Locomotion and habitat utilization in free-rangingTarsius bancanus: A preliminary report

Four adultTarsius bancanus were followed for a total of over 120 hrs in Sepilok Forest Reserve, Sabah, using radiotracking techniques. Seven hundred and twenty-two records of locomotor and postural behaviour were gathered.Tarsius bancanus travels a mean of 1,800 m per night, over large (4.5 to 11.25 ha) ranges. They move at a mean height of 0.89 m, utilizing primarily vertical sapling trunks of diametre 2 to 4 cm. Lateral movement is carried out largely by leaping.Tarsius were found on the ground in 5.3% of cases, but movement on the ground is very largely restricted to short investigative movements by walking. Climbing is mostly related to foraging behaviour and characteristically occurs on relatively small supports.Tarsius bancanus' locomotion is similar to, but more specialized than that ofT. spectrum, Galago alleni, andGalago senegalensis, all of which have rather similar patterns of habitat utilization. We suggest that the energetic constraints of small body size together with the need to patrol large home ranges may have lead both toTarsius bancanus extreme degree of locomotor specialization and to its exclusive animalivory.