台灣西岸中華白海豚活動範圍與社群結構之變化

Temporal change in range use and social structure of Indo-Pacific humpback dolphins (Sousa chinensis) off western Taiwan

侯雯(Wen Hou)

指導教授 ： 周蓮香

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201700632

摘要

台灣西岸(大多水深小於25米)的中華白海豚族群，數量小(少於80隻)，是嚴重瀕危，有長期監測其活動範圍以及社群動態的必要性，提供保育經營的重要基礎。本研究源於2008-2014年間海上調查的中華白海豚目擊紀錄和攝影，經照片辨識後，分成前期(2008-2010)以及後期(2012-2014)去追蹤前後期中各目擊10次以上的33隻個體，分析活動範圍與社群動態，內容包含兩大部分:第一部分以模擬移動路徑並應用核密度函數法(Line-based kernel density estimation) 分析每隻個體核心與家域活動範圍。結果顯示(1)原居住在南邊的16 隻個體中有12隻個體的核心活動範圍與家域範圍有明顯往北邊移動的趨勢;(2)改變核心和家域活動範圍的個體皆多為較年輕的個體。第二部分則是以半權重關聯指標(half-weight association index)，分層群聚分析(hierarchical cluster analysis)以及標準滯後關聯比(standard lagged association rate)分析其社交社群的結構。結果顯示(1)前期明顯分為兩個社交群體(social groups):北社交群17隻以及南社交群16隻，後期則轉變三社交群:北社交群10隻、南社交群12隻以及中社交群11隻;(2)新組成的中社交群，7隻來自原北社交群以及4隻來自原南社交群，後者3隻個體曾是育幼的母親;(3)中社交群的組員個體的活動範圍變化有社群差異，來自原北社交群者無顯著改變，而來自南社交群皆為單核心區且其核心區有明顯北移現象。原南社交群有些個體具有兩個核心區者，其一核心區留在原處，而另一核心區則有位移或/且擴張其家域範圍至北邊。中華白海豚兩兩個體間的關聯指標顯示，個體間關係為非隨機且有特定偏好，其說明了中華海豚社群結構為穩定但個體間具有高流動性交流。總結，台灣的中華白海豚的活動範圍與社交社群結構改變兩者間有交互關係。未來應加入食餌資源之研究以深入了解海豚活動範圍與社群結構之時空變化與環境因子及生活史的關係。

關鍵字

中華白海豚 ； 核心區 ； 家域範圍 ； 核密度函數 ； 照片辨識 ； 社群結構與動態

並列摘要

The population of Indo-Pacific humpback dolphins in western Taiwan has been claimed as “Critically Endangered” due to its small population size which less than 80 individuals. Thus, it is critical to execute a long-term monitoring program on its ranging pattern and social dynamics for conservation management purpose. Based on photo-identification (photo-ID) sighted dolphins in 2008-2014 and, 33 individuals which had been sighted no less than ten times in each period (2008-2010 and 2012-2014) were included for analyzing temporal variation their ranging patterns and social structure. In the first part, line-based kernel density estimation was applied for analyzing the core area and home range of dolphins and results indicated that (1) 12 out of 16 individuals of the southern community shifted their core area to northern area during the 2nd period. (2) Most individuals with shifted home range were in relative younger age stages. In the second part, half –weight association index, hierarchical cluster analysis and standard lagged association rate analysis of the population were revealed that (1) Two social groups (17 and 16 individuals in the first period changed into three social groups in 2nd period with a new group (11 individuals ) in the middle between northern and southern group (10 and 12 individuals). (2) The newly formed middle groups consisted with seven dolphins from northern group and five dolphins from southern groups (three dolphins were sexually matured females). (3) The ranging pattern of middle group members varied with their original background, the ones from northern social group did not change their range use significantly, while the ones from southern transients that joined the new group were all own one core area and which shifted into northern area. In contrast, for those individuals remained at south had two core areas, one core area remained original area and the other shifted to northern area. The social bonding of Indo-Pacific humpback dolphin is non-random casual association and indicate the fluidity of social dynamics. In summary, the temporal changes in ranging pattern and social structures were the outcome of interactions. Specific research in life history as well as fish prey resource are requested to be conducted in the future.

並列關鍵字

Indo-Pacific humpback dolphins ； core area ； home range ； kernel density estimation ； photo-identification ； social structure and dynamics

參考文獻

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