Capricornis sumatraensis
Sumatran serow
(Also: serow)

Sumatran serows, Capricornis sumatraensis, are found on the Thai-Malay Peninsula and on the Indonesian island of Sumatra. There are three specific areas of highlands on the island of Sumatra that have been identified as supporting populations of C. sumatraensis: the Barisan mountains in the south, Aceh in the north, and Kerinci in the central part of the island. (Duckworth, et al., 2008; Santiapillai and Ramono, 1994)

Capricornis sumatraensis is found in mountainous areas at altitudes of between 200 and 3,000 m. It resides mainly in forests and is frequently found near cliffs. (Santiapillai and Ramono, 1994)

A close relative, Capricornis milneedwardsi, inhabits areas near the top of steep slopes with high densities of shrubs. (Chen, et al., 2009)

In body shape, Sumatran serows resemble goats or antelopes. They are generally dark grey or black in color with backward pointing horns that narrow at the tips. The horns usually have a slight curve. A skin of C. sumatraensis measured 60 inches (approximately 152.4 cm) from nose to tail. (Pocock, 1908; Santiapillai and Ramono, 1994)

There is no information regarding sexual dimorphism in this species and standard measurements are not available. However, in a close relative, Capricornis crispus, both males and females were reported to weigh between 30 and 45 kg, with horns that averaged 12 to 16 cm in length. (Kishimoto and Kawamichi, 1996; Ochiai and Susaki, 2002)

At approximately 30 kg, Capricornis swinhoei, a close relative native to Taiwan, is slightly smaller than C. sumatraensis. (Wang and Chen, 1981)

The mating system of C. sumatraensis has not been described, but a close relative, Capricornis crispus, commonly forms monogamous pairs. A single pair will often stay together for multiple years, each sex maintaining a territory that overlaps with the territory of its mate. Occasionally, polygynous groups form, but since females maintain their own individual territories, it is difficult for the male to guard multiple females. A typical pair bond lasts approximately 4.6 years. (Kishimoto and Kawamichi, 1996; Ochiai and Susaki, 2002)

The breeding season of C. sumatraensis occurs between the months of October and November. Gestation lasts approximately 7 months and, in one recorded instance of a captive Sumatran serow, birth occurred in early June. Usually the mother gives birth to 1 offspring. (Galstaun and West, 1982)

Little is known about growth and development of young Sumatran serows, but in Capricornis crispus, a close relative with a similar gestation period, young stop being dependent on their mother at about 1 year of age, but stay in their mother's territory for 2 to 4 years. Capricornis crispus females reach sexual maturity at about three years of age. (Kishimoto, 1989; Ochiai and Susaki, 2002)

Parental care in Capricornis sumatraensis has not been described. However, in a close relative, Capricornis crispus, the mother is the sole care provider for her young. Shortly after birth, the serow kid is able to travel with its mother as she forages for food. In C. crispus, a mother and kid will often stay close to the area where the kid was born for the first few days after birth. Capricornis crispus mothers are occasionally observed between the months of May and July without their kid, which suggests that kids sometimes hide for short periods of time. (Kishimoto, 1989)

The maximum lifespan observed in a close relative, Capricornis crispus, is 20 to 21 years for males and 21 to 22 years for females. At birth, females have shorter life expectancies, 4.8 to 5.1 years, compared to males, with life expectancies of 5.3 to 5.5 years. (Ochiai and Susaki, 2002)

Sumatran serows are shy animals. While generally solitary, small groups are occasionally observed. Trails in serow habitat indicate that routes that are used to reach specific areas. Although Sumatran serows spend almost all of their time on land, they are known to be good swimmers as well. (Santiapillai and Ramono, 1994; West, 1979)

Aggressive encounters between Sumatran serows have not been fully described. However, a close relative, Capricornis swinhoei, stomps the ground with both front feet when angered and uses its horns as its primary weapons. Capricornis sumatraensis has been observed to use biting as a last resort, when it is not able to kick with its front legs. (Wang and Chen, 1981; West, 1979)

Capricornis sumatraensis is a territorial species. Individuals mark territory boundaries using dung piles, which are usually placed in areas where they are not disturbed by the elements but are not hidden enough so as to prevent another serow from detecting them and consequently trespassing. (Lovari and Locati, 1994)

There is no information on territory size for Sumatran serows. In Capricornis crispus, males typically occupy larger territories (16.2 ha) than females (10.5 ha). The territories of two individuals sometimes overlap and encounters with an individual of the same sex usually result in aggression. Territory owners typically chase intruders from their territory. (Ochiai and Susaki, 2002)

Observations of C. crispus indicate that kids recognize their mother by sound. (Kishimoto, 1989)

Capricornis sumatraensis has preorbital and interdigital scent glands. These glands are used to mark boundaries of territories. Capricornis swinhoei, a close relative that exhibits behavior very similar to that of C. sumatraensis, produces a high-pitched alarm call. (Wang and Chen, 1981; West, 1979)

Sumatran serows are forest browsers and appear to prefer nutrient-rich vegetation, though they eat nearly any type of vegetation if nothing else is available. Multiple individuals are occasionally found feeding together in areas high in resources. A close relative, Capricornis swinhoei, has been observed in captivity to feed primarily during the evening hours and at night. Another close relative, Capricornis milneedwardsi, eats primarily the leaves and twigs from deciduous broadleaved trees. (Chen, et al., 2009; Santiapillai and Ramono, 1994; Wang and Chen, 1981)

Sumatran serows typically select bedding sites that are protected from the wind, but not secluded enough to allow a predator to sneak up on the resting serow. There is nothing in the literature regarding which predators prey on C. sumatraensis, however Lovari and Locati (1994) mention that serows sometimes occupy the same habitat as big cats such as leopards and tigers, which likely prey on them. (Lovari and Locati, 1994)

Predation does not appear to have a major impact on population density of the closely related Japanese serow, Capricornis crispus. (Ochiai and Susaki, 2002)

Other ungulates such as wild pigs, rusa deer, and barking deer or muntjacs share the Sumatran serow's habitat. There may be some overlap in diet between Capricornis species and other ungulate genera. (Chen, et al., 2009; Santiapillai and Ramono, 1994)

In captivity, Capricornis sumatraensis has been observed to host external parasites, such as large fleas. Nematode larvae have also been found in feces of captive individuals. (West, 1979)

Throughout Asia, multiple species of serow are hunted for medicinal purposes and for their meat. The meat of the Formosan serow, Capricornis swinhoei, is highly valued in Taiwan. Some local people hunt C. sumatraensis for its meat, despite it being protected, because the locals believe that serow meat is better than meat that is more readily available, such as meat from goats. However, this hunting poses a threat to populations. (Corlett, 2007; Wang and Chen, 1981; West, 1979)

A close relative, Capricornis crispus, occasionally eats crops. (Deguchi, et al., 2002)

In 2008, C. sumatraensis was listed as vulnerable by the IUCN Redlist. It is estimated that there are between 500 and 750 individuals in Malaysia, but there are no data on population size in Indonesia. The main threat for Sumatran serows is loss of habitat. Capricornis sumatraensis requires thick forest, and forests in its range are being cut due to agriculture and the demand for timber. Many Sumatran serows are also injured or killed by poachers when they are caught in traps meant for other animals. Capricornis sumatraensis is protected by law in Indonesia and Malaysia, as are certain parts of the animal’s habitat. Both Indonesia and Malaysia have conservation plans that aim to educate people living near serows, reduce habitat loss, and protect remaining habitat, to prevent the serow population from declining further. (Duckworth, et al., 2008; Santiapillai and Ramono, 1994)

The classification of serows has changed greatly over time. In 1908, seven subspecies of Capricornis sumatraensis were recognized based on geographical range. Subsequently, many of these subspecies were elevated to species. Later, serows were classified into two species, one of which was Capricornis crispus. Currently, there are six recognized species of serow, including Capricornis sumatraensis. ("Capricornis sumatraensis", 2010; Pocock, 1908; Thomas, et al., 1986)