Vocal behaviors and spectrum characteristics of Black-necked Cranes(Grus nigricollis)

Vocal contact as a communication tool plays crucial role in the life history of birds. In this study, we studied the short vocal behaviors of Black-necked Cranes (Grus nigricollis), and characteristics of these calls were analyzed. All the sound samples were collected from wild population in the Dashanbao National Nature Reserve during November, 2009 to March 2010 and from captive individuals in the Beijing Zoo in June-July, 2010. Six short call types were recorded including of contact call, flight intention call, alarm call, guard call, assembly call and pre-copulation call. We recorded six and seven syllable types from adult and young cranes separately, while the vocal frequency of adults (frequency range: 332.80-1 902.30 Hz) were significantly lower than that of young birds (frequency range: 2 229.20-5 266.70 Hz). Two kinds of syllable were confirmed for flight intension call and alarm call, and one syllable for guard call. The pre-copulation call was emitted by the female crane. Significant sonogram differences were detected between male and female cranes. The maximum frequency (F_max) of the alarm call (male: 1016.43±105.53 Hz; female: 1 817.97±512.68 Hz), the F_max of guard call (male: 1 127.00±83.05 Hz; female: 1 334.23±42.68 Hz), the frequency interval (F_interval) of alarm call (male: 485.77±42.01 Hz; female: 1 309.63±539.57 Hz), and the F_interval of guard call (male: 521.22±102.28 Hz; female: 705.88±88.42 Hz) of females were significantly higher than those of the male. And the guard call lasted longer for the female (0.41±0.06 s) than male bird (0.35±0.06 s). Our results indicated that sonogram analysis could be a useful tool determining male from female Black-necked Cranes.