This is “William” one of a pair of North Borneo Gibbons Hylobates funereus that “own” the gibbon territory next to the Belalong Canopy Walkway in the Ulu Temburong National Park in Brunei. In his right hand William is holding a piece of ripe Ficus punctata fruit collected from a nearby fruiting liana.
GIBBON FAMILY TERRITORIES IN BORNEO: Researchers believe that the Ulu Temburong forests host the most dense population of gibbons in the whole of Borneo.
Location
Territy Ha
Families/km2
Habitat
Gng Palung
28
3
Lowland dipterocarp
Sabangau
47
2
Peat-swamp
Tg Puting
48
2
Peat-swamp
Kutai
36
3
Lowland dipterocarp
Kayan Mentarang
42
2
Hill forest
Temburong Bukit Tudal (1)
31
3
Hill forest
Temburong Belalong (2)
19
5
Lowland dipterocarp
Average
36
2
(1) Bennett et al (1987)A Wildlife Survey of Ulu Temburong
Gibbon familes average 3.5 to 4 individuals and strongly defend their territories with loud early morning calls. The high density and small family territories of gibbons at both sites in Ulu Temburong (Brunei) may be due to the absence of orangutans in Brunei. Orangutansare known to eat unripeF. punctatafigs. Gibbons only eat the ripe figs and therefore cannot compete with orangutans if they are present.
This is “Kate”, Williams partner hanging from one arm next to a Ficus punctata liana covered in ripening figs at the Belalong Canopy Walkway in Brunei. Kate is larger and much bolder than “William”. At the time these photos were taken, William and Kate were childless. Their first baby Wak-Wak was born in the middle of 2017. All photos by Quentin Phillipps, taken in December 2016.Note that Kate is holding a large, dark purple, ripe Ficus punctata fig fruit in her left hand. This one Ficus punctata liana fruits prolifically approximately 4 times a year. The figs do not ripen in one big bang but individually over a period of 2 months before starting another crop around 2 months later. Thus this one prolific Ficus punctata liana provides food intermittently for this one gibbon family for about half the year. Other animals that fed on the figs include binturongs, striped palm civets, long tailed macaques and Prevost’s Squirrel.View from the far tower of the the Belalong Canopy Walkway at Temburong, Brunei. The surrounding forests host both the greatest variety and density of figs known in Borneo. This photo alone includes 5 different fig species ! Maybe this is the reason that the Temburong gibbons are able to survive in relatively small territories.
Illustration by Karen Phillips from page 185, of the Phillipps’ Field Guide to the Mammals of Borneo by Quentin and Karen Phillipps. (2016)View from the Belalong Canopy Walkway looking north west towards Brunei Bay. The long ridge in the far distance defines the border between Temburong, Brunei and Limbang, Sarawak.
