ABOVE: Proboscis Monkeys and
Ficus racemosa fig trees share the same river bank habitat in Borneo. In areas where hunting is absent such as the Segama and Kinabatangan rivers in Sabah and the Temburong River in Brunei both Proboscis Monkeys and Ficus racemosa trees are commonly seen on the river banks along the lower reaches of the rivers . Photo by Mike Gordon.
Note that the fig bunch contains both ripe and unripe fig fruit. According to Valentine Thiry a PHD student based at Danau Girang on the Kinabatangan River in Sabah out of 83 Proboscis feeding occurrences recorded, 9 occurrences were on Ficus racemosa (4 unripe, 2 ripe and 3 unidentified). These 9 fruit feeding events were observed on 6 different days.
Note that although Ficus racemosa produces distinct crops every six weeks in Borneo, the figs themselves ripen over a period of a round 10 days. Also a second crop often starts before the first crop has finished thus there are nearly always both unripe and ripe figs on the same tree at the same time. During research for her thesis on plants dispersed by Proboscis Monkeys on the Kinabatangan river, Valentine Thiry attempted to germinate 62 Ficus racemosa seeds collected from Proboscis feces (see picture below). Of the 62 seeds collected, 19 seeds germinated but 43 did not.
Seeds collected from Proboscis Monkey faeces at the Kinabtangan river. Note that some of the seeds appear to be full sized (ripe) whilst other seeds appear to be unripe. It is probable that some seeds came from ripe Ficus racemosa figs and others from unripe F. racemosa figs therefore one would expect uneven germination. Thus Proboscis monkeys appear to be both seed predators (of unripe figs) and seed dispersers of ripe figs. Photo by Valentine Thiry.
Fortunately many birds and mammals also disperse Ficus racemosa seeds such as this Rhinoceros Hornbill which only feeds on ripe figs. Photo by Mike Gordon.
Ficus racemosa seeds are also dispersed by small Cynopterus fruit bats which eat the ripe figs. Photo by Mike Gordon.
Two Ficus racemosa trees growing on the banks of the Kinabatangan river near Sukau in Sabah, Malaysian Borneo. Note that branches often hang directly over the water. On many stretches of the river there is at least one Ficus racemosa fig tree every 100 m. F. racemosa fruits prolifically, almost continuously with a new crop every six weeks. Almost all the abundant wildlife that lives in the Kinabatangan forests ultimately depends on the of the phenomenal productivity Ficus racemosa trees.
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