碩士 / 國立臺灣大學 / 森林環境暨資源學研究所 / 104 / Mixed-species bird flock (MSF) is a phenomenon of two or more bird species moving together in same direction while foraging and might benefit participants by improving foraging efficiency or reducing risk of predation. I investigated the effects of environmental factors on structure of MSFs in high-elevation areas in Hehuanshan and Tataka of central Taiwan, from September, 2013 to December, 2014. Five different vegetation types were selected: Yushan Cane steppe (Yushania niitakayamensis), Taiwan Red Pine forest (Pinus taiwanesis), Taiwan Hemlock forest (Tsuga chinensis), Taiwan Spruce forest (Picea morrisonicola) and Taiwan White Fir forest (Abies kawakamii). Every month, I spent at least 5 hours in each vegetation type recording MSFs by line transect method. When encountering an MSF, I enumerated the number of each participating species and designated the nuclear species. I also surveyed local bird communities by point counts method at the same study plots. Air temperature was recorded by a pendant temperature data logger located in each vegetation type. Twenty-four bird species and a mammal species participated in the MSFs, with averages of 3.9±1.6 species and 26.3±21.9 individuals per flock (n=129). The number of species in MSFs positively correlated with flock size. Insectivores dominated the MSFs and mostly had a significantly higher flocking propensity than herbivores. Birds with similar foraging niches tended to flock together. Species composition of MSFs can be divided into two major types: canopy flock and understory flock. Flamecrest (Regulus goodfellowi) and Taiwan Barwing (Actinodura morrisoniana) were the most common nuclear species in canopy and understory flocks, respectively. Local dominant species were more likely to be the nuclear species in the MSFs. Most of nuclear species expanded their foraging niches in MSFs. Moreover, canopy height and vertical foliage structure of vegetation had strong influence on species composition of MSFs. Canopy and understory flocks usually came to form a ”mega flock” in Taiwan Red Pine forest that has a relatively lower canopy height. Flock size decreased with increasing elevation. Most of the flocks were recorded in non-breeding season, and flocking propensity varied with season accordingly. The number of MSFs and species participation rate increased with decreasing temperature. To sum up, the formation of MSFs in high elevation areas of Taiwan was strongly influenced by environmental condition. Environmental factors determine the distribution and abundance of birds, which further influence species composition, flock size, role of species, flocking propensity and flocking frequency. Vertical foliage structure of vegetation also affects distribution and foraging level of bird species, which in turn controls formation of MSFs. Improving foraging efficiency should be the main reason of forming MSFs in high elevation areas of Taiwan. With fewer food resources available in winters, several bird species flock and forage together to overcome the food limitation.
| Identifer | oai:union.ndltd.org:TW/104NTU05359024 |
| Date | January 2015 |
| Creators | Chun-Chieh Liao, 廖俊傑 |
| Contributors | Tzung-Su Ding, Chao-Chieh Chen, 丁宗蘇, 陳炤杰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 89 |
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