台灣黑唇青斑與黃唇青斑海蛇的食物與活動時期之生態區隔研究

Food and Active Period Partition of Two Sea Kraits (Laticauda laticaudata and L. colubrina)

朱慧敏(Hui-Min Chu)

指導教授 ： 杜銘章

國立臺灣師範大學/理學院/生命科學研究所/碩士(2010年)

摘要

為了解共域於蘭嶼的黑唇青斑(Laticauda laticaudata)與黃唇青斑海蛇(L.colubrina)生態資源區隔的狀況，我於2006年8月至2008年1月在蘭嶼進行了兩種海蛇食性與活動時間調查。食性實驗分為消化道解剖法與催吐法，ㄧ共檢驗了黑唇青斑海蛇165隻次，黃唇青斑海蛇98隻次，經催吐法與消化道解剖得到黑唇青斑海蛇雄雌兩性之胃內含物各18和10件；而黃唇青斑海蛇雄雌兩性之胃內含物各11和14件。結果發現兩個種類雖皆以康吉鰻科與鯙科魚類為食，在不同種類與性別的四個類群間食物組成皆有差異，雄性黑唇青斑海蛇與兩性黃唇青斑海蛇的食物組成中，鯙科魚類所佔比率皆超過50%，其中黃唇青斑海蛇雄性完全以鯙科魚類為食，而黑唇青斑海蛇雌性則主要以康吉鰻科魚類為食。比較斐濟、萬那杜與新喀里多尼亞的黃唇青斑與黑唇青斑海蛇的食性，發現兩種海蛇在蘭嶼都有食性轉變的現象，推測兩種海蛇的食物資源利用與種間競爭有明顯的關係。
活動性實驗則發現在日周期活動上，黑唇青斑海蛇到了低溫高濕的夜晚才會開始上岸，而黃唇青斑海蛇則偏好於高溫低濕的黃昏便開始上岸活動。季節活動上兩種海蛇分別有不同的活動高峰，黑唇青斑海蛇多等到雨量開始增加的夏季才開始活動，而黃唇青斑海蛇則在雨量尚少的春季便開始活動。無論日活動週期或季節活動上，黑唇青斑海蛇皆在高濕或多雨的時期活動。兩種海蛇失水及喝水閾值實驗亦顯示黑唇青斑海蛇的水分散失速率大於黃唇青斑海蛇，顯示兩種海蛇水分散失的生理差異可能與日週期與季節性上的時間資源分配現象有關。這樣的發現也與一般蛇類活動多與溫度明顯相關的現象不同，提供了影響蛇類活動週期的另一個思考方向。

關鍵字

資源分配 ； 生態區隔 ； 黃唇青斑海蛇 ； 黑唇青斑海蛇 ； 蘭嶼 ； 食性 ； 活動周期

並列摘要

In order to understand whether two sympatric sea kraits (Laticauda laticaudata and L.colubrina) separate their food and time resources in Lanyu, Taiwan, the diet composition, daily and seasonal activity of the two species were compared in this study. I conducted this study between August 2006 and January 2008. A total of 165 L. laticaudata and 98 L.colubrina were collected. I examined the stomach contents of 18 male and 10 female of L. laticauda individuals; and that of 11 male and 14 female of L. colubrina individuals. Although both species of Laticaudines fed on congers (Congridae) and morays (Muraenidae), the dietary composition differed among the groups. The analysis showed that male L. laticaudata and both sexes of L.colubrina fed on morays (over 50%). Male L.colubrina fed on morays exclusively while female L. laticaudata fed mainly on congers. Comparing the diet of these two species in different areas (including Fiji, Vanuatu, and New Caledonia), I found both species had a shift in the diet composition. This suggested that the interspecific competition might play a role in the food resource partition of these two species.
The overall activity patterns of the two species were different. L. laticaudata moved on land at late night when the temperature was low and the relative humility was high. L.colubrina moved on land at dusk when the temperature was high and the relative humility was low. Seasonal activity was also different in these two species. L. laticaudata became abundant in summer during the rainy season. L. colubrina became abundant in spring before the rainy season. The dehydration experiment revealed that the water lose of L. laticaudata was higher than that of L.colubrina. Hence, the time resource partition of these two species might be related to their water lose. In the past, temperature was the most frequently mentioned factor that influenced the activity pattern of snakes. My study brings up a new aspect that the humidity might affect the activity pattern of snakes.

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