菊池氏龜殼花的食性及偏好

Food habits and prey chemical preference of Taiwan mountain pit-viper(Trimeresurus gracilis)

林家帆(Jia-Fan Lin)

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(2004年)

摘要

摘要
為了瞭解台灣特有種蛇類菊池氏龜殼花的食性，我蒐集152隻蛇的胃內含物，有胃內含物的比例是18.4 %，88.5 %的獵物由頭部被消化，獵物與蛇的體重比為0.084~0.807，獵物重與蛇的吻肛長成正相關。將排遺及胃內含物合併分析 (prey items = 107)，其獵物種類為哺乳類 (33 %)、爬行類 (32 %) 及兩生類 (7 %)，屬於次級獵物的節肢動物 (25 %)，另有3 %未鑑定出。由食性資料可知成蛇的獵物多為哺乳類，未成熟蛇的獵物多為蜥蜴類及兩生類，攝食內溫動物的個體其吻肛長明顯大於攝食外溫動物的個體，因此由幼體到成體具有食性轉變的現象。成蛇的獵物多為哺乳類 (41.4 %)，但雌性成體明顯比雄性成體攝食較多體型較大的齧齒類，可看出食物組成在性別上的差異。
暸解其食性組成後，使用前人的棉花棒測試法 (Cotton swab test) 進一步檢測 (1) 新生幼蛇是否會辨別獵物氣味 (2) 新生幼蛇對獵物氣味的偏好是否不同？結果發現新生幼蛇能分辨獵物 (台灣蜓蜥) 及非獵物 (雙線蛞蝓) 的氣味，且顯著偏好台灣蜓蜥的氣味。我認為視覺對蛇類的捕食行為也很重要，因此設計一動態棉花棒測試法，並與靜態的棉花棒測試法比較，結果顯示動態棉花棒較能檢測成蛇對氣味的偏好，並使用此法再檢測新生幼蛇、亞成蛇及成蛇對獵物氣味是否有不同偏好？我選用七種獵物氣味進行偏好測試，分別是哺乳類：台灣森鼠及台灣長尾鼩，兩生類：阿里山山椒魚及梭德氏赤蛙，蜥蜴類：台灣蜓蜥、麗紋石龍子及雪山草蜥。結果顯示成蛇偏好兩生類與哺乳類的氣味勝於蜥蜴類的氣味，其中最偏好阿里山山椒魚的氣味；亞成蛇偏好台灣蜓蜥的氣味，其次為阿里山山椒魚；新生幼蛇偏好台灣蜓蜥的氣味，其次為麗紋石龍子的氣味。結果可知菊池氏龜殼花由幼體到成體偏好不同獵物氣味，且幼體對氣味偏好的結果與野外食性相符，成體及亞成體則否。

關鍵字

菊池氏龜殼花、食性、棉花棒測試法、化學氣味偏好

並列摘要

Abstract
I checked the stomach contents of Taiwan mountain pit-viper (Trimeresurus gracilis), an endemic species, and found only 28 (18.4 %, N = 152 ) snakes contained preys. Among these, 88.5 % preys were swallowed head-first. Prey-predator mass ratios ranged from 0.084 - 0.807, and prey mass was positively correlated with predator snout-vent length. When I combined the stomach contents and fecal remains, I identified 107 preys including 33 % mammals, 32 % reptiles, 7 % amphibians, 25 % arthropods (probably secondary prey) and 3 % unidentified preys. Mature snakes often ate mammals while immature snakes ate lizards and amphibians. The snout-vent length of individuals that consumed endothermic preys were significantly larger than those that consumed ectotherms. There was an ontogenetic dietary shift. Adult snakes preyed primary on mammals (41.4 %). Adult females preyed most frequently on rodents (45.4 %) whereas adult males preyed most frequently on insectivores (59.3 %). There was a dietary difference between sexes.
I used cotton swab smeared with prey scents to determine whether the newborn T. gracilis can discriminate prey chemical cues. I also checked whether these snakes preferred some of these prey scents than others. A greater chemosensory response to the scent of skink than to that of slug indicated that T. gracilis was able to discriminate the prey chemical cues. Newborn snakes also showed a stronger response to Sphenomorphus taiwanensis scent than other prey scents. In rattlesnakes, visual cue plays an important role in eliciting a successful predatory strike. I designed a moving cotton swab method and compared it with stationary cotton swab method. I found moving cotton swab method was a better way to test the prey chemical preference especially for adult snakes. Then, I used the moving swab method to test whether neonates, sub-adult and adult snakes preferred different prey chemical cues. I presented chemical stimuli of seven preys that coexist with these snakes including mammals: Apodemus semotus and Soriculus fumidus, amphibians: Rana sauteri and Hynobius arisanesis, lizards: Takydormus hsuehshanesis, Sphenomorphus taiwanensis and Eumeces elegans. I found adult snakes preferred scents of amphibians and mammals than scents of lizards, and they liked the scent of Hynobius arisanesis mostly. Sub-adult preferred the scent of Sphenomorphus taiwanensis mostly and secondly the scent of Hynobius arisanesis. Neonates preferred the scent of Sphenomorphus taiwanensis mostly and secondly the scent of Eumeces elegans. There was an ontogenetic prey chemical preference shift in T. gracilis. The prey scent preference of neonates corresponded to their natural diets, but the preference of adults and sub-adults didn’t.

並列關鍵字

Trimeresurus gracilis、food habits、cotton swab test、chemical preference