Habitat‐specific ranging patterns of Dian's tarsiers (Tarsius dianae) as revealed by radiotracking

Abstract

Dian's tarsier Tarsius dianae, one of the smallest primates on earth, is endemic to the central regions of Sulawesi, Indonesia. To evaluate the effects of increasing land use by humans on the ranging patterns of this nocturnal insect hunter, four study plots along a gradient of anthropogenic disturbance were selected for this study. In these plots, 71 tarsiers were captured with mist nets, and 30 of these were fitted with 3.9 g radiotransmitters and subsequently tracked over the course of 2 weeks per animal. The average home ranges were 1.1-1.8 ha in size, with the smallest ranges in slightly disturbed habitat and the largest ranges in a heavily disturbed plantation. These findings coincide with different estimates of insect abundance in the study plots. Nightly travel distances were smallest in undisturbed old-growth forest and slightly increased along a gradient of human disturbance. The tarsiers were most active shortly after dusk and just before dawn. The results of this comprehensive radiotracking study on tarsiers show that T. dianae adapts its ranging behavior to the degree and type of human land use. Integrated data on home range size and travel distance indicate that slightly disturbed forest is as favorable to these animals as undisturbed habitat. However, with increasing anthropogenic effects, the living conditions of the tarsiers appear to deteriorate, resulting in the necessity for larger home and night ranges. The results of this study provide an important tool for directing conservation efforts targeted at the survival of this primate in central Sulawesi.

Elucidating geological and biological processes underlying the diversification of Sulawesi tarsiers

“…We captured 2 males with T. lariang-typic genetic signatures several hundred meters outside of their species' usual range. This observation falls into a radius that tarsiers easily cover within a single night (42,47). Although these 2 individuals might also have been translocated and released pets, the steep gradients in allele frequencies at the species boundary and the consistent lack of alien genes in the reference populations suggest that accidental introductions do not play an important role in shaping the genetic structure of tarsier populations in a human-altered landscape.…”

The Population Ecology of Dian’s Tarsier

“…Group sizes of T. dentatus range from 2 to 7 individuals (Merker 1999(Merker , 2003(Merker , 2006Merker et al 2004Merker et al , 2005 and are thus similar in size and composition to groups of northern Sulawesi's spectral tarsier (e.g., MacKinnon and MacKinnon 1980;Nietsch 1993;Gursky 1995Gursky , 2000Gursky , 2007. Almost always, groups were found to comprise one adult male, between one and three adult females, and their offspring.…”

Activity Patterns of Captive Philippine Tarsiers (<b><i>Tarsius syrichta</i></b>): Differences Related to Sex and Social Context

“…Activity patterns of the wild T. syrichta revealed by Neri-Arboleda et al [2002] showed that both sexes were most active in hourly distance travelled in the first hour after dusk. The early activity peak for the wild tarsiers is explainable by their being quickly able to reach beneficial hunting grounds [Merker, 2006]. With regard to the peak at the end of the night, Crompton and Andau [1987] and Merker [2006] suggested that since the foraging areas were far away from the sleeping sites, travelling back increased the frequency of this activity.…”

“…During the mating season, the tarsiers spent significantly more time travelling at the end of the night. Studies conducted on the wild T. bancanus [Crompton and Andau, 1987] and T. dianae (= dentatus) [Merker, 2006] revealed two peaks for locomotor activity and distance travelled: the first shortly after dusk, and the second before going to sleep at dawn. A twopeak activity rhythm was also described by Nietsch [cited in Merker, 2006] for the wild T. spectrum.…”

“…Studies conducted on the wild T. bancanus [Crompton and Andau, 1987] and T. dianae (= dentatus) [Merker, 2006] revealed two peaks for locomotor activity and distance travelled: the first shortly after dusk, and the second before going to sleep at dawn. A twopeak activity rhythm was also described by Nietsch [cited in Merker, 2006] for the wild T. spectrum. Activity patterns of the wild T. syrichta revealed by Neri-Arboleda et al [2002] showed that both sexes were most active in hourly distance travelled in the first hour after dusk.…”