in its canopy homes. Behavior The Philippine tarsier is a shy, nocturnal animal that leads a mostly hidden life. During the day, it sleeps in dark hollows close to the ground, near tree trunks and shrubs deep in the impenetrable bushes and forests. It becomes active only at night; with its keen sight and ability to manoeuvre around trees, it is able to avoid humans. It is arboreal, habitually clinging vertically to trees and capable of leaping from branch to branch. The Philippine tarsier is solitary. However, populations and individuals have been found to have either monogamous or polygamous mating patterns. Communication Three different audible calls have been documented. One is its "loud call"—a piercing single note. The second sound is a soft, sweet, bird-like twill, a sound of contentment. When several tarsiers come together, the combined effect of this chirping is a locust-like sound. These mammals can also vocalize in an ultrasound frequency range of 70 kHz and can pick up frequencies above 90 kHz. This form of vocal communication is used as a distress call made by infants when they are separated from their mothers. It is also the call made by males to their mates during mating season. Tarsiers also communicate through a scent from the circumoral gland located around the mouth, which the female uses to mark her mate. The males mark their territory with their urine. Tarsiers perform tactile communication through social grooming, removing dead skin and parasites, a behaviour observed in females on adult males, as well as in females on their offspring. Reproduction The Philippine tarsier's gestation period lasts about six months, while the female's estrous cycle lasts 25–28 days. The mating season lasts from April to May. The males deposit a mating plug in the female's vagina after intercourse. The female gives birth to one offspring per gestation. The infant is born with hair and with its eyes open. The females carry their infants in their mouths. A newborn can already cling to branches and in less than a month after birth, it can start leaping. Newborns are breastfed until 60 days after birth. After two years of age, the tarsier is sexually mature and able to reproduce. Status In 1986, 1988, and 1990, the Philippine tarsier was assessed as endangered by the IUCN Conservation Monitoring Centre. On September 13, 1991, the Department of Environment and Natural Resources issued DENR Administrative Order