birds did observe the nest they were reared in, |
| they would consider it to be a natural production like the |
| leaves and branches and matted twigs that surrounded it, and |
| could not possibly conclude that their parents had |
| constructed the one and not the other. This may be a valid |
| objection, and, if so, we shall have to depend on the mode |
| of instruction described in the succeeding paragraphs, but |
| the question can only be finally decided by a careful set of |
| experiments. |
+--------------------------------------------------------------+

Again, we have no right to assume that young birds generally pair
together. It seems probable that in each pair there is most frequently
only one bird born the preceding summer, who would be guided, to some
extent, by its partner.

My friend, Mr. Richard Spruce, the well-known traveller and botanist,
thinks this is the case, and has kindly allowed me to publish the
following observations, which he sent me after reading my book.

_How young Birds may learn to build Nests._

"Among the Indians of Peru and Ecuador, many of whose customs are relics
of the semi-civilisation that prevailed before the Spanish conquest, it
is usual for the young men to marry old women, and the young women old
men. A young man, they say, accustomed to be tended by his mother, would
fare ill if he had only an ignorant young girl to take care of him; and
the girl herself would be better off with a man of mature years, capable
of supplying the place of a father to her.

"Something like this custom prevails among many animals. A stout old
buck can generally fight his way to the doe of his choice, and indeed of
as many does as he can manage; but a young buck 'of his first horns,'
must either content himself with celibacy, or with some dame
well-stricken in years.

"Compare the nearly parallel case of the domestic cock and of many other
birds. Then consider the consequences amongst birds that pair, if an old
cock sorts with a young hen and an old hen with a young cock, as I think
is certainly the case with blackbirds and others that are known to fight
for the youngest and handsomest females. One of each pair being already
an 'old bird,' will be competent to instruct its younger partner (not
only in the futility of 'chaff,' but) in the selection of a site for a
nest and how to build it; then, how eg