Description and Behavior
The Bornean bay cat is the mystery cat of the family. Its description rests on just a few skins and skulls, most
collected in the late 1880s, scattered in several museums around the world (Sunquist et al. 1994a).
Tissue and blood samples for genetic analysis were acquired only in late 1992, when a female captured by
trappers on the Sarawak-Indonesian border was brought to the Sarawak museum on the point of death. The
cat weighed 1.95 kg, but was estimated to have weighed between 3-4 kg when healthy (Sunquist et al.
1994b). No observations of the bay cat’s behavior or ecology have been made since Hose (1893).
The Bornean bay cat has two color phases: chestnut-red, the more common, and grey (Pocock 1932,
Sunquist et al. 1994b). The coat of the 1992 female was speckled with black markings (Sunquist et al.
1994a). Her tail was long: at 391 mm, 73% of head-body length (533 mm). On all specimens, the backs of
the rounded ears are darker-colored, and a whitish stripe runs down the ventral surface of the terminal half of the
tail. The bay cat resembles the Asian golden cat not only in these characters, but also in skull dimensions, and may
well be an island form (Weigel 1961, Hemmer 1978a, Groves 1982). The Asian golden cat occurs widely
throughout South-East Asia, including Sumatra but not Borneo. Borneo has been separated from Sumatra and
other islands on the Sunda Shelf for 10,000-15,000 years (Sunquist et al. 1994a). Genetic analysis
indicates a close relationship to the Asian golden cat (Collier and O’Brien 1985).
Habitat and Distribution
Found only on the island of Borneo. Collection and sighting records with fairly precise locations, shown in
Figure 6, are all from the highlands, and most are near rivers,
although the latter may reflect a collecting bias (Payne et al. 1985; C. Groves, P. Pfeffer, J. Payne in litt.
1993; Sunquist et al. 1994b). The record from Mt Kinabalu is an unconfirmed sighting at 1,800 m
(Payne et al. 1985). In north-eastern Kalimantan in the late 1950s, P. Pfeffer (in litt. 1992)
twice saw the fur of the bay cat in Dyak ceremonial caps. S. Yasuma (in litt. 1987, 1988, 1993) has
looked in vain for evidence of the bay cat in the Bukit Suharto Protection Forest, located 60 km south of
Samarinda in the eastern coastal lowlands of Kalimantan, where all other sightings of Bornean cats have been
recorded. According to Hose (1893), dense primary forest is preferred, but recently several biologists
have sighted a bay cat at night in logged dipterocarp forest along the access road to the Danum Valley Field
Studies Centre in eastern Sabah (J. Gasis, P. Hurrell, S. Yorath pers. comm. to J. Payne 1993).
Global: Category 2
Regional: Category 1
IUCN: Insufficiently Known
The bay cat has long been considered rare (Hose 1893). A faunal survey of Sabah (Davies and
Payne 1982) found no evidence of the bay cat. Rabinowitz et al. (1987) interviewed villagers
in Sabah and Sarawak about local occurrence of clouded leopards, using pictures in a field guide (Payne
et al. 1985). While many informants had seen clouded leopards, leopard cats, flat-headed cats and
marbled cats, none pointed to the picture of the Bornean bay cat (J. Payne in litt. 1993). The trappers
who captured the bay cat in 1992 were apparently aware of its rarity and value to an animal dealer
(Sunquist et al. 1994b).
Protection Status: CITES Appendix II
Fully protected over most of its range
Hunting and trade prohibited:
Indonesia, Malaysia (Sabah and Sarawak)
No legal protection outside reserves:
Brunei (Nichols et al. 1991)
Unknown, probably deforestation (Collins et al. 1991). On a positive note, P. Pfeffer (in litt.
1992) notes that the same area of eastern Kalimantan where the fur caps were seen in 1955-1957 was
visited again in 1986 and 1989. The forest was still undisturbed and less populated, as most villages had
migrated toward the coastal lowlands.