In one of the most remote and undisturbed forests of Borneo, the Maliau Basin in the Malaysian state of Sabah, researchers picked a single fig tree (Ficus caulocarpa)
and surveyed the species feeding from it over a 5-day-period. Their findings, published in Tropical Conservation Science, shows that a fig tree over a short period of time feeds a high percentage of endangered species, prompting researchers to recommend replanting figs in disturbed forests as a way to save Borneo’s frugivores (fruit-eating species) from extinction.
Figs are known as keystone species in the tropics, since they fruit year round providing a constant source of fruit to frugivores. For example, studies in Borneo have found that 42 percent of known birds and 73 percent of known mammals feed on figs. But the fig-eating animals repay the trees by spreading their seeds—and genetics—across the forest.
Over five days of studying the Ficus caulocarpa tree in the Maliau Basin, researchers counted 493 visits by 44 bird species and three mammals, all squirrels. Their findings showed that this particular fig, which produces smaller fruits, fed a more selective host than many other fig trees in the region. Most of the visitors were small birds, as opposed to large birds or mammals.
“The complete absence of larger frugivores on F. caulocarpa in our study does suggest that fig-frugivore interactions may be more finely structured that was previously thought, based on reports from more disturbed sites,” the authors write.
Importantly, during the five days researchers observed 15 bird species (34 percent of total birds viewed) that are listed as Near Threatened or worse by the IUCN Red List.
“This suggests that not only are [strangler figs] important resources for wildlife, but that they support a disproportionate number of threatened species,” the authors write. “This is perhaps not surprising since frugivores are particularly sensitive to hunting pressure and hence tend to dominate threatened species lists in tropical forests.”
The researchers recommend that such figs be planted in degraded forests to boost fruit availability for endangered species.
Given that frugivores are especially sensitive to hunting and deforestation, the authors also suggest that monitoring species at fig trees in other areas of Borneo could provide a quick analysis of the ecosystem’s health.
“Brief observations at a small number of [strangler figs], preferably across a range of fruit sizes, could be used to assess how intact the frugivore community is at a site and by extension how well the site is protected,” they write.
Sreekar, R., Thi Phuong, L. N. Harrison, R. D. 2010. Vertebrate assemblage at a fruiting fig (Ficus caulocarpa) in Maliau basin, Malaysia. Tropical Conservation Science Vol. 3 (2):218-227.
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