112 THE STORY OF THE BIRDS. 
Another plausible theory is that the male wren 
builds and pretends to defend these sham nests to 
divert the attention of an enemy from the real nest 
and his sitting mate. There is no reason why the 
bird should not be capable of such deception. But 
the nearness to each other of the nests of the tule 
wren is somewhat against this view. 
It may be, however, that these extra nests once 
had some such purpose, and they are still built by 
force of inherited habit. One other bird at least has 
a nest with a vestibule for the male to sleep in, and 
various birds resort to deception about their nests. 
Or it may be that this extra building is the result of 
the great surplus energy of these birds, just as great 
abundance of their song may be. 
Ofttimes the male alone fills the cavity with twigs 
and the female comes, burrows into the center of the 
mass, and lines it with straws and feathers. A male 
house wren was once observed to pile such a mass 
under a back porch while his. mate was on the first 
nest. So far as known she came to inspect it only 
once, and then evidently rejected it. Some of these 
sham nests may be attempts of the male to please his 
wife, and their rejection may be just the usual femi- 
nine fastidiousness about housekeeping affairs. 
Something similar has been noted in the nesting 
of the purple gallinule, an aquatic bird. 
Birds have been rather naturally but unscientifi- 
cally classified in their nest building according to the 
manner of making the nest, as carpenters (hole diggers 
in wood), plasterers (much mud in nest), weavers, felt- 
