46 'Journal of Comparative Neurology and Psychology. 



heard after the coo of the common pigeon, after the crow of the 

 domestic cock, after the cry of the whij^poor-will (Antrostomus voci- 

 ferus), and sometimes at the close of the song of the meadow-lark 

 (Sturnella magna and S. neglecta). The guttural sounds following 

 the coo of the ring-dove are usually a distinct enunciation of the sylla- 

 bles "go 0." These gutturals, however, show extreme individual 

 differences in quality, intensity and duration, in some cases the two 

 syllables being reduced even to a single sound. This extreme indi- 

 \idiial difference, conforming to no law or system, is one of the facts 

 which indicate that the gutturals merely have to do with regulating 

 the breath, and should be regarded as involuntary after-effects of 

 the coo proper. 



The coo of the female is always less powerful than that of the 

 male. !Not only is the intensity less and the pitch in many cases 

 lower, but the notes are much shorter, thus destroying the richness 

 of the strain. Often, too, the inflection is lacking, or is hurried and 

 slurred in such a manner as to produce a travesty of the coo of the 

 male. If a female be kept long in isolation, with no chance to satisfy 

 her sexual and social desires, she becomes so self-assertive, bold, and 

 boisterous, that she is scarcely to be distinguished from a male, either 

 by her cooing or by any other form of behavior (cf. p. 43). But 

 when a female is quietly pursuing the normal activities of the 

 breeding-season, her voice is so different from that of the male that 

 her coo alone is usually sufficient to determine beyond a doubt the 

 fact of her sex. 



Aside from these variations in the case of the female, the coo is, 

 as has already been mentioned (p. 15), a pretty constant sound, much 

 less variable than the kah. In different individuals the coo is 

 slightly different in pitch, inflection, and duration. But the melody, 

 in its main outlines, and the syllabication are, so far as I know, 

 invariable. 



The general description just given applies to all the coos of this 

 species, but these coos are divisible into three types which are kept 

 perfectly distinct, there being no gradations between them. The 

 chief means of distinguishing these three types of coo is the difference 

 between the bodily attitudes and movements accompanying each. 



