176 
FRANCIS H. HERRTCK 
occasionally laid her eggs on the bare ground, brooded them, and 
fed her young. ''This rare event," said Darwin, ''is probably 
a case of reversion to the long-lost aboriginal instinct of nidifi- 
cation." 
Nest-building must have been an ancient practice among birds 
when the cuckoo began to acquire its present habits, and the fact 
that it takes a lively interest in nests, — that so many of its present 
instincts and associations have to do with nests, points direct to 
the conclusion that it once made its own nest, or at least brooded 
its own young. 
4. Although in the pairing season^ fights occur among the 
males, the female European cuckoo is for a time at least polyan- 
drous, there being five or more males, (or suitors) according to 
conservative estimates, to every female. (Compare no. 2.) 
5. "The female cuckoo, with or without a male, and either 
before or after union, searches for nests of suitable nurses, and 
when found, watches them from the beginning of nest-building 
day by day, in order to choose the one most suitable." (Baldamus, 
and others.) Since we are convinced that the behavior of this 
bird has been molded by instinct rather than determined by free 
ideas, we should lay no stress upon choice or motive, as the writers 
quoted here or in subsequent paragraphs seem to have done. 
6. The eggs of this cuckoo are relatively very small, and have 
thick resistant shells. When taken at random, they are very vari- 
able in color, ranging from blue or blue-green, through speckled 
blue, brown, mottled or marbled brown and gray to nearly plain 
white. 
7. The same cuckoo lays only one egg in the same nest, a 
statement which has come down from antiquity, and is generally 
credited, especially by those who accept the following : 
8. The same cuckoo always lays eggs of similar color, color- 
pattern, size, and form, in a single season, and probably daring 
life. According to Baldamus this has been proved to hold true 
' Some, like Jenner, have maintained that cuckoos do not pair, and while this 
view is not supported by more recent observers, the subject is still somewhat 
-vague. There may be variation in this, as in so many other respects. 
