THE ROLE OF SEX STEROID IN 2 AVIAN SONG BEHAVIORS DIFFERING IN ONTOGENIC PROCESS

The male Bengalese finch, Lonchura striata, has two types of song beha viour (directed song, DS and undirected song, US). DS and US share a b asically identical syllable repertoire, sequence pattern and tempo, bu t differ in the time course of appearance during the maturational proc ess. In order to examine whether this results from a difference in tes tosterone (T) dependency, we studied developmental changes in the feca l T level and the amounts of DS and US during the 2-4 month period (N = 7). DS appeared between 83 and 94 days of age, 4-16 days after a ris e in the fecal T level. In contrast, US appeared earlier and at high f requency even when T was still at a very low level. These results sugg est that DS is more dependent on the T level than US, and is not activ ated until the T level rises during the maturational process.