CUCKOO PUZZLES ‘41 
birds which we have seen elsewhere, which is often 
attributed to their mistaking the cuckoo for a hawk? 
There remains something puzzling here. 
Wordsworth called the cuckoo a “mystery,” 
-and its behavior certainly presents many puzzles. 
The central one is the mother’s evasion of brooding. 
As is well known, she usually lays her egg on the 
ground, takes it in her beak (sometimes under her 
tongue), and flies with it to the previously-selected 
nest of another bird. Sometimes when the nest 
is suitable she lays her egg directly in it, but this 
is often impossible. All is done quickly, cautiously, 
surreptitiously. There is considerable evidence that 
each cuckoo keeps as a rule to one kind of nest, 
and although over a hundred different kinds of 
foster-parents are on record, the list of favorites 
is not very long. It includes Hedge-Sparrow, Pied 
Wagtail, Titlark, Tree Pipit, Robin, Reed Wren, 
Warblers, Shrikes, and so forth. Unless some big 
mistake is made the foster-parents incubate the 
intruded egg, and rear the young cuckoo, who 
sees to it that they are not distracted by any rival 
claimants. The parent cuckoos are not known to 
take any interest in their progeny, and they leave 
our shores for the South a month or six weeks be- 
fore the young birds are able to travel. The “ para- 
sitism ” works well, and in the Common Cuckoo 
there is no exception to it. What light can be shed 
on the puzzle? 
There are three considerations that make the 
evasion of brooding less perplexing than it appears 
