Mae td Mousey, Subsequent Nestings. 393 
but for just how long that season lasts or the reproductive faculties 
of the birds remain active I am unable to say. Perhaps doctors 
from their special training may be able to throw some further 
light on the subject, in the meantime I have formed an opinion of 
my own (perhaps erroneously) that when birds forsake the vicinity 
of the nesting site after the loss of their second or third set of eggs, 
they do so because the power or natural instinct of reproduction 
has reached its limit, and is over for that particular year. In 
support of this theory, I have constantly referred to the fact of so 
many of the birds returning the following year to the old nesting 
site, and in the case of the Kingbird, Downy Woodpecker and 
Catbird, actually occupying the same trees and bush again. Now is 
it reasonable to suppose that they would do this, if after deserting 
the site the previous year, they had found a fresh one, and brought 
up a brood? Surely they would have returned to that site with its 
pleasant associations, rather than to the one with its unpleasant 
recollections. 
In conclusion it seems to me that the more and more we go into 
these bird problems, the more is the fact brought home to us of the 
very little we really know concerning them, and at best our solu- 
tions in most cases can only be approximate ones after all. 
