214 
FRANCIS H. HERRICK 
approach, the notes becoming louder and louder as the old bird 
neared the nest. When within a rod or but a few yards from their 
young, these birds frequently come and depart in silence if their 
behavior is free, but whenever fear enters as a disturbing factor 
every approach is slow and cautious in the extreme, the bird 
stealthily flitting from bush to bush with food in bill, flipping the 
wings, and pumping head and tail in their characteristic manner 
making long pauses at one place, and sometimes encircling the 
nest more than once before actually entering it. Again when 
no disturbing influences seem to be at work, a very low and pe- 
culiar mewing sound, like kar-r-r-r-, is heard close by the nest, 
and this acts both as a stimulus to the young, and as an admonition 
to the adult, for the young respond eagerly, especially when this 
is repeated at the nest itself. If uttered by the approaching male, 
when the female broods, it is so well understood, that although 
unable to see her mate, she promptly leaves the nest, takes the 
insect which he bears, and returning quickly feeds young, inspects, 
and settles down to brood again, or if the nest is cleaned, leaves, 
and later returns with food. If the timid male approaches but 
fails to give the admonitory note, the female soon perceives him 
utters a somewhat similar low crooning note, like wur-oo-oo, and 
acts promptly as before. Still again, when the nest is reached, 
and the young are quiescent or respond but feebly, this peculiar 
note is given, and serving as a 'tickler' or 'teaser', never fails 
to arouse the nestlings to the highest pitch of excitement of which 
they are capable. 
The final approach to the nest is made quickly, and along a 
definite path, which has been determined by habit or association, 
as I have shown to be quite generally the case with birds, whenever 
their behavior is not distracted by fear. They go to a certain 
tree or bush, to a certian branch, grasp certain twigs, and finally 
enter the nest on a certain side, or in a certain manner. 
The nestlings, if not previously aroused by the sound or sight 
of their parent, or by the vibration to which the nest is subject, 
are stimulated by the final appeal just described, and the 'pot- 
boils', that is, each one rising on its pillar-like abdomen, or later 
on its toes, with upstretched and trembling neck and vibrating 
