碩士 / 國立東華大學 / 自然資源與環境學系 / 99 / Bird song plays an important role in communication. In order to effectively transmit messages, birds tend to choose a favorable mode of transmission. Furthermore, acoustic variations of bird songs among populations may be formed as a result of the appearance of geographical barriers, the increase of distance between populations or different habitats. The Rufous-capped Babbler (Stachyris ruficeps) is a resident bird species in Taiwan, with a wide elevational distribution from sea level to 3000m. Its song is composed of simple whistling-like notes. In this study, I analyzed the songs of Rufous-capped Babblers from both sides of the Central Mountain Range with the aim to find if the geographical barrier or distance and elevational difference of environment would cause acoustic variations of their songs. I recorded the songs of 278 individuals from plots along Central Cross-Island Highway, Wu-She Supply branch Highway (Tai #14 Highway) and Su-Hua Highway (Tai #9 Highway). The parameters of these songs were measured from the sound spectrum. I measured seven acoustic parameters in which five are frequency-related and two are time-related. The results of simple regression analysis showed that in the eastern side of the Central Mountain Range, elevational gradient alone explained 46%, 35% and 23% of variations in respect to end frequency, the highest frequency and the lowest frequency, respectively, but offered less explanation to the variations of the duration, the bandwidth of songs and start frequency. The results of songs from the western side of The Central Mountain Range showed similar pattern, with elevational gradient explained 48% of variation to the lowest frequency, 32% of variation to end frequency, 17% of variation to start frequency and 15% of variation to the highest frequency. It also explained less but significant variations of duration and bandwidth. Comparing songs from both sides of the Range found no significant difference in all of the acoustic parameters, and no significant difference in all parameters between songs recorded from the same elevation. These findings indicated that mountain barrier and geographical distance did not result to significant difference in the songs of the Red-capped Babblers and showed that elevational gradient is the main factor causing variations in the songs of the Red-capped Babblers. In addition, we measured the morphological traits of 81 male Rufous-capped Babblers captured in the eastern slope of the Range during the same study period and found a significant correlation between their body size and elevation. Based on related researches, body size would affect song frequency, therefore, we concluded that the elevation would affect the songs of the Red-capped Babbler through the effect on the body size, as the elevation getting higher, the birds there become larger in body size and sing in lower frequency.
| Identifer | oai:union.ndltd.org:TW/099NDHU5399006 |
| Date | January 2011 |
| Creators | Pei-Chun Shih, 施佩君 |
| Contributors | Yu-Cheng Hsu, 許育誠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 49 |
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