南投地區台灣葉鼻蝠之族群變動與活動模式

Population Dynamics and Activity Patterns of the Formosan Leaf-nosed Bat (Hipposideros terasensis) in Nantou Area

為瞭解台灣葉鼻蝠群集年週期之族群變動，自1994年6月至1996年5月間，以估算每月群集數量的方式進行南投地區兩處台灣葉鼻蝠群集之研究；同時，為瞭解其一日之活動模式，於1995年7月至1996年6月間，對該兩群集進行每月一次之黃昏出洞、夜間活動與清晨返洞觀察記錄。兩個群集之一在5、6月間有幼蝠生產，視為生殖群集，另一群集則無生殖現象。整年觀之，兩個群集之族群量變動趨勢大致類似：每年2、3月間，蝙蝠出現於棲所；11月間群集量明顯遞減至全部離洞；12月至翌年2月間均不見蝙蝠存留於棲所內。然而，在3～11月間每月群集量的變動，兩處則有所差異，達到高峰期的月份與數量均不同。非生殖群集的蝙蝠開始離洞渡冬的時機較早，較生殖群集提早約兩個月，兩處之群集量在9月間互為消長。蝙蝠季節性的遷移、棲所間的移動停棲以及生殖期幼蝠的產生應是影響每月族群數量變動的主要因子。在活動模式方面，台灣葉鼻蝠黃昏飛離、翌日黎明飛返棲所的時間明顯受當時的光照強度影響，與日落與日出的時間相關性顯著。夜間活動模式依每小時在棲所外活動之個體數比率，呈現出單峰型或雙峰型兩類型式；生殖群集與非生殖群集呈現的類型不同，尤其是產後之哺育期（7至9月）最為明顯。將台灣葉鼻蝠黃昏出洞時機與高頭蝠與東亞家蝠作一比較發現，台灣葉鼻蝠出洞時的光照強度明顯地偏低許多，絕大部分個體幾乎是天黑後始離洞活動。 A study of the population dynamics of two roosts of the Formosan leaf-nosed bat(Hipposideros terasensis) in Nan-tou area, Central Taiwan, was conducted from June1994 to May 1996. These roosts included a non-breeding colony and a colony withbreeding activity between May and June. The activity patterns of these two colonies werealso investigated between July 1995 and June 1996. The population dynamics of bothcolonies presented a similar trend throughout the year. In both cases, bats settled in theroosts during February and March and left for hibernation during November andDecember. No bat stayed in either roost from December to next February. However,during March to November, the changes of these two colonies size showed differentpatterns. In the non-breeding colony, bat arrived to the roost in February, and the numberof individual increased quickly in March to the peak number (more than 600 bats) of thewhole year, and then hold a colony size of couple hundred bats in the next several monthsuntil September. The number of colony size decreased quickly during September toNovember. On the other hand, the size of the breeding colony increased gradually fromMarch to May, and showed a peak colony size in June and July. The most number of thewhole year appeared in September and October (but less than 100 bats). The number ofbats decreased quickly in November. However, the time of most bats in the breedingcolony left their roost was about two months late than in the non-breeding colony. Thefactors primarily affecting the change of population size were (1) bats seasonal migration(2) short term movement between roosts, and (3) birth of young for the breeding colonyonly. The study of activity pattern showed that the timing of activities were significantlycorrelated to the time of sunset and sunrise, as well as light intensity. The two coloniesshowed either a unimodal or bimodal activity pattern throughout the night in differentmonths. The difference may be mainly due to the breeding state of colonies, especiallyduring breeding season. The light intensity of emergence of Hipposideros terasensis atdusk was the lowest when compared with Scotophilus kuklii and Pipistrellus abramus.