June 28, 2010
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.
How hornbills keep Asian rainforests healthy and diverse, an interview with Shumpei Kitamura
(04/26/2010) Hornbills are one of Asia's most attractive birds. Large, colorful, and easier to spot than most other birds, hornbills have become iconic animals in the tropical forests of Asia. Yet, most people probably don't realize just how important hornbills are to the tropical forests they inhabit: as fruit-eaters, hornbills play a key role in dispersing the seeds of tropical trees, thereby keeping forests healthy and diverse. Yet, according to tropical ecologist and hornbill-expert Shumpei Kitamura, these beautiful forest engineers are threatened by everything from forest loss to hunting to the pet trade.
The Asian Animal Crisis
(03/18/2010) The United Nation declared 2010 as the International Year of Biodiversity (IYB). One of the goals of the IYB is to celebrate the achievements of the Convention of Biological Diversity signed by 192 countries since 1992. But what have we accomplished since 1992? Did we put an end to biodiversity loss? The truth is that there is not much to celebrate at all. Asia is a perfect example where the animal crisis and the loss of biodiversity have worsened over decades. The first question that should come to mind is: how many species have vanished in Asia because of human activities? Records of recently extinct species in Asia show 71 species that have disappeared in the wild. Examples include the Yunnan lake newt (Cynops wolterstorffi) from China, the Bonin thrush (Zoothera terrestris) from Japan, or the redtailed black shark (Epalzeorhynchos bicolor) from Thailand.
Why seed dispersers matter, an interview with Pierre-Michel Forget, chair of the FSD International Symposium
(03/07/2010) There are few areas of research in tropical biology more exciting and more important than seed dispersal. Seed dispersal—the process by which seeds are spread from parent trees to new sprouting ground—underpins the ecology of forests worldwide. In temperate forests, seeds are often spread by wind and water, though sometimes by animals such as squirrels and birds. But in the tropics the emphasis is far heavier on the latter, as Dr. Pierre-Michel Forget explains to mongabay.com. "[In rainforests] a majority of plants, trees, lianas, epiphytes, and herbs, are dispersed by fruit-eating animals. […] As seed size varies from tiny seeds less than one millimetres to several centimetres in length or diameter, then, a variety of animals is required to disperse such a continuum and variety of seed size, the smaller being transported by ants and dung beetles, the larger swallowed by cassowary, tapir and elephant, for instance."