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M. Moynihan 
(Canal Zone Biological Area, panama Canal Zone) 
INTRODUCTION 
T he performance of certain behavior patterns, which have been called "consummatory 
acts" (see Lorenz, 1950), is usually followed by an obvious and rapid drop in respons- 
ivcnoss to the stimuli releasing the patterns, an apparent decrease of "internal 
motivation", "reaction specific energy", or "specific action potential”. The precise 
nature of this effect is still debatable (see, for instance, the discussion in 
Bastock and Blest, 1958), but it has usually been thought to be the direct and 
inevitable result of the mere performance of particular movements. Bastock, Morris, 
and Moynihan (1953) have suggested, however, that it is not the performance of a 
consummatory act alone which brings about the apparent drop in motivation, but rather 
the reception of certain "consummatory stimuli" during or after the act. 
Some vocal patterns of certain Central American passerine birds may be of 
interest in this connection; as they may be terminated by the reception of consummatory 
stimuli from the external environment without the performance of any activity which 
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might be considered a consummatory act in the conventional sense of the term. 
T 
"•These patterns have been studied in several species on Barro Colorado sland 
and the mainland of the Panama Canal Zone, and adjacent areas in the Republic of panama. 
DESCRIPTION OF AN APPARENTLY TYPICAL CASE 
The so-called "song" of the Blue Tanager ( Thraupis episcopus ) may be taken as 
an example of the type of pattern to be discussed here. 
The sound of this song has already been described by several authors (e.^« 
Eisenmann, 1952 ; Skutch, 1954). It consists of a moderately long and complex, but 
not very melodious, single phrase. 
