(Schlegel and Müller, 1844)
Asian forest tortoise
Recognition
This tortoise is the largest in Asia. Its oval carapace (to 60 cm) is domed with descending sides; however, it may be somewhat flattened across the 2nd and 3rd vertebrals. There is little indentation in the cervical region; instead both the anterior and posterior marginals are upturned and slightly serrated. A rather broad cervical scute is present. Vertebrals are wider than long; the 5th is expanded. Well-defined growth annuli surround the flat areolae of the vertebrals and pleurals. Eleven marginals lie on each side, and the supracaudals are divided both dorsally and ventrally. The carapace varies from olive or brown to black; vertebral and pleural areolae may be tan in young individuals. The plastron is well-developed and has both an anterior and a posterior notch. Plastral lobes are almost equal in length and width. The plastral formula is: abd > hum > gul >< fem > an > pect; the pectoral scutes may or may not extend to the midseam. The gulars are thickened and extend beyond the carapacial rim. The bridge is wide; the two or more inguinal scales are larger than the single axillary. The plastron of adults is dark gray, brownish or black, depending on the subspecies; that of the hatchling and juvenile is yellow with black shading, usually around the periphery. The head is moderate to large with a nonprojecting snout and a slightly hooked upper jaw. Its prefrontal is divided longitudinally, and followed by a single large frontal scale; other head scales are small. The head is black with some pink, bronze, or brown pigment. Limbs and tail are black. The anterior surface of each forelimb is covered with large, pointed, overlapping scales. Several very large pointed tubercles (spurs) occur on each thigh, giving rise to the colloquial name of "six-footed" tortoise. The tail ends in a horny scale.
While some males have longer, thicker tails and more concave plastra than females, others do not show these characters. In practice, adults can only be sexed with confidence if they show themselves to possess a penis or lay eggs.
Distribution
Manouria emys ranges from the states of Assam, Meghalaya, and Nagaland in northeastern India, and Myanmar southward through Thailand and Malaysia to Sumatra and Borneo,
Geographic Variation
Manouria emys emys (Schlegel and Müller, 1844), the brown tortoise, ranges from southern Thailand (Ranong, and Nakorn Si Thammarat provinces) through Malaysia to Sumatra and Borneo. It has a domed brown carapace (to 48 cm), with lighter vertebral and pleural areolae; the pectorals are widely separated. M. e. phayrei (Blyth, 1853), the Burmese black tortoise, occurs in Assam, Myanmar, and from Tak Province in northern Thailand to Kanchanaburi Province in the central region. It is almost totally black with a domed carapace which may reach 60 cm, and its pectorals meet at the midline of the plastron. Some M. e. phayrei are proportionally narrower (more elongated) than M. e. emys when viewed from above. Both subspecies may develop more flattened carapaces in captivity due to dietary deficiencies. Nutphand (1979) was apparently unaware of Blyth's earlier description and attributed the name Geochelone nutapundi Reimann to this race.
According to Peter Paul van Dijk (pers. comm.), a wide zone of intergradation between the two subspecies occurs in Thailand from Phattalung Province to Surat Thani Province. Bhupathy (1994) reported finding Indian tortoises with the pectoral characters of both subspecies, and questioned the validity of the current subspecies designations, and Anderson (in Das, 1991) thought that subspecies distinction breaks down in the northwestern portion of the range.
Habitat
This is another highland monsoon forest dweller. It lives in tropical evergreen woodlands, and prefers moist situations. It sometimes forages in shallow mountain streams (Nutphand, 1979). Much time is spent burrowed into moist soil or under leaf litter.
Natural History
A pair of Manouria emys (subspecies not given) first bred at the Wassenaar Zoo, Netherlands when the female weighed 26 kg and the male 16 kg (Louwman, 1982). Mating always began in February and March while the tortoises were still in winter quarters. Mating occurred when the female responded to the male's approach by raising herself, enabling him to mount and place his tail in position under hers. The male emitted loud exhalations of air from his open mouth. The first nest excavation was seen on 1 July, but on two following years, nesting took place on 4 June. A new nest site was chosen each year, and excavation started either in the early morning or late afternoon. Nest cavities were approximately 20 cm deep, and were dug entirely with the hindfeet. After ovipositing and positioning the eggs with the hind feet, the clutch was entirely covered with soil by the hindfeet. Having filled the nest cavity, the female next raked with her forelimbs sand, leaves, and grass into a heap over the nest site. This work continued for 3-4 days, with only short periods of rest until a sizable mound was formed (some extra leaves and twigs were supplied). When an Aldabra tortoise approached the mound, the female rose high on all four feet and vigorously rammed the other tortoise. For 2-3 weeks afterwards she remained near the mound, occasionally raking in more material. When she finally left the vicinity of the mound, it measured about 2.5 m in diameter and 20 cm high. The three clutches consisted of 39-42 smooth, white, slightly elliptical (50-62 x 48-55 mm) eggs, which were artificially incubated and began hatching in 66-71 days. Hatchlings had carapace lengths of 51-55 mm, and were dull brown, with spiny borders to their carapaces, and a brown caruncle on their snouts. Within a few days male hatchlings could be distinguished by their slightly longer tails.
McKeown et al. (1982, 1991) reported observations of reproduction of Manouria emys phayrei at the Honolulu Zoo. Courtship of Manouria emys phayrei is generally simplified. A male fixates on a female by fully extending his head and neck forward and pointing directly towards the female, adjusting the position of his head as she moves. The male then resorts to trailing the female around the enclosure. Once up to her, the male utilizes shell ramming to immobilize the female prior to mounting. If the female continues to walk, he bites her forelimbs, and, if this does not stop her, bites at her face. If she stops and withdraws her head into her shell, he extends his neck and forces his head between her withdrawn forelegs and continues to bite her face. Male head bobbing during courtship and vocalizations while mounted also occur. During face to face head bobbing, the male emits low frequency, modulated "moans" of relatively long duration (10-15 s). The female may also vocalize at this time, only the sounds she makes are more infrequent, of shorter duration, and of somewhat greater frequency modulation. Observed nesting behavior was similar to that reported by Louwman (1982). The female constructs a large leaf-litter mound by "back sweeping" ground litter for up to 10 m from the nest site, gradually moving backward to drag materials to the nest mound. A bowl-shape depression is then created in the vegetation mound with the hindfeet, and the eggs are laid in it (females observed nesting by McKeown et al., 1982, 1991, did not excavate a hole in the soil as did those watched by Louwman, 1982). Upon completion of oviposition, the female uses her hindlimbs to gently cover the eggs with a shallow layer of soil creating a smaller mound within the mound of vegetation. She next moves out of the vegetation mound covers it with more vegetation by back sweeping with her front legs until the mound eventually reached 30 cm high. She guards the nest for 3-20 days.
Clutches laid in these nests at the Honolulu Zoo contained 3-51 eggs (larger than that reported for other tortoises; Nutphand, 1979, reported the clutch size for M. e. emys to be 5-8); nesting occurred in April-June and August-October. The brittle-shelled eggs were 49.9 to 72.0 mm in diameter. Hatchlings were 60-66 mm.
Breeding data on wild Manouria emys emys on Borneo was reported by Lambert and Howes (1994). A radiotagged 44 cm female mated with two different males; with a 36 cm male on 6-9 March, and a 33.8 cm male on 16 April. Mating behavior was similar to that reported by Louwman (1982) and McKeown et al. (1982, 1991). Nesting was observed on 7 March, with the female digging with her forelimbs in the leaves and soil between the buttresses of a huge tree, apparently constructing a vegetation mound.
Foods eaten by M. emys include largely aquatic plants, such as tubers and lotus, invertebrates and frogs (Nutphand, 1979; Das, 1991, 1995), and Lambert and Howes (1994) noted that fungi were an important seasonally abundant food source in Borneo. Captive adults at the Wassenaar Zoo ate a wide variety of fruits and vegetables; a multivitamin/mineral preparation was added to the plant foods, as occasionally also were minced meat and one-day-old chicks. The juvenile diet was basically like that of adults, a daily offering of diced fruits and vegetables, but all young showed a marked preference for chopped raw beef when it was offered.
IUCN Red List Status (1996)
Vulnerable (A1cd).