台灣鈍頭蛇(Pareas formosensis)對食物氣味之偏好及追蹤蛞蝓黏液之探討
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2005
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覓食搜索是影響蛇類生存的重要因素，因此是非常重要及普遍存在的行為。台灣鈍頭蛇（Pareas formosensis）是台灣特有的種類，並且具有相當特殊的食性，目前已知會吃食某些蛞蝓與蝸牛，我以棉花棒沾上食物氣味測試鈍頭蛇對於食物化學氣味的反應程度，結果顯示他們顯著偏好蛞蝓的氣味，由於蛞蝓與蝸牛在爬行後會留下一道相當明顯的黏液痕跡，台灣鈍頭蛇可能會利用痕跡追蹤蛞蝓，我用Y型槽測試台灣鈍頭蛇在有光及無光的情況下，是否會追蹤黏液痕跡以了解台灣鈍頭蛇視覺及化學感受對於痕跡搜索的重要性，結果顯示鈍頭蛇對蛞蝓腹部黏液痕跡的追蹤正確率顯著偏離逢機的50％，且在完全黑暗的情況下追蹤黏液的正確率並不會受到影響；另外，在光亮且開闊的環境下測試鈍頭蛇是否仍然會追蹤黏液，並讓黏液放置一段時間後再測試，結果顯示，不管蛞蝓的腹部黏液是直線或塗成歪型，鈍頭蛇都能正確追蹤新鮮的腹部黏液且其正確率都顯著大於對照組的水，但若將黏液放置在通風處15分鐘與30分鐘（溼度50 ± 10，溫度20 ± 2 C）後再測試，則鈍頭蛇能正確追蹤腹部黏液的比例明顯下降，而能正確追蹤背部黏液的比例雖也下降，但未達顯著標準。
Food searching is an common and important behavior in snakes. Taiwan slug snake (Pareas formosensis), an endemic species in Taiwan, is a specialist, which prey on slugs and snails. In this study, I checked the preference of the snakes to prey orders, and tested whether they could follow the mucus-trail of a slug. The snakes preferred the chemical scents of slugs which were smeared on the cotton swabs. The correct trailing rates of snakes to slug’s venter mucus in Y-maze were significantly higher than the rate of random (50%). The correct trailing rates in dark condition were not significantly different from that of dim (1-2 lux) condition. This suggested that, the snakes might utilize the chemical but not visual cues from mucus to trail the prey. The snakes could trail the mucus both in straight and curved shape. The correctly trailing rates of snakes to mucus of slug’s venter which has been ventilated at 50% RH, 20 ± 2C for 15 or 30 mins were significantly lower than fresh mucus. However, there was no significant difference of trailing slugs’ backside mucus among different ventilation times.
Food searching is an common and important behavior in snakes. Taiwan slug snake (Pareas formosensis), an endemic species in Taiwan, is a specialist, which prey on slugs and snails. In this study, I checked the preference of the snakes to prey orders, and tested whether they could follow the mucus-trail of a slug. The snakes preferred the chemical scents of slugs which were smeared on the cotton swabs. The correct trailing rates of snakes to slug’s venter mucus in Y-maze were significantly higher than the rate of random (50%). The correct trailing rates in dark condition were not significantly different from that of dim (1-2 lux) condition. This suggested that, the snakes might utilize the chemical but not visual cues from mucus to trail the prey. The snakes could trail the mucus both in straight and curved shape. The correctly trailing rates of snakes to mucus of slug’s venter which has been ventilated at 50% RH, 20 ± 2C for 15 or 30 mins were significantly lower than fresh mucus. However, there was no significant difference of trailing slugs’ backside mucus among different ventilation times.
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台灣鈍頭蛇, 追蹤黏液, 化學偏好, Pareas formosensis, trail mucus, chemical preference