Tarsius bancanus Horsfield, 1821, eastern Sumatra, Borneo, and adjacent island.
OTHER COMMON NAMES
English: Horsfield's tarsier; French: Tarsier occidental; German: Sundakoboldmaki.
12.6-14.6 in (32-37 cm); 3.8-4.8 oz (107-135 g); buff, sometimes sand-colored; tail tuft short, but well developed. Biggest eyes in relation to head size in any mammal.
Southeastern Sumatra and Borneo, and the islands of Bangka, Belitung, Karimata, and Serasan.
Secondary and primary rainforest, shrubs, plantations.
Scent marking is very traditional, indicating very stable home ranges. Males and females sleep separately. Rather silent, nocturnal and crepuscular.
Western tarsiers eat anything that moves and does not defend itself too effectively, from ants and beetles to bats and birds, even animals up to the tarsier's own body weight. On one occasion, a western tarsier was observed catching and eating a poisonous snake.
Different field studies suggest pair bonds or polygynous social organization. Births occur throughout the year, with a conspicuous increase in frequency by the end of the rainy season between February and June. The giant baby, weighing about one quarter of its mother's weight, is able to climb on the first day of its life. Some skeletally adult males have small testes, suggesting the existence of a social category of reproductively inactive "spare males."
This tarsier was considered an omen animal by the formerly head-hunting Iban people in Sarawak, Borneo. Since their extremely flexible cervical spine allows head rotations of at least 360°, their head was considered to be loose. If a head hunter encountered a tarsier, he was obliged to turn around immediately, because otherwise, the spell of the spirits might hit him and his community. ♦
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