Bubalus mindorensis
tamaraw

Tamaraws are found only on the island of Mindoro in the Philippines. Although fossil evidence suggests that they may also have occupied the island of Luzon. The current distribution is limited to the 9,375 km2 island of Mindoro. On Mindoro, they are further restricted to three game refuges covering about 200,000 ha. The refuges were created in 1969 by the Philippine Parks and Wildlife Office. (Custodio, et al., 1996; Kuehn, 1976; Kuehn, 1986)

Before 1900, tamaraws were widely distributed throughout the island, inhabiting all elevations (0-2000 m) and all habitat types, including Mindoro's vast forests and less common wetlands, grasslands, riparian areas, and bamboo thickets. Human settlement in the early 20th century led to massive deforestation as the forests were converted to agricultural land. Currently, tamaraws inhabit Mindoro's abundant grasslands and secondary successional forests and can be found at 300 to 1000 m in elevation. Some researchers speculate that their preferred habitat is forest edge, providing access to forage, water, and cover. (Custodio, et al., 1996; Kuehn, 1976; Kuehn, 1986)

Tamaraws are distinguished from related buffalo by their smaller stature and straight horns. These characteristics (among others) led taxonomists to categorize these animals as a unique species, and not a sub-species of Asiatic water buffalo (B. bubalis). Total height at the shoulders is 106 cm. Head and body length is 220 cm, and tail length is 60 cm. Few reported weights are available in the literature. Those given are for females only and range from 180 to 300 kg. Horn shape can be used to determine the sex of skulls, with male horns being thicker, longer, flatter, and closer together than those of females. Horn length is 35 to 43 cm. The dental formula is 0/3, 0/1, 3/3, 3/3 = 32.

Adult pelage is dark brown or black, with no differences between sexes. Juvenile pelage is reddish-brown, with dark brown legs and a black dorsal line. Pelage turns slate colored at 3 to 4 years of age, and adult coloration is achieved at 5 years of age. Horn length and thickness can be used to age tamaraws in the field. As they mature, the horns grow longer relative to the length of the ears and broaden at the base. (Custodio, et al., 1996; Kuehn, 1986)

Little is known about mating systems of tamaraws in the wild. Males and females generally remain separate during most of the year, coming together only during breeding season. How mates are selected is unkown. (Custodio, et al., 1996)

Bubalus mindorensis breeds during the dry season, from December to May. Gestation is 276 to 315 days, timed so that births occur during Mindoro's wet season (June to November), allowing the neonates access to a fresh, abundant food supply. Cows give birth to a single calf every two years. Young leave the mothers at the age of 2 to 4 years, meaning calves from several years may accompany a cow at one time. Limited evidence (a single observation) of a cow grazing 50 m from a newborn calf hiding in the grass suggests that young may behave as "hiders". Age of primiparity or sexual maturity is not given in the literature, but one source says they reach "adulthood" at 6 years of age. (Custodio, et al., 1996; Kuehn, 1986)

Females nurse and care for their young, males do not provide parental care. Calves remain with their mothers for 2 to 4 years, although the extent of parental care provided during this period is unclear. Females stay with the mother longer than males. Tamaraws appear to behave as typical "hiders", although this hypothesis comes from a single observation of a female tamaraw feeding a short distance from her hidden calf. (Custodio, et al., 1996; Kuehn, 1986)

The only reported life expectancy for tamaraws in the literature is 20 years, but whether this is for a wild or captive animal is unclear. (Custodio, et al., 1996)

Adult tamaraws, both cows and bulls, are largely solitary. This differs from other bovids, and has been explained as an adaptation to living in forested environments where large social groups are impractical. Associations between males and females are infrequent and short-lived, occurring during the breeding season. Cows are often accompanied by young of several years. Males and females are driven from family groups at 3 and 4.5 years of age, respectively. Juvenile tamaraws are known to form groups for a year or more, but they become solitary when they reach adulthood. Tamaraws are also described as being aggressive towards humans. Traditionally, tamaraws were active during the day, feeding in close proximity to human ranching operations. Activity patterns now appear more nocturnal, with days spent resting in dense vegetation. In a limited number of observations of tamaraw behavior, Kuehn (1986) did not observe fights between bulls. However, bulls were observed chasing other bulls, especially during breeding season and on burned grasslands. Female tamaraws threatened conspecifics by lowering their heads and shaking their horns. Cows have also been observed chasing and prodding their calves. Tamaraws will use mud wallows like related buffalo species. (Custodio, et al., 1996; Kuehn, 1986)

Very little is known about communication in tamaraws. Aggression is expressed through head movements and adult bulls will occassionally communicate dominance by chasing subordinate males from food sources or potential mates. It is likely that tamaraws communicate also through some auditory and chemical cues. Most bovids have keen senses of smell and hearing, although their eyesight may be poor. (Custodio, et al., 1996; Kuehn, 1986)

Tamaraws are herbivorous, feeding on grass species such as Cynodon arcuatus, Digitaria sanguinalis, Eleusine indica, Sorghum nitidum, Paspalum scrobilatum, Alloteropsis semialata, and Vetiveria zizanoides. During the rainy season they feed on shoots of bamboo (Schizostachyum spp.). The Batangans, a tribal group practicing slash-and-burn agriculture on Mindoro, frequently burn small plots for agriculture. Tamaraws often visit these newly burned locations to feed on grass shoots. (Custodio, et al., 1996)

Tamaraws have no known native predators on Mindoro, and frequently fed in the open during daylight, suggesting little concern for predation. Humans are the only predator of tamaraws, and the development of Mindoro has also led to a more secretive and nocturnal lifestyle for tamaraws. (Custodio, et al., 1996)

Given their current small population size, tamaraws are not likely to play a dominant role in the ecosystem processes of present-day Mindoro. The historical importance of tamaraws in the Mindoro ecosystem is unclear, although they may have influenced vegetation succession through their grazing and wallowing.

Tamaraws have been hunted for food and sport in the past, but these activities have been outlawed since 1936. (Custodio, et al., 1996; Kuehn, 1986)

There are no known adverse affects of tamaraws on humans.

Tamaraws are listed as CR C1 (critically endangered with an observed decline of 80% over the last 10 years) by the IUCN and listed in Appendix I by the Convention on International Trade of Endangered Species of Wild Flora and Fauna (CITES). Their numbers have declined from an estimated 10,000 in 1900 to approximately 20 to 200 individuals today, making this species one of the rarest mammals in the world. The population trend is continuing downwards. Major threats have included habitat loss and degradation due to agriculture, logging, and development, hunting and poaching, and disease. A rinderpest epidemic in 1930 was particularly devastating to the population. Tamaraws are protected under Philippine law, and several reserves have been created to maintain habitat for wild, free-ranging tamaraws. The Asian Wild Cattle Specialist Group (AWCSG) of the IUCN listed habitat management, life-history research, limiting-factor research, and monitoring as the recommended research and management options for tamaraws. (Custodio, et al., 1996; Heinen and Srikosamatara, 1996; "IUCN Red List of Threatened Species", 2002; Nowak and Paradiso, 1983)

Bubalus mindorensis was initially described independently by Heude and Steere in 1888 and 1889, respectively, although Heude is listed as the specific authority. (Custodio, et al., 1996)