Scientific name: Testudo (Agrionemys) horsfieldii
Common names: Horsfield's Tortoise, Russian Tortoise, Steppe Tortoise, Afghan Tortoise, Central Asian Tortoise, Four-toed Tortoise
Subspecies: Three currently recognised subspecies: T.h.kazachstanica, T.h.rustamovi, and T.h.horsfieldii (1) (but see 2)
Identification: Horsfield's tortoise is of small to medium size, with a maximum carapace length of about 30cm. It is easy to distinguish from all other Testudo tortoises as it lacks a plastral hinge, and only has four claws on the front feet rather than the customary five. It also has a relatively flat and rounded carapace.
Range: The range of Horsfield's tortoise encompasses eastern Iran, Afghanistan, Turkmenistan, Uzbekistan, Tajikistan, Kyrgyzstan, southern Kazakhstan, the westernmost part of Xinjiang (China), and part of northwestern Pakistan (references in 2). It's range has been reported to cover 3,362,935 km2, with the Central Asian deserts containing 73% of the species range (3).
Habitat and it's consequences:
Horsfield's Tortoise is a widespread and abundant species yet it inhabits inhospitable environments such as desert, semi-desert and steppe habitats. It can also be found in foothills, mountains, marshes, valleys, and floodplains (4,5). Due to unfavourable conditions for most of the year, it is only active in Spring, and Individual tortoises are active for just two months of the year (6). Even during this period, temperatures at night drop as low as -10 °C and daytime temperatures reach 45°C (6). Tortoises deal with dramatic changes in temperature by burrowing into the sandy soil. During hibernation and aestivation they also stay in these burrows, which can be up to 2m long (7). They are strictly diurnal, yet they are only active when temperatures are neither too cold nor too hot. Incredibly, this means that individual Horsfield's tortoises are active for just 3.5% of the year and spend less than twenty hours a year foraging (6,8).
Reproduction:During their short active period both males and females must acquire enough resources to reproduce and see them through a nine month period of inactivity. Despite intensive activity in searching for mates, males manage to put on weight during the mating season. However, costs of reproduction are higher for females: In a single season they can lay up to nine eggs, spread over three clutches. Eggs are produced from both stored resources (capital) and those acquired in the current season (income) (9). As a consequence, although females spend a greater amount of time foraging than males, their body condition may decrease during the active period (10). It is therefore likely that successful reproduction in a given year will decrease reproductive output in the following year.
Horsfield's tortoises reach sexual maturity from 11-14 years of age, and are fully grown after 20 or 30 years. They start searching for mates immediately after emergence from hibernation in March or April and lay clutches of up to 6 eggs in May. Up to three additional clutches can subsequently be laid in the same season (4).
As with other Testudo species, Horsfield's tortoise is strictly vegetarian, feeding on annual plants whose growing season, broadly speaking, matches the tortoise's active period. Although it has been suggested that Horsfield's tortoise competes with domestic animals for forage, Lagarde et al (8) showed that there is little, if any, overlap in diet between tortoises and livestock: Horsfield's tortoise actively avoids grasses and mainly feeds on plants that can be highly toxic to mammals.
Population size and density:
Population densities of this species vary greatly depending on habitat (11,12). In some places, densities of three or four tortoises per metre have been found (13), whilst in others the density is as low as 0.1 per hectare (14). Mitropolski and Kashkarov (15) estimate an average of 1.13 individuals per hectare, whilst Bondarenko and Peregontsev (14) estimate an average of between five and twenty individuals per hectare. As population density is so variable, estimates of population size are difficult to attain. However, several papers report estimates of about 20 million individuals in Uzbekistan (13,15,16).
Threat Status: Testudo horsfieldii is currently listed as vulnerable by the International Union for Conservation of Nature (IUCN): it faces a high risk of extinction in the wild in the medium-term future. This classification was made on the basis that the Horsfield's tortoise population is projected to suffer a reduction of at least 80% within the next three generations due to exploitation (17). [Note: this classification was made under version 2.3 and is due to be updated].
Threats: Horsfield's tortoises face threats from many quarters. In addition to collection for the pet trade, they also feature in the food market and have been known to be used in traditional Chinese medicine (18,19). Both legal and illegal trade occurs and collection can be so extreme as to eliminate tortoises from large areas (20). On top of this they are threatened by habitat loss due to agricultural intensification (7,19) and war refugee zones (4), and face injury and mortality during desert development, from farm machines, and on roads (19,21). As a result of these factors, both the range and population size of Horsfield's tortoise are in decline (16,19,21).
During the 1960s, Horsfield's tortoise was not imported to the same extent as Hermann's and spur-thighed tortoises, though thousands were still imported to the UK each year. It's lower popularity may be due to various factors, such as restricted trade between the UK and countries within the Horsfield's range, or preference for the look of the latter two.
However, with the lifting of the iron curtain in 1991 and it's new position as the garden tortoise with the fewest trade restrictions, Horsfields tortoise has become the most heavily traded Testudo species in the UK.
Because of high mortality during transport and acclimation of commercial specimens, a ban on imports of wild specimens was imposed in 1999 (September 1999, European Union (EU) wildlife trade regulation 338/97). However, this ban was lifted in 2006 (18). Testudo horsfieldii can again be traded in large numbers, though exporting countries have quotas for both wild and ranched specimens.
Horsfield's tortoise is the only garden tortoise that is now traded in the UK to a greater degree than it was during the 1960s and 1970s. However, level of trade is still less than a tenth of that seen for the spur-thighed tortoise during that period.