Monitoring butterflies in Shimentai National Natural Reserve石門台国立自然保護区におけるチョウ類のモニタリング

Authors著者名

Min Wang王敏1), Osamu Yata矢田脩2), Xiaoling Fan茫駁凌1), Mingyi Tian田明文1)

Affiliations著者所属

  1. 1) Laboratory of Insect Ecology, South China Agricultural University
  2. 2) Laboratory of Biosystematics and Biodiversity, Faculty of Social and Cultural Studies, Kyushu University

ABSTRACT要約

Monitoring of butterflies by means of transect recording method was conducted from Oct. 1, 2002 to Sep. 30, 2003 in Shimentai Nature Reserve (E113゜01′11″~113゜46′22″, N24゜17′49″~24゜31′02″, 82,260km2), Guangdong Province under the support from PRO NATURA FUND.

A total of 5,237 individuals belonging to 162 species of 11 families were confirmed during the period. The number of species represents 45.5% of the total species thus far recorded in the reserve (356 ssp.) from the previous survey (“A survey on biodiversity and conservation of butterflies in Shimentai Provincial Natural Reserve"; Oct. 1, 2001 to Sep. 30, 2002) . In addition, 8 species were recorded for the first time to the reserve, i.e., (Athyma zeroca, Nymphalidae; Lethe mekara, Mycalesis panthaka, Ypthima multistriata, Y. tappana, Satyridae; Tagiades menaka, Celaenorrhinus sp., Pithaura marsena, P. stramineipennis, Hesperiidae).

Considering the habitat preference of butterflies, the families Lycaenidae and Hesperiidae tended to contain more species with narrower preference and thus more sensitive to the environmental disturbance than the families Papilionidae, Pieridae and Danaidae.

The above results suggest that, for butterfly conservation, monitoring works in the reserve should be continued in order to accumulate data based on accurate identification over a long period of time.


中国南部の広東省、石門台(シメンタイ)国立自然保護区(東経113°01'~113°46'、北緯24°17'~24°31'、面積822,260km2)において2002年10月~2003年9月にかけて、チョウの保全を目的として、トランセクト法によりチョウのモニタリングの実施した。石門台自然保護区の中でも特によく保存されたコア地域となっている「石門台」に全長12kmの調査ルートを設定し、さらに環境の違いによってこのルートを5つの区間(A~E、各区間2~2.5km)に分けた。調査にあたっては、通常の「トランセクト法(ルートセンサス法)」を用い、2002年10月~2003年9月にかけて12月~1月は2週間に1回、その他の月は週1回の間隔で実施した。調査の実施にあたっては、保護区の管理スタッフや地域の生徒、学生にも調査法を普及、指導しながら調査に参加させた。

その結果、この期間中に合計162種、5,237個体を確認した。これは、我々が2001年度PRO NATURA FUNDの助成による石門台自然保護区ににおけるチョウ相の調査(2001年10月~2002年9月)によって得られた総種数(356種)の45.5%にあたる。今回、さらに8種のチョウ(Athyma zeroca, Nymphalidae;Lethe mekara, Mycalesis panthaka, Ypthima multistriata, Y.tappana, Celaenorrhinus sp., Satyridae; Tagiades menaka, Pithaura marsena, P.stramineipennis, Hesperiidae)が同保護区で新しく記録された。

種数、個体数とも5月に最大ピーク、1月に最小ピークを迎える。区間Eの個体数、種数が他の区間より常に多かった。A区間も総じてEに次いで多いが、シーズン(雨期にあたる4~7月)は各区間の差がほとんどなくなった。アゲハチョウ、シロチョウ、マダラチョウの各科は総じて個体数の多い種を多く含み、一方、シジミチョウ、セセリチョウ科は個体数の少ない種が多い傾向がある。生息地選好性の点から考慮すると、シジミチョウ科とセセリチョウ科においては、アゲハチョウ、シロチョウ、マダラチョウ科に比べて、生息地選好性の幅が狭く環境の変化に敏感な種がより多く含まれると考えられる。

以上の結果から、チョウの保全の方策の一つとして正確な同定作業にもとづく長期間にわたるデータの集積を継続するモニタリングが必要であることが強く示唆された。

(推薦者:矢田脩)

1. INTRODUCTION

Butterflies, the best known group of insects, are sensitive to environmental changes and can serve as valuable bio-indicator supplying indispensable information on the state and evolution of the environment.

Monitoring butterflies as a successful scheme dates back to 1970's in UK (Pollard & Yates 1993, etc.). This method has quickly spread to other countries due to its simplicity and effectiveness and is now widely conducted in many countries such as Britain and Japan.

During our last project of PRO NATURA FUND 2001, we got basic data on species diversity of butterflies in Shimentai Nature Reserve. So the present project aims to monitor butterflies at selected places for their conservation. Such an activity has never been conducted in S. China and will contribute greatly to the spreading of popular science.

2. STUDY SITES AND METHODS

(1) Study Site (Fig1):

Considering the accommodation for transportation of recorders, the Shimentai Substation was selected as monitoring site in the reserve. The surrounding areas have been developed for ecological tours with "Stone Gate", as sightseeing spot. The transect route starts from Shimentai Substation and runs northwestwardly about 12km along a path leading to Shimentai Village. Although the width of the route varies from about 1m in shady places to 8~10m in some open spaces, it measures 3~5m in most parts, which is suitable for monitoring butterflies.

The transect route was divided into 5 sections according to vegetations, open spaces, nectar flowers and habitats.

Section A:
Starts from the Shimentai Substation and runs along a small sub-path leading to the summit of a mountain in the west. There are open places around the substation, with streaks and cultivated fields. This section is rather steep at the entrance of the route, passes by some coniferous plantations and enters a secondary forest.
Section B:
Starts from the sub path and, after passing through secondary forests, a small part of coniferous tree mixed with bamboos and a stream with broad open spaces, ends at about 200m northward of the stream. This section is almost completely within a secondary forest apart from a conifer-bamboo region and the open spaces along the stream are good habitats for butterflies.
Section C:
Starts from the end of section B and, after passing by secondary forest with some parts of naked slope of stone where the surface of the stone is wetted by very small springs, ends before a curved angle.
Section D:
Starts from about 200m before the curved angle, passes along a secondary forest, and ends at a small hill. This section is complicated in habitats with some grassland.
Section E:
Starts from a small hill, passes downwardly by a secondary forest and some vegetable fields and reaches at Shimentai Village and its vicinity. This section is the most open places within the core area of the reserve, and cultivated lands mainly for vegetables are rather fragmentary. The Village is small with about 20 families there. There is a broader river passing by the village.

Fig 1. Moritoring site in Shimentai Nature Reserve with the route (12km) divided into A,B,C,D and E sections (2~2.5km each).

Fig1 Moritoring site in Shimentai Nature Reserve with the route (12km) divided into A,B,C,D and E sections (2~2.5km each)

(2) Methodology

1) Monitoring tools

Monitoring paper sheet (recording form), insect net, watch, ballpoint pen or pencil, thermometer, camera, field glasses, pictorial guidebook for butterflies, etc.

2) Frequency of monitoring

At least 2 successful recordings per month were planned during the project period. For the autumn and winter season, this plan was easy to be accomplished since the weather condition is rather good. In the spring and summer, 3~4 tries per month were needed to meet the requirement because of rainy and heavily cloudy weather. The number of butterflies obtained from 2 successful monitoring is added together to obtain the number per month for each species.

3) Butterflies monitoring, collecting and identification

The method used in our monitoring is "transect recording" (Fig2), a method widely conducted in European countries and Japan. A monitoring walk was done between 9:00 AM and 3:00 PM.

Fig2 Transect recording (after Yata 1996)

Fig2 Transect recording (after Yata 1996)

A recording table of butterflies probably seen along the monitoring route was compiled in advance. At the beginning of monitoring, the temperature and weather condition (windy, sunshine or cloudy) were recorded. The recorders, walking along the route at a steady pace, counted all the species seen within the width and height of about 5m and within a range about 5m ahead of the recorders.

Due to the long distance of the route, recorders of 2 groups were started simultaneously from the both ends, and met together at section C.

Unlike the situation in England, butterflies in Shimentai were not easy to be identified during the recording time except for some large and common species. So the recorders always had to catch butterflies for confirmation. Some species were released after identification, but some others, particularly those of the families Lycaenidae and Hesperiidae, that couldn't be identified in the field, were taken back to the laboratory.

Identification of butterflies was mainly based on Chou (1994, 1998), Osada et al. (1999), Gu & Chen(1997), Wang & Fan (2002), and D'Abrera (1982~1986).

3. RESULTS AND DISCUSSION

(1) Butterflies Number (Fig3)

During our survey, 5,237 individuals of butterflies were confirmed. About 200 individuals mainly in the families Lycaenidae and Hesperiidae could not be identified, however, because they were flying high in the sky.

At the family level, the recorded numbers of butterflies are as follows: Papilionidae (971), Pieridae (1,087), Danaidae (392), Amathusiidae (81), Satyridae (855), Nymphalidae (971), Acraeidae (18), Libytheidae (27), Riodinidae (103), Lycaenidae (367), Hesperiidae (365).

These data are presented in Fig3. It is seen from the Fig3 that 4 families are predominant: Pieridae, Papilionidae, Nymphalidae and Satyridae account for nearly 75% of the total number of individuals. This is because these families contain many common and popular species.

Fig3 The total number of butterflies recorded at family level at Shimentai Substation

Considering the number of butterflies by section of the monitoring route (Fig4), Section E ranked first (1,663), followed by Section A (1,238), Section D (882), Section B (749) and Section C (705). It is suggested that Section A and Section B, rather open and disturbed by human activities, are more suitable for larger and commoner species.

Fig4 The number of individuals (abandance) recorded by section at Shimentai substation.

Fig4 The number of individuals (abandance) recorded by section at Shimentai substation

The seasonal occurrence of abundance of butterflies is quite apparent, with the highest number of butterflies recorded in May (838), followed by June (744), July (701), with the lowest in January (90) (refers to Fig5). Due to the recording area located in subtropical region, most of the butterflies occur almost all the year apart from the winter season. So, there are no distinct generation divisions as those in temperate regions, such as in Britain. Except for December to February, butterflies are abundant in number, particularly in the spring and summer seasons.

Fig5 Monthly fluctuation in the number of individuals (abundance) recorded at Shimentai Substation

Fig5 Monthly fluctuation in the number of individuals (abundance) recorded at Shimentai Substation

(2) Butterflies Species

During the monitoring period, 162 species in total of butterflies belonging to 11 families were identified. This figure represents 45.5% of the total species that we recorded in the Reserve in PRO NATURA FUND 2001 (356 spp.). In addition, 8 species were newly recorded from the reserve, i.e., Athyma zeroca, Lethe mekara, Mycalesis panthaka, Ypthima multistriata, Y.tappana, Celaenorrhinus sp. (Fig6, A), Tagiades menaka, Pithaura marsena, P.stramineipennis (Fig6, B). 31 species are the first records for Shimentai Substation. The differences in species number between 2001 and 2002 in the site are summarized in Table1.

Fig6 2 skippers of the 8 newly recorded butterflies in 2002 from Shimentai Natural Reserve. A: Celaenorrhinus sp. B: Pithaura stramineipennis

Fig6 2 skippers of the 8 newly recorded butterflies in 2002 from Shimentai Natural Reserve. A: Celaenorrhinus sp. B: Pithaura stramineipennis

Table1 The number of species recorded in 2001 and 2002 in Shimentai Substation

Table1 The number of species recorded in 2001 and 2002 in Shimentai Substation

Note Data on 2001 (2001.10~2002.09) is from Wang,et al.(2003)

Table1 show that new records of species were added to the families Hesperiide (16), Lycaenidae (22), Nymphalidae (5), Satyridae (4), Riodinidae (3) and Pieridae (1). In contrast, the 3 species in the families Papilionidae, Danaidae and Amathusiidae recorded in 2001 were not confirmed in 2002.

The butterfly species were most rich in Section B (150 spp.), followed by Section D (148 ssp.), C (140 ssp.), E (124 ssp.) and by section A (118 ssp.) (Fig7).

Fig7 The number of species recorded by section at Shimentai Substation

Fig7 The number of species recorded by section at Shimentai Substation

Comparing between Fig4 and Fig7, it is found that the number of individual and that of species at each section are not correlated in proportion. The number of individuals is rather few in Sections B, C and D (Fig4), while the species numbers in these sections are much higher (Fig7). This is largely due to the environmental differences at each section. Sections A and E are actively used by agriculture, and there were living wastes of human and animals which can be food resources of butterflies, as well as some cultivated food plants of larvae. Sections B, C and D are located within the natural forests with well preserved habitats, and only some forest-living butterflies occur there, such as members of Lycaenidae and Hesperiidae.

Concerning the seasonal occurrence, butterfly species are most rich from April to August; the largest number was recorded in May, while the smallest one in January (Fig8). This correlated with seasonal changes: there were many butterflies in the spring season when many plants were in blossom and new buds and leaves appeared.

Fig8 Monthly fluctuation in the number of species recorded at Shimentai Substation

Fig8 Monthly fluctuation in the number of species recorded at Shimentai Substation

(3) Rarity or Abundance of Butterflies

The 58 species of butterflies existing in UK are divided into common and rare species according to the monitoring result since 1970's. However, such a division is rather difficult for butterflies in Shimentai due to diversified habitats and the large number of butterfly species. Here, we tentatively classify the butterflies into 5 categories according to the numbers of individuals counted during the monitoring period, e.g., Sporadic: 1~10; Rare: 11~30; Common: 31~50; Very common: 51~100; Dominant: more than 100 individuals (Table2).

Table2 Rarity abundance of butterfly species in Shimentai Substation

Sporadic: 1~ 10; Rate: 11~ 30 ; Common: 31~ 50; Very common :51~ 100; Dominant: 100.

Table2 Rarity abundance of butterfly species in Shimentai Substation. Sporadic: 1~ 10; Rate: 11~ 30 ; Common: 31~ 50; Very common :51~ 100; Dominant: 100.

It seems that most species of butterflies belong to rare, common and dominant categories, with sporadic one includes mainly species of the families Lycaenidae and Hesperiidae, while wide spread species belong to Pieridae, Papilionidae, Danaidae and Satyridae.

(4) Factors Affecting Monitoring Results

There are many factors affecting butterflies activities. It seems that one of the most important factors affecting butterfly flight is weather, particularly the temperature.

In general, butterflies do not fly in very cool weather, regardless of sunshine. This is particularly prominent in the family of Papilionidae. However, a very small number of species in the families Pieridae, Satyridae and Lycaenidae can be recorded at low temperature (10℃) in winter. Another important factor is the sunshine, since many butterflies prefer sunny places in forests; excessive sunshine will make butterflies hide under the shade of leaves or rest on the water site.

Rainfall also affects flight of butterflies; very small rain with semi-fine sky seems to be suitable for flight, but butterflies stop their flight in heavy rain with dark sky.

Wind hardly affected the flight of butterflies in the study site except for extremely strong wind which was rarely encountered.

Other factors affecting butterfly counts include food resources of adults and larvae such as nectar flowers and sap, water site such as stream or small pond and hill or open spaces in the forests. As a general rule, sections or route with more diversified habitats will support much more butterflies species in it.

(5) Suggestions for Butterfly Monitoring in Subtropical Region

Monitoring of butterflies is a long-term scheme which can provide unique information as clearly shown by British Butterfly Monitoring Scheme. It is also indicated that a large scale monitoring including many sites at different regions can supply valuable data for comparative study.

In order to promote butterfly monitoring and to improve their conservation in subtropical regions, a kind of school class is needed to train and qualify volunteer recorders who will conduct monitoring at natural reserves, countryside and cities.

As for Shimentai, we will continue the monitoring in collaboration with the staffs of the reserve to gather the data for long term use in S. China.

ACKNOWLEDGEMENTS

We would like to express our sincere thanks to Pro Natura Foundation-Japan & The Nature Conservation Society of Japan for support of the project, and also to Porf. Pang Xiongfei, Mr. Xie Guozhong and the officials and staffs of the Shimentai Natural Reserve for joining and facilitating our monitoring.

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