[Effect of testosterone on the beginning of singing in the zebra finch (Taeniopygia guttata castanotis)].

In young male Zebra finches, singing was advanced in time by injections of testosterone-propionate. The juvenile song, which normally occurs on day 34 to 37, could be shifted to day 18 to 19, when injection took place at the 16th day; either earlier or later injections delayed singing (at 25 to 35 days). The advanced juvenile song differs from the normal one, mainly the rhythm is less mature. There seems to be a point prior to which juvenile song cannot be induced, depending possible on the maturation of central nervous motor centers.