sleeping sites

For the two arboreal species there were accurate descriptions in the literature of both sleeping sites and nests. Fortunately, those accounts describe nests of species for which I have the least data, so together, both sleeping sites and nest structures are known for all six study species.

All six species had distinctive kinds of sleeping sites. These fall into three sets of pairs with similar habits (table 6.3). The preference of the two arboreal species for nesting in canopy tree hollows, as do most other canopy small mammals, may simply indicate that tree hollows are the safest, warmest, and driest places to nest in the canopy. But pentails have thus far been reported to nest only in tree or branch hollows, while T. minor will use other types of sites, some of them, like those of other Tupaia species, exposed in the midstory or understory foliage.

Slender treeshrews more often than any other species used exposed sleeping sites in vine tangles or treelets, and they seemed to use opportunistic shelters such as a bird's nest or a pile of leaf debris. The frail and unprotected nature of these sites is, I believe, the reason that if disturbed, this species alone customarily abandoned its nest with a flying leap into the night (it was clear from what I could hear that the animals could not see where they were headed in the dark). Large treeshrews preferred an array and height of sleeping sites similar to those of slender treeshrews (see table 6.3), but most were protected within woody crevices or tree hollows. I crashed around many of these at night, without any of the animals moving, but once, inadvertently, I brushed by a T. tana that was resting in an exposed leaf nest in a low sapling in late afternoon, and it jumped to the ground whistling.

It is a curious circumstance that T. tana, which has elongated claws, digs to forage, and is the most terrestrial species, nests only above ground; whereas T. longipes, which does not have large claws, does not dig to forage, and is slightly less terrestrial, lives in underground burrows. Morphology is thus not a good predictor of burrowing behavior. Use of below-surface nests by T. longipes and T. montana might seem to be evidence for an evolutionary connection between these two, but this similarity is only superficial, because the habit of building a nest in a crevice is common to several Tupaia, but actual burrowing is thus far known only in T. longipes. Urogale everetti, likewise said to live in holes in the ground (Wharton 1950), was thought by Lyon (1913) (with reservations), to most closely resemble T. tana (with which it shares elongated foreclaws). However, DNA hybridization studies suggest that the Philippine genus Urogale and the Tupaia glis/longipes species group form a clade together distinct from that of T. tana/montana (Han et al. pers. com.). If so, underground burrow nesting may be a phylogenetic trait.

Our finding of a group of pentails that shared a sleeping tree conforms to the reports by Lim (1967), Muul and Lim (1971), and Gould (1978) that this species nests communally. Because pentails have been captured in groups in a nest and share nests by choice in captivity (Gould 1978), I assume that the pentails we found at the same den site were nest-mates.

The nesting behavior of pentails is thus divergent from that of Tupaia species in that no Tupaia adult was ever recorded sharing a nest with another individual, and whereas pentails used only one sleeping site, Tupaia each had many sites and changed them often.