MATING, 65 
permanent residents of the tropics, where seasonal changes 
are less marked, could nest at any time. Nevertheless, 
the breeding season in the tropics is as well defined as it 
is in more northern regions, and occurs with the return 
of summer, or the season of rains. It is therefore at a 
time of the year when food is most abundant. 
There is an obvious necessity for this regularity. Old 
birds can wander over large areas in search of food, but 
the young of many species must be fed in the nest, and 
their food supply should be both exhaustless and con- 
venient of access. 
Among our birds, the Hawks and Owls, whose young 
are fed on animal food, are the first birds to nest, while 
those which feed their young on fruit or insects wait 
until later in the year. 
Mating.—Birds are ardent lovers. In their effort to 
win a bride the males display their charms of song and 
plumage to the utmost, and will even enter the lists to 
do battle for the possession of a mate. 
It is not possible to describe here the many pecul- 
iar customs of birds during the season of courtship. 
It may simply be said that every bird will then re- 
pay the closest observation. For the scientific-minded 
there is opportunity to secure evidence bearing upon 
the theory of Natural Selection; for every one there is 
endless entertainment in the human traits which birds 
exhibit. 
The Nest.—The first step in nest-building is the selec- 
tion of a site. There is almost no suitable location, from 
a hole in the ground to branches in the tree-tops, in which 
birds may not place their nests. Protection seems to be 
the chief desideratum, and this is generally secured 
through concealment. Most birds hide their nests. 
Many sea birds, however, lay their eggs on the shores 
or eliffs, with no attempt at concealment; but, as a rule, 
