Page 1 Nat. Hist. BULL. SIAM Soc. 38: 135-161, 1990 ECOLOGY AND
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NAT. NAT. HIST. BUL L. SIAM Soc. 38: 135-161 ,1990 ECOLOGY AND BEHA VIOR OF KITT I' S HOG-NOSED BAT (CRASEONYCTERIS THONGLONGYA 刀IN WESTERN THAILAND Surapon Duangkhae* ABSTRACT The The and ecology behavior of a colony of Craseonycleris Ihonglongyai was studied during during November ,1984 to May , 1986. Craseonycleris was found to have two short foraging periods ,one around dawn and another at dusk. Th e mean duration of activity was 18 min in the moming moming and 30 min in the evening. The bats used specific flyways to reach their foraging areas which which were less than 1km from the cave. The numbers ofbats using each flyway changed daily and and seasonally. The foraging periods of the bats als ら seasonally. varied Craseonycleris appeared appeared very sensitive to changes in environmental conditions; low temperature and heavy rains rains inhibited foraging activity Recommendations Recommendations and guidelines are given conceming minimizing disturbance to the the roosting caves and foraging areas ,future research , and the establishment of a long term population population monitoring program 飢 d an education center. INTRODUCTION Kitti's Kitti's Hog-nosed bat (C ・raseonycteris thonglongy αi) was discovered in 1973 by Kitti Kitti Thonglongya , in a cave near Sai Yok Waterfa l1, Kanchanaburi Province ,westem Thailand Thailand (Figs. 1 and 2). At that time he co l1 ected 52 bats from the cave (THONGLONGY A , 1973). 1973). In the month fo l1 owing discovery ofthe bat ,Kitti Th onglongya explored about 50 more caves caves along the Khwae Noi River (River Khwae) but no more bats were found. On the basis of the unique characteristics of this bat ,J.E. HILL (1 974) described Craseonycteris Craseonycteris thonglongyai as a new species in its own family ,Craseonycteridae. The family has has taxonomic affinities with the Rhinopomatidae and Emballonuridae. Craseonycteris is also also the world's smallest known mammal , with a body mass of only about 2g (HILL , 1974). In In 1980 ,500 km 2 of forest in the Sai Yok area were declared as Sai Yok National Park Park (ROYAL FOREST DEPARTMENT , 1980). Many tourists came to see the world's smallest mamm a1 in Sai Y ok Cave after it was promoted by the park officials. In In 1981 ,J.D. Pyechecked inSai Yokcave with an ultrasonic batdetector(PYE ,1981) , but but found only one Craseonycteris. However , he found about 200 bats of this species in Wang Phra Phra Cave ,outside the park (Fig. 2). In November 1981 , R. Stebbings and M.D. Tuttle found that that the bat had disappeared from Sai Yok Cave and that only 50 bats ,instead of the 200 申 W iI dlife Fund τbailand ,251/88-90 Phaholyothin Road ,Bangkhen ,Bangkok 10220 ,Thailand 135 135 136 SURAPON 0 UANGKHAE BURMA 20 18 THAILAND 14 KAMPUCHEA SEA GULF OF 10 THAILAND 8 0 !10 lOO Km . 1......-1.-...J 6 98 10 Figure I. A, Sai Yok National Park in western Thailand. B, Study site at cave 30. ECOLOGY AND BEHA VIOR OF KITII'S HOG-NOSED BAT 137 -· ............ 0 2 4 6 8 '"- Km. \ • -·-·-SAl YOK PARK '· ........ BOUNDARY '· \ \. 8 - KHWAE NOI RIVER o' (RIVER KHWAE) ·'-·--~c A . BURMA"-. \. Figure 2. Map showing: A, Sai Yok Nati onal Park ; B, Sai Yok cave: C, Wang Pra cave: D, Study site in dry evergreen fo rest at cave I. 138 138 SURAPON DUANGKHAE previously previously estimated by Py e,still remained at Wang Phra Cave (S 百 BB 削 GS & TU 1TL E ,1982). In In January 1982 ,J. A. T. Hall found no bats at Sai Yok cave and confirmed the count of 50 Craseonycteris Craseonycteris at Wang Phra cave. Two new Craseonycteris caves were discovered by Hall , one outside the eastem boundary of the p釘'k, and another in the southem p創 1 of the park (HALL , 1982). The objectives of my study were to (1) establish the activity cycle ,foraging pattem and home range of Craseonycter;s in selected study caves; 佃 d (2) examine the effects of environmental environmental conditions (air temperature ,relative humidity and light intensity) on foraging behavior. behavior. This study ofbehavior and ecology was undertaken to evaluate and perhaps improve the the bat's chances for survival in the face of frequent human disturbance. STUDY AREA The site selected is in the dry deciduous forest in Sai Yok Dis 佐ict , Kanchanaburi Province ,westem Th ailand , about 10 km east of the town of Sai Yok (Fig. 3). The cave ('cave 30') 30') is located in a hill at 240 m elevation at 99 ・13.9'E ,14 ・7. 7' N. It has two entrances: one used used by Hipposideros bicolor and another by C・raseonycteris. The area around the cave is rocky rocky with clay soi l. Primary forest is found on the hill , but the remaining forest on the slope is is secondary grow 出 with grasses (Figs.4 and 5). Th e canopy was dominated by Shorea siamensis siamensis Miq. Other species present included Bridelia retusa Spreng. ,Terminalia chebula Retz. ,Xylia 巧Ilocarpa Taub.var. kerrii (Craib) Niels. , Careya sphaerica Roxb. , Eugenia cumini cumini Druce ,Dalbergia cultrata Grah. ex Benth. ,La nna coromande /i ca Me 汀. and Schleichera Schleichera oleosa Merr. Th e understorey and c卸 opy were open enough to allow direct observation observation of Craseonycteris activity. settlers Human settlers have invaded the forest on the hill since 1983. The villagers were clearing clearing the forest for charcoal , leaving behind only grasses and shrubs. Some additional observations observations of foraging behavior were made at cave 1 at the edge of Sai Yok National park , ne 紅 dry evergreen forest (map ,Fig. 2). Climate Climate at the study site Westem Th ailand has three se 儲 ons. Monthly changes in temperature , humidity and rainfall rainfall are shown in Fig. 6. Winter Winter begins in late November and ends in early February. Most of the days are sunny sunny and cloudless. Rain falls occasionally lasting one or two days ,卸d then the weather becomes cooler. Dew and mist 釘 e heavy in early moming and evening. During the study 血e average average minimum temperature and humidity in the moming were 18 ・C and 82% ,respectively (n=28 (n=28 days). Summer begins in late February and ends in late Apri l. Most days are cloudless and become very hot 叩 d dry in the aftemoon. During the study the average maximum temperature in in the aftemoon was 40 ・C; the relative humidity was 35% (n=28). Th e difference between moming and evening temperatures was about 15 ・C. Th e rainy season extends from late April to early November. Most days are cloudy , and rain falls almost every day ,usually in the aftemoon. Storms bring heavy rain for a week or or more in September and October. Average maximum temperature during the rainy season ECOLOOY AND BEHAYIOR OF KITT!'S HOG-NOSED BAT 139 24 25 Figure 3. St ud y s ite at cave 30. A.B.C.D = fl yways: CP =check-poi nt 125 m from cave entrance. Map redrawn from I : 50.000 sheet 4837 Ill . Amphoe Sai Yok. edi ti on 2- RTSD. Numbe red grid li nes are I km apart. 140 140 SUR APON DUANGKHA E Fi gur e 4. Forest near cave 30 in summ er (dr y season). Fi g ure S. For es t near cave 30 in rain y se aso n ECOLOGY AND BEHAYIOR OF KITTI'S HOG-NOSED BAT 141 ,....---- ,_ 2!50 ~ ~ ~ 20 o- r--- E E .....1 <J. 1!50 - LL.. I-- z Cl Q: 1001- r-- 9 0- ~ 1--- 1 1-=---1 ............... ----&.. ... _ 90 :::0 ~--_.....--_....- .......... ['1'1 ... _______ ........... - ..... ~ - mox. RH'"' r u 40 --- -- ......... eo ~ !... < w 3!5 mox. T 70 rn 0:: ___ __ .. ::z::: :::> 1- 30 60 c <t ' ..· --.....-- ...... -min.- RH ' ',..._ ~ Q: 0 w 25 ' 50 0.. in.T ' ' -i :E • -< w 20 40 1- -~ 15 30 J F M AP M JU JL AU s 0 N D Figure 6. Above: Average monthly rainfa ll (Royal Irrigation Dept. , Lum Sum station, Sai Yok, 197 1- 1980). Below: Average maximum and minimum monthly temperature and relati ve humidity (Royal Meteorological Dept. , Kanchanaburi Station, 197 1- 1980). 142 142 SURAPON DUANGKHAE was 30 ・C. 百le maximum temperature in the aftemoon was about 5・C higher than the minimum temperature in the moming. During the day the average relative humidity was 90% (n=28). (n=28). METHODS Trail Trail cu 師'ng and transects to jind loraging area Transect Transect trails 500 m. in length were cut around the cave (Fig.3) in order to patrol about about the cave to detect foraging activity. After the general daily pattem of activity was determined 出ese trails were walked wi 曲 a bat detector s刷 ing just before 曲.e bats began emerging emerging from the cave. Any Craseonycteris sound detected along the trail was marked on 由emap. Checkpoints Checkpoints were selected to observe C l' aseonycteris activity and record environ- mental mental conditions. A point on a Craseonycte l' is 唱 yway" at 125 m from the cave was selected as as a checkpoint (Fig. 3). Data from the 125 m checkpoint were recorded in 1986 ,on 28 days over over three seasons , as follows: 12 days in winter: Jan.20 ー27 and Feb. 4- 7; 7 days in summer: Feb. Feb. 19- 20 and March.ι8 and 27-28; 叩 d9 days in 白e rainy season: April 24 and May 14 ー20 and 27. Recording Recording environmental cond 剖ons Air Air temperature ("C), relative humidity (%) and light intensity were recorded during the the active period of C l' aseonycteris.