Cervus unicolor swinhoei




Дата канвертавання24.04.2016
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梅蘭林道地區水鹿(Cervus unicolor swinhoei)與山羌(Muntiacus reevesi micrurus)食物品質與族群的季節變化

Seasonal Changes of Food Quality and Population Dynamics of Sambar (Cervus unicolor swinhoei) and Muntjac (Muntiacus reevesi micrurus) in Mei-Lan Trail Area




研究生:梁又仁 Liang, Yu-Jen


指導教授:裴家騏 Pei, Chai-Chyi

摘要

本研究利用糞便氮元素含量(FN)來探討水鹿(Cervus unicolor swinhoei)和山羌(Muntiacus reevesi micrurus)在南台灣中海拔森林中食物品質的季節變化,以及以自動照相機和水鹿糞便計算,探討這兩種鹿科動物的攝食品質、氣象因子和族群量之間是否存在季節間的相關。

結果發現在梅蘭林道水鹿和山羌FN存在月份間的差異。水鹿FN在秋冬呈現最高而在春天最低,與當地禾本科植物秋冬的氮元素含量相符,顯示水鹿在秋冬對禾本科植物的攝食有提高的趨勢;相反的,山羌的FN在夏季最高、冬季最低,並與非禾本科草本植物與小喬木的氮元素含量呈現高度正相關,顯示此二類植物為研究區內山羌重要的食物來源。本研究顯示,梅蘭林道上全年的食物品質應皆能滿足兩種鹿科動物的營養需求,惟山羌所能獲得的食物品質可能較水鹿要高。

在族群量方面,水鹿在次生林和原始林間並無太大差別,可能是水鹿的活動範圍較大,同一族群的活動範圍涵蓋研究範圍內的兩種林型樣區;而山羌在次生林的族群量明顯高於原始林,次生林中較多的食物種類與豐富度可能是重要的原因。而不論乾溼季,兩種鹿科的相對族群量與食物品質皆無顯著的相關,反而和氣象因子有比較高的關係,顯示受降雨量和氣溫影響的新生植物供應量應該才是影響樣區內族群量變化的主要因子。

另外,雌性水鹿全年皆甚少使用本研究樣區,但雄性水鹿在濕季對本地區的使用則明顯的高於乾季。由於雌性個體在棲地選擇上較偏向安全的環境,以利分娩和哺育仔鹿,對本區的這種低度利用現象,有可能是受到狩獵活動影響;至於雄性水鹿,在濕季可能偏向選擇食物產量較高的地區而進入本區,但隨著乾季發情期開始後,則移出以尋找雌性。相反的山羌並無類似的現象,可能是因為山羌無明顯的繁殖季節,以及族群量較大、食物來源較充足所致。

關鍵字:自動相機、糞便氮元素、糞堆計算、族群量、性別比、性別隔離

Abstract

Seasonal variation in food quality and population size of sambar deer(Cervus unicolor swinhoei)and muntjac(Muntiacus reevesi micrurus in a mid-elevation forest in southern Taiwan were studied using fecal nitrogen (FN) content analysis, camera trapping and pellet-group counting.

The results show that the fecal nitrogen contents of sambar and muntjac varied throughout the year in Mei-Lan Trail. Sambar's FN highest peak appeared in autumn and winter and lowest in spring. Their FN content aligned with the seasonal changes of nitrogen content in grasses. Sambar consumes higher proportion of grasses in both autumn and winter. Muntjacs, on the other hand, showed its FN peak in summer, and lowest in winter, which significantly correlated with the seasonal variation of nitrogen content in forbs and shrub. These two kinds of food items were apparent the main food resource for muntjac in the study area. Although the food quality may be sufficient for the two cervids in Mei-Lan trail whole year-round, muntjacs might be able to acquire forages better in quality than the Sambar.

Sambar’s abundance did not differ between primary and secondary forests in the present study, which might because of the sambar population has larger home range and the same population covered both study sites of the two forest types. The abundance of muntjacs, however, is higher in the secondary forest, probably due to its abundant food resources. Present study also showed that the variation of food quality did not affect the number of deer used the study area both in dry and wet season. The number of deer used the study area, however, were positively affected by higher precipitation and temperature. Therefore, compared with the food quality, the quantity of fresh food availability may be a more important factor to affect the use of the habitat by deer.

The study area was apparently a wet season range for male sambar deer when the food supply are abundant, females rarely used it. The moderated hunting activity presented in the study area might cause their low utilization of the area, because female deer tends to stay in safer habitat so they can calve and lactate. Male sambar deer left the study area during dry season was must likely for searching for mates. In contrast, muntjac population was stable during the study period, non-seasonal breeder, larger population size and abundant food resources in the study area were probable reasons.



Keywords:Camera trapper, fecal nitrogen, pellet-group count, population size, sex ratio, sexual segregation


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