up for its reception 
in almost every village and farm in America; and several 
of the American wrens will also build in cigar boxes, with a 
small hole cut in them, if placed in a suitable situation. The 
orchard oriole of the United States offers us an excellent 
example of a bird which modifies its nest according to circum- 
stances. When built among firm and stiff branches the nest 
is very shallow, but if, as is often the case, it is suspended 
from the slender twigs of the weeping willow, it is made 
much deeper, so that when swayed about violently by the 
wind the young may not tumble out. It has been observed 
also that the nests built in the warm Southern States are 
much slighter and more open in texture than those in the 
colder regions of the north. Our own house-sparrow equally 
well adapts himself to circumstances. When he builds in 
trees, as. he, no doubt, always did originally, he constructs a 
well-made domed nest, perfectly fitted to protect his young 
ones ; but when he can find a convenient hole in a building or 
among thatch, or in any well-sheltered place, he takes much 
less trouble, and forms a very loosely-built nest. 
Professor Jeitteles of Vienna has described various forms of 
nests of Hirundo urbica adapted to different situations, some 
having the form of a semi-ellipsoid placed vertically, with the 
entrance at one side, others being three-quarters of a sphere, 
with the entrance in the centre. A nest of Hirundo rustica 
was also observed supported on an iron hook in a wall, but 
not itself touching the wall. It was quite hemispherical, like 
that of a blackbird, a form common in England, whereas the 
usual form on the Continent is that of a quarter of a 
sphere.? 
The following case of a recent change of habit in nest- 
building was communicated to me by Mr. Henry Reeks in 
1870: “Thirty years ago, and perhaps less, the herring-gulls 
used to breed on some inland rocks in a large lake called 
1 Popular Science Monthly, vol. vi. p. 481. Quoted by Vice-President 
E. S. Morse, in Address to American Association for Advancement of Science 
at Buffalo, N.Y., August 1876. 
2 Ornithologischer Verein in Wien. Mitthelungen des Ausschusses, No. 3, 
12 Juli 1876. See also Seebohm’s British Birds, vol. ii. p. 174. 
