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Issue:ISSN 1000-7083
          CN 51-1193/Q
Director:Sichuan Association for Science and Technology
Sponsored by:Sichuan Society of Zoologists; Chengdu Giant Panda Breeding Research Foundation; Sichuan Association of Wildlife Conservation; Sichuan University
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Your Position :Home->Past Journals Catalog->1998 Vol.17 No.2

Studies on Ecology of Testudo horsfieldii Gray and Status of Its Conservation
Author of the article:SHI Hai-tao
Author's Workplace:(Department of Biology, Hainan Teacher’s College, Haikou, 571158)
Key Words:Testudo horsfieldii; seasonal activity; daily activity; type of habitat; population density; conservation
During 1991 and 1992, ecological observations of Central Asian tortoise, Testudo horsfieldii Gray, in the wild were carried out in Huocheng Nature Reserve, Huocheng County, Xinjiang Uygur Autonomous Region. Huocheng County is the only distribution area found in China. This paper summarized the results of the studies.
1.    Study Area and Methods: The study area lied in 80º42.75´-81º4.6´E, 44º3.5´-44º17´N. The Central Asian tortoise lived in the arid environment from 650 to 1100m above sea level, the average temperature was 9.34, rainfall was 220mm, the dominant vegetations in this region was the compound of ephemerophytelamb s- quarsdters-artimisa.
The highest density area of tortoise- Kathmandu was selected as the long-term study area. More than fifty tortoises collected from the wild were put into a pen of 2000m2 area in the habitat of T. horsfieldii, the pen was digged with a border of 30cm depth prevented tortoises from running away. The body temperature of 5-10 tortoises, substrate temperature, air temperature and illumination strength were written down every hours in active period of tortoises. The habitat selection and vegetation were surveyed with sample method. Food habit and reproductive behavior were obtained with field tracking, captive observation and raising methods, the population density was censused with line transect method.
2.    Activity Rhythm: The activity rhythm of T. horsfieldii was studied from April 1991 to April 1992. Between the end of March and the early April, the tortoises ended dormancy and enter active stage. In the early April, the lower ambient temperature and levels of solar radiation produced a unimodal activity pattern, and higher proportion of tortoises basked from the morning to the evening. From mid April to mid August, high environment temperatures and levels of solar radiation produced bimodal activity pattern. From mid April to mid May, suitable environment temperature produced the best exuberant activity, the frequency of both feeding and mating reached peak. But from mid May to mid August, with the continuously raised environment temperature, the duration of prevent sunstroke was prolonged and the active time was shorten comparatively. By the end of June, a part of tortoises began to aestivated, up to 20 July, 87% tortoises had aestivated, up to 25 August, all 46 tortoises in the pen had aestivated. Ten dormancy holes were measured during April 1992, the average total length of dormancy hole was 179±25cm, the average vertical depth was 122.2±17.5cm, the average horizontal length was 130±30.5cm.
The daily activity of T. horsfieldii may be divided into five periods: turn around, sun-basking, forenoon activity, prevent sunstroke and afternoon activity period. The body temperature of turn around period of tortoises was markable difference in different season. Turn around behavior was irrelevant to body temperature, and only relevant to biorhythm. From April to August, with the environment temperature raised continuously, the time of sun basking tended to be shorten. In different season, the body temperature of ending sun-basking and beginning forenoon activity was average 28±2.1. When the body temperature reached 35.1±0.8. the tortoises ended forenoon activity period and digged into hole so as to prevent sunstroke. After 18:00 – 19:00 hours, when the substratum temperature was under 40, the tortoises entered afternoon activity period, when the illumination was under 3.2±0.5 ten thousand Lux, the tortoise ended daytime activity. 1650 body temperature data of tortoises were analysed, the mean lower limit and upper limit body temperature of activity was 28±2.1 and 35.3±0.58 respectively in natural condition, the optimum range of body temperature was between 31 and 34, the optimum body temperature was 32.4±1.
3.    Habitat and Food habit: The habitat of T. horsfieldii can be divided into four types: northern slope of hills, southern slope of hills, valley floor, and hill top. The tortoise occurred mainly in southern slope and valley floor in earlier spring, and in valley floor in summer and autumn. The food of T. horsfieldii consisted of 47 plant species which were more than 80% the total species of plants in the Nature Reserve, 18 of which e.g. Astragalus spp, Convolvulus spp. And Galium apraive etc. were taken most frequently. The daily capacity for eating of subadults was 4.1±1.8g/d(n=6), and that of adults was 9.7±7.3g/d(n=8). The daily time for eating of subadults was 10.3±3.4min./d, and that of adults was 27.8±21.5min./d.
4.    Reproduction: The mature females laid gees during May. Among ten mature females, only two laid eggs at 12 and 14 May respectively, their clutch size were 3. The process of nest building, egg-laying and nest burying needed about 90, 5 and 5 minutes respectively. Among six hatched eggs, only one hatchling emerged in 10September, the incubation lasts 120 days, two hatchlings died in eggs, one egg was broken, the other two were unfertilized eggs, so the hatching rate was 16.7%.
5.    Population Density and Conservation: From 1957-1992, the population density census of T. horsfieldii was carried out with line transect method in Huocheng, Xinjiang. The results as follow: the distribution area and population density of T. horsfieldii were respectively 500km2 and 4136±2162 ind./km2 in the earlier 1960s; 270km2 and 61.5±31 ind./km2 in the earlier 1980s; 180km2 and 6.04 ind./km2 in the earlier 1990s. A total of 77 tortoises found in 1991-1992 were analysed, among which 37 were males, 37 females and 3 hatchlings, the sex ratios was 1:1. The age of 31.2% were 12-15 years, 28.6% were 9-12 years. Females had significantly greater body mass and longer carapace than males.
The body mass of 27.3% tortoises was 300-400g, 28.6% 400-600g. The carapace length of 77.9% tortoises was 9-15cm.
Now the population of Central Asian tortoise in China is sharply reduced. It is very rare in the wild. If effective measures were not adopted at once, it will be extinct in China soon.
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