屏東科技大學校園內斑龜族群組成與移動模式

Population Composition and Movement Patterns of the Chinese Stripe-necked Turtle (Mauremys sinensis) on a Suburban University Campus in Southern Taiwan.

Huang(Ling)

指導教授 ： 陳添喜

國立屏東科技大學/獸醫學院/野生動物保育研究所/碩士(2020年)

https://doi.org/10.6346/NPUST202000091

摘要

隨著低海拔地區快速都市化發展及土地利用型式的改變，許多野生動物也因此面臨棲地消失與破碎化的威脅。水棲或半水棲淡水龜需要利用水域與陸域棲地的生活史特性，造成全球多數種類族群長期存續受到人為棲地改變的負面影響。斑龜(Mauremys sinensis)是台灣低海拔水域環境常見的淡水龜，其棲息環境受人為改變尤為常見，對其族群存續已造成不利影響。本研究由2018年3月至2019年9月間於屏東科技大學校園內利用重複捕捉標放及無線電追蹤進行野生斑龜族群組成、移動模式、活動範圍與棲地利用之比較，以瞭解棲地人為改變程度明顯差異的二處樣區，包括道路與人工構造物密度，可能對族群與棲地利用產生影響。本研究計捕獲712隻斑龜、2隻中華鱉(Pelodiscus sinensis)及外來種4隻巴西龜(Trachemys scripta elegans)及1隻真鱷龜(Macrochelys temminckii)。捕獲斑龜個體組成中雄龜占61.9%、雌龜23.7%與未判定性別的幼龜14.3%；達到產卵體型(>19.0 cm CL)雌龜僅占6.5%，雌龜及幼龜所占比例較低。其性別比有明顯偏離性別平衡，棲地人為改變程度不同的二處樣區性別比皆明顯偏向雄龜，又以改變程度較低樣區雄龜所占比例較高，但可能與不同性別捕獲率的差異有關。雌龜背甲長及體重皆顯著大於雄龜，於棲地人為改變程度較高的樣區所捕獲雄龜平均背甲長及體重皆大於棲地人為改變程度較低的樣區所捕獲之雄龜。捕獲上標個體有298隻重複被捕獲，於其他水域重複捕獲有93隻，於人為改變程度較低的樣區遷移至其他水域被重複捕獲之頻度較高。在20隻無線電追蹤個體中，有發現60%追蹤個體之定位點與原捕獲地點直線距離超過200公尺。於棲地人為改變程度較低的樣區離原捕獲處有較長距離的移動，有70%追蹤個體定位點與原捕獲地點距離超過200公尺且皆在多處水域間移動；於棲地人為改變程度較高的樣區僅50%追蹤個體定位點與原捕獲地點距離超過200公尺，其中1隻個體僅於狹長型溝渠1處水域多次來回移動。在9月至11月間多數追蹤雄龜個體出現在不同水域間有較長距離移動；但雌龜則多為短距離移動，定位點與原捕獲地點距離多數未超過200公尺。無線電追蹤雄龜個體的活動範圍有明顯大於雌龜，於二處不同樣區雌雄個體皆無顯著差異。定位點出現頻度最高之棲地類型為水池環境，為51.3%，但於二處樣區利用棲地類型略有差異，出現頻度最高棲地類型分別為溝渠(45.6%)及水池(66.6%)。重複捕獲及無線追蹤結果皆顯示斑龜利用陸域環境進行不同水域間移動極頻繁，水域周邊或移動通道的人為改變會增加其生存風險，應保留合適遷移通道及鄰近陸域棲息地，以維護其族群之存續。

關鍵字

斑龜 ； 棲地改變 ； 族群組成 ； 移動模式 ； 活動範圍

並列摘要

Due to the rapid development and urbanization in the low-elevation areas, many wildlife species inhabiting in highly human-altered habitats have been threatened as results of habitat loss and fragmentation. It is especially true for the aquatic and semi-aquatic freshwater turtles, which use both aquatic and terrestrial habitat to meet the needs for different life history stages. In Taiwan, the Chinese stripe-necked turtle (Mauremys sinensis) is a common species in the low-level aquatic habitats, however the urbanization and dramatic changes in land use also adverse effects on the long-term persistence of it populations. I have conducted a mark-recapture and radio-tracking study on the M. sinensis population on a suburban university campus to investigate the differences in population composition, movement patterns, home ranges and habitat use in two areas with different degree in habitat alteration. From March 2018 to September 2019, I have captured 712 M. sinensis, two Chinese softshell turtles (Pelodiscus sinensis) and two introduced species, including four red-eared sliders (Trachemys scripta elegans) and one alligator snapping turtle (Macrochelys temminckii). Among M. sinensis captured, 61.9% were males, 23.7% females and 14.3% unsexed juveniles; female and unsexed juveniles represent relatively minor proportions in the population. Females with body size larger than the smallest gravid individual occupied 6.5% only. Overall, the sex ratio was significantly skewed toward males, and the male-biased sex ratio was much higher in less-modified habitat. Similar to previous studies, there showed a sexual size dimorphism in my studied population; females were significantly larger than males in both of carapace lengths and body weights. Based on mark-recapture results, a total of 298 turtles were recaptured more than one times in aquatic habitats; among them, 93 were from the sites different from the initial captures. There were the proportions of non-residents much higher in less-modified habitat. In my results of radio-tracking, 40% of the tracked individuals moved within a relatively small area with straight-line distance between relocations and initial capture points shorter than 200 meters. In the habitat with lower degree of human alteration, turtles moved more frequently and in longer distance and 70% of the tracked individuals with straight-line distance between relocations and initial capture points longer than 200 meters; in the area with degree of human alteration, most turtles were relatively residential and 50% of the tracked individuals with distance between relocations and initial capture points shorter than 200 meters. During September and November, most tracked males made relatively long-distance movements among aquatic bodies, coinciding with the dry season, meanwhile females were relatively residential, making short-distance movements in the same water bodies or adjacent habitats. The home ranges of tracked males were larger than those of females, but there were no differences between two areas in both sexes. Overall, the tracked turtles used ponds most frequently among different habitat types, representing 51.3% of the relocations. In the higher human-altered habitat, 45.6% of relocations presented in ditch and 66.6% in ponds in the lower human-altered habitat. The population composition, movements and habitat use of M. sinensis have been affected by anthropological habitat alteration. My results of mark-recapture and radio-tracking studies indicated that M. sinensis used terrestrial habitat frequently when moving among different aquatic habitats. The alteration or modification in the areas adjacent to water bodies or corridors used by the turtles will increase the risk of mortality. The protection or reservation of corridors among suitable aquatic habitats and the terrestrial habitat adjacent to water bodies should be considered for the persistence of M. sinensis population.

並列關鍵字

Chinese stripe-necked turtle ； Habitat change ； Population composition ； Movement patterns ； Home range

參考文獻

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