ngs of those that have gone before us? We have not even been able
to discover or develope any definite style of building best suited for
us. We have no characteristic national style of architecture, and to
that extent are even below the birds, who have each their characteristic
form of nest, exactly adapted to their wants and habits.

_Birds do Alter and Improve their Nests when altered Conditions require
it._

The great uniformity in the architecture of each species of bird which
has been supposed to prove a nest-building instinct, we may, therefore,
fairly impute to the uniformity of the conditions under which each
species lives. Their range is often very limited, and they very seldom
permanently change their country, so as to be placed in new conditions.
When, however, new conditions do occur, they take advantage of them just
as freely and wisely as man could do. The chimney and house-swallows are
a standing proof of a change of habit since chimneys and houses were
built, and in America this change has taken place within about three
hundred years. Thread and worsted are now used in many nests instead of
wool and horsehair, and the jackdaw shows an affection for the church
steeple which can hardly be explained by instinct. In the more thickly
populated parts of the United States, the Baltimore oriole uses all
sorts of pieces of string, skeins of silk, or the gardener's bass, to
weave into its fine pensile nest, instead of the single hairs and
vegetable fibres it has painfully to seek in wilder regions; and Wilson,
a most careful observer, believes that it improves in nest-building by
practice--the older birds making the best nests. The purple martin takes
possession 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 circumstances. 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 porous in texture than those in