Vv THE PHILOSOPHY OF BIRDS’ NESTS 107 
and it seems highly probable that the older birds would begin 
building first, and that those born the preceding summer would 
follow their example, learning from them how the foundations 
of the nest are laid and the material put together.1 
Again, we have no right to assume that young birds gene- 
rally 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, Dr. 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 
1 It has been very pertinently remarked by a friend that, if young 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 sur- 
rounded 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 para- 
graphs, but the question can only be finally decided by a careful set of 
experiments. 
