For tortoise, terrapin and turtle care and conservation
Sidney W. Bailey.
Horsfield's tortoise, Agrionemys horsfieldi (Gray), variously known as the Afghan, Baluchstan, Steppe, Four-toed, and Russian tortoise, also has a strong British connection, having been named by the herpetologist and systematist J.E. Gray, in 1844, after the nineteenth century naturalist and traveller Dr. Horsfield, who first recognised it as a separate species.
From that time until 1980, this tortoise was included within the genus Testudo, but since that date it has been placed, as a single species in the genus Agrionemys.
Description:
This tortoise is comparable in size to Testudo hermanni, having a carapace length of between 13 to 20 cm, with females growing to a larger size, than the males; however, the record size is given for a specimen in a Russian Museum, with a carapace length of 28.6 cm ( nearly 1 ft), while the greatest weight is given as kg for a living specimen.
The shape of the shell is rounded, and wider than long in young specimens, becoming more ovate in adults, the top being moderately depressed, with no suggestion of the edges of the carapace being reverted or turned up. The marginals meet the bridges in a continuous manner.
Some specimens exhibit a totally light sandy coloration to the shell, but usually there are variable amounts of black pigmentation present on the carapace, while the shields of the plastron are often totally black in colour. The colour of the skin varies from light tan to dark gray, according to age. The upper jaw is tricuspidly notched anteriorly, while the lower jaw has a single cusp. The vertebral and costal plates are wider than long. This species has both the thigh spurs as found in Testudo graeca and the tail nail as found in Testudo hermanni, but these two features are less pronounced in Agrionemys horsfieldi.
The main feature of identification is the presence of only four claws on both the front and back feet whereas T. graeca and T. hermanni have five claws on the front feet and four on the hind feet.
Geographical Distribution
Two-thirds of the entire range of Agrionemys horsfieldi, lie within Asia, while the remaining third partly enters European Russia, therefore it can be considered a predominantly Asiatic species.
Its range extends North Westwards from Baluchistan in Pakistan and into the South Eastern region of Iran, East of Dasht-E-Lut and then through Afghanistan, into Turkmenistan, Uzbekistan and Kazakhstan, in the U.S.S.R, where it has been reported as far North as 52 degrees 30' , which is the most northernly record for any species of tortoise. However this was for one isolated specimen only, which was most probably a released captive tortoise.
It must be appreciated that over this extremely wide range, the habits of this tortoise would vary considerably from north to south, particularly in regards to hibernation and aestivation. The only areas where detailed observations have been made in the field, come from within the U.S.S.R. The material cited has been collected from a variety of sources which are given in the references, some of which may not be readily available in this country-
Habitat and Life Cycle
The type of terrain inhabited by this tortoise East of the Caspian Sea and West of Lake Balkhash, from the Turanian Plain in the South to the Kirghiz Steppe in the North, is comprised of black sand desert, semi arid desert and seasonal grassland steppe, characterised by outcrops of limestone rock.
The tortoises are found in lowland valleys, on the slopes of hillsides, and on rocky plateaus with a gradient of up to 70 degrees and at an altitude of up to 2300 metres above sea level. They are said to avoid the salt pan areas of the Caspian Depression, preferring loamy slightly saline soil covered with a seasonal overgrowth of Astragalus sp vegetation.
This species has much in common with the North American tortoises belonging to the genus Gopherus, following the same behavioral pattern by constructing burrows in the ground, which serve both as night retreats and for longer periods of aestivation and hibernation. The burrows of Agrionemys horsfieldi, are on average not more than 2 metres in length, and between 20-5Ocm in depth and are usually made into the banks of hillsides or rising ground to avoid flooding during wet weather. Alternatively they may take over neglected burrows made by the European Marmot or the Long-Eared hedgehog.
The life cycle of Horsfield's tortoise, is entirely governed and linked to the ecosystem of the region in which it lives, being dependent on the seasonal overgrowth as a source of food supply. This covering of vegetation begins to grow early in this area, towards the end of February and it has been reported that tortoises have been seen emerging from their burrows by the 28th of February, when the temperature was between 20-25°C. The mass emergence, however, is said to take place about the middle of March, with the males appearing first, to be followed by the females towards the end of March; by this time the temperatures in early April can reach 30-33°C in the afternoon. "The tortoises were active from 6.15 am to 12 noon, they then sought shelter within their burrows, or amongst vegetation until 1 6.00 hrs when they recommenced their activities, finally retiring for the night at about 19.00 hrs. The optimal temperature for this species is probably between 18 and 27°C' (Sammakov 1966). Mating occurs from the beginning of April until the middle of May. Males are said to be mature at 11 to 12 years, and the females at 13 to 14 years (Brusko 1978). The eggs are said to be 44 to 55mm in length and 26 to 36mm in breadth, and are deposited in shallow holes dug to a depth of about 7cm, being from 3 to 7 in number. The incubation period is from 75 to 82 days, according to the prevailing weather conditions.
Population density was studied in one region of Alma-Ata, from 12 April to 4 May, over a site of 3 hectares, using a liner march of strips 10 metres wide; a population of some 1,359 tortoises was estimated by marking in this area (Broesjko 1976). By the end of June and the beginning of July, the majority of these tortoises had disappeared into their burrows for their summer period of aestivation, which lasts until the end of September and the beginning of October; this is because the vegetation has withered and dried and the earth parched dry by the heat of the summer sun. During the autumn rainfall, the plant life returns for a short period which brings the tortoises out to feed for a few weeks, but by the end of October and the beginning of November, the tortoises return to their burrows for their winter hibernation. It is reported that the entrances are sealed with a plug of earth some 20cm thick Temperatures can fall drastically in these areas to well below freezing for prolonged periods but the tortoises are said to be able to withstand temperatues of minus 6.7°C. Some 84 different plant species have been listed in the. diet of Agrionemys horsfieldi, they include the following, Astragalus paucijugus, Convolvulus arvensis, Dodartia orientalis, Iris kopetdaghenis, Bromus tectorum, Leontice eversmanni, Allium sabulosum, Medicago sativa, Papaver pavonium, Merender robusta, Scorzoner pusilta, Tetracme recurvata, and many of the vegetables and fruits found on cultivated fields.
It is at this point that tortoises fall foul of man.
At an ever increasing rate, close to the settlements and villages, large areas of land have been brought under cultivation, the growing season being extended by crop irrigation. The tortoises are attracted towards these oases, as sources of abundant food supplies, whereupon the farmers employ contractors to rid their land of what they consider to be vermin. In this way many thousands of tortoises are systematically destroyed. The method of disposing of the tortoises is economically ingenious; they are loaded into mechanical pulverizers, and the resulting product is then fed to mink and other animals on fur producing farms, or used as bonemeal for fertilisers. This practice could eventually lead to the depletion, and possible extermination of the tortoises in these farmed areas, but the total range of this species outside of the cultivated areas is so great, that it in no way endangers the species as a whole-
They appear to have few natural enemies- The Steppe fox is said to take juveniles in its diet, while adults are sometimes attacked by birds of prey such as the Golden eagle, the Bearded vulture, the Black Kite, the Eagle owl, and the Raven (Rustamov 1958, Suchinin 1971 ).
Discussion
Surprisingly, a number of Russian authors have expressed the opinion, that the life expectancy of Horsfield's tortoise is on average between 23 and 25 years, about 21 for males, and 25 for females, with some females reaching 30 years, but this is much shorter than the life span usually given for similar species of tortoise. Only one author gives the method of assessment for this figure, which was arrived at by counting the growth rings on the shields. While it may be possible to estimate the age of a tortoise for the first ten to fifteen years of life by this method, after this time the rings begin to run together and become obscure and worn, particularly in the case of a burrowing species, making this method notoriously unreliable.
Another surprising opinion expressed, is that most of the tortoises, on entering their burrows in July, remain in a parabiotic state for a period of eight months, their summer aestivation turning into winter hibernation, leaving a incredibly short period of four months in which to prepare for this severe regime (Ataev 1975).
Some British authors have expressed the opinion that the Horsfield's tortoise would be the ideal species for keeping outdoors in Britain, but while it is true that it is very hardy and can tolerate lower temperatures than either T. hermanni, or T. graeca it is no more suitable for outdoor conditions in this country, than are these two species. Britain with its maritime climate, gives moist temperate summers and mostly wet, cool winters, and this is far removed from the climatic conditions experienced by Horsfield's tortoise in any part of its range.
While they certainly would not have any desire to aestivate in this country, some owners report that they have difficulties in inducing them to hibernate successfully. One owner in Sweden, resorts to placing them in a refrigerator (Sjokvist 1982). Considering that they would not hibernate at the southern end of their range (Pakistan) it would appear possible, that if maintained with a plentiful supply of food at a temperature of about 23.9°C, they would remain active throughout the year. It is always an advantage to supply a deep layer of loose substrate, to facilitate their burrowing propensities, having observed specimens confined to back gardens with hard earth and concrete paths, to have badly worn down front claws and toes.
In common with the Mediterranean tortoises, mass importation of A. horsfieldi is now banned in this country. The last large importation here, occurred between 1965 and 1971 , with a figure of 119,319 tortoises given.
It would be interesting to learn how many and for how long these arrivals survived in this country. I have only been able to locate a few from this period, one such animal having lived in Surrey for the past seventeen years, being fully grown when first acquired and which is kept in a combination of outdoor and indoor accommodation.
This particular specimen emerges from a short period of hibernation in the last week of February, conforming with Ataev' s date of emergence, February 28th.
As in one or two other cases, I found that the owners were unaware of the true identity of their pet and probably for a large number of people who purchased a "Tortoise for the Garden" at that time, a tortoise is a tortoise, the precise identity of the species often being unknown to them.
Comment
While no one wishes to see the return of the mass importation of tortoises into this country, it does indeed appear ironical, when large numbers of this species are being systematically destroyed in certain areas, that legislation makes it difficult for even a limited number of these tortoises to be allowed into this country for genuinely interested people and herpetologists to keep and study.
REFERENCES
Langerwerf, B. ( 1 979). Materialen over de vermenigvuldiging van Centraal.Aziatische schildpadden in het gebied ten zuiden van het Balchasjmeer. De Schilpad 1979 No. 4.
Note: Much of the information and references to Russian work came from this source which was a translation into Dutch from the Russian article by Z.K. Broesjko, Institute of Zoology, Alma Ata, Kazachstan, U.S.S.R originally published in Herpetologisch Verzamelde Werken, Leningrad (1976).
Pritchard, P.C.H. (1979). Enclyclopaedia of turtles. T F H. Publications, New Jersey. R.S.P.C.A. ( 1979). The tortoise trade. RS.P CA., Horsham, Sussex
Testudo Volume Two Number Four 1986