Abstract: This paper reported the singing ecology and behavior of concolor gibbon in Yunnan, P. R. China based on the field studies o f a yearly monitered group GS in 1995 and some other groups such as GA, GC and GG monitered and studied from Ma r. 1990 to Jan. 1992. Mated gibbons usually sing duets in morning , and mo st o f them occurs before 0930 hr. The start time of duet, however, shows that there are two peaks ( around 0730 hr occurred from July to Oct. and 0830 hr from Nov. to June) annually , and also show s no consensus with the dawn time. Generally, concolor gibbons sing once every two days, the average daily singing occurrence of GS is 47. 5% and that o f GA is 54. 3% , and the occurrence changes with seasons, e. g. , it drops to 10% in GS in May and rises up to 80% in GA in Sept. The duration show s no significant difference between groups ( P> 0. 10) , the media n length of duets is about 12 min. , but there is a monthly difference in group. An exception is GG, which sing s an average of 19. 6 min. ( SD= 4. 2, n= 16) , much longer than all other groups. And this paper does no t verify the result that singing of a group would trigger singing of other groups.

Key words: Hylobates concolor, Singing, Evcology and behavior