AboutZoos, Since 2008


Borneo’s Orang­utans spot­ted on the ground with cam­era traps

pub­lished 12 August 2013 | mod­i­fied 28 June 2014

Orang­utans might be the king of the swingers, but pri­ma­tol­o­gists in Bor­neo have found that the great apes spend a sur­pris­ing amount of time walk­ing on the ground. The research, pub­lished on 19 June in the Amer­i­can Jour­nal of Pri­ma­tol­ogy found that it is com­mon for orang­utans to come down from the trees to for­age or to travel, a dis­cov­ery which may have impli­ca­tions for con­ser­va­tion efforts.

Northeast Bornean orangutanAn expe­di­tion led by Brent Loken from Simon Fraser Uni­ver­sity and Dr. Stephanie Spe­har from the Uni­ver­sity of Wis­con­sin Oshkosh, trav­elled to the East Kali­man­tan region of Bor­neo. The region’s Wehea For­est is a known bio­di­ver­sity hotspot for pri­mates, includ­ing the North­east Bornean orang­utan, Pongo pyg­maeus morio, the least stud­ied of orang­utan sub­species. This orang­utan sub­species is con­ser­va­tion sta­tus is Endan­gered accord­ing the IUCN Red List of Threat­ened Species.

Orang­utans are elu­sive and one rea­son why recorded evi­dence of orang­utans on the ground is so rare is that the pres­ence of observers inhibits this behaviour
Brent Loken, lead author, Simon Fraser University »

“How­ever, with cam­era traps we are offered a behind the scenes glimpse at orang­utan behaviour.”

The team posi­tioned ground-​based cam­eras across a 38 km2 region of the for­est and suc­ceeded in cap­tur­ing the first evi­dence of orang­utans reg­u­larly com­ing down from the trees.

The amount of time orang­utans spent on the for­est floor was found to be com­pa­ra­ble to the ground-​dwelling pig-​tailed macaque, Macaca nemest­rina, which is equally abun­dant in Wehea For­est. Over 8-​months orang­utans were pho­tographed 110 times, while the macaques were pho­tographed 113 times.

The rea­son orang­utans come down from the trees remains a mys­tery. How­ever, while the absence of large preda­tors may make it safer to walk on the for­est floor, a more press­ing influ­ence is the rapid and unprece­dented loss of Borneo’s orang­utan habitat.

“Bor­neo is a net­work of tim­ber plan­ta­tions, agro-​forestry areas and mines, with patches of nat­ural for­est,” said Loken. “The trans­for­ma­tion of the land­scape could be forc­ing orang­utans to change their habi­tat and their behaviour.”

Great footage with incred­i­ble images from 3 months of cam­era trap­ping in Wehea For­est, Bor­neo. The video shows many species, the orang­utan of course, small deer species, wild boar, a civet, a sun bear, and a medium-​sized cat what appears to be a Sunda clouded leopard:

Excel­lent choice of music » What a won­der­ful world by the Ramones! Who said sci­en­tists don’t know good music.biggrin

This research helps to reveal how orang­utans can adapt to their chang­ing land­scape; how­ever, this does not sug­gest they can just walk to new ter­ri­tory if their habi­tat is destroyed. The orang­utan sub­species Pongo pyg­maeus morio may be adapted to life in more resource scarce forests, hav­ing evolved larger jaws which allow them to con­sume more tree bark and less fruit but they are still depen­dent on nat­ural forests for their long term survival.

“While we’re learn­ing that orang­utans may be more behav­iourally flex­i­ble than we thought and that some pop­u­la­tions may fre­quently come to the ground to travel, they still need forests to sur­vive,” said Dr. Spe­har. “Even in for­est plan­ta­tion land­scapes they rely heav­ily on patches of nat­ural for­est for food resources and nest­ing sites.”

Wehea For­est is one of the only places in Bor­neo where ten pri­mates species, includ­ing five species found only in Bor­neo, over­lap in their ranges. Since Wehea For­est is a bio­di­ver­sity hotspot, paper­work have been sub­mit­ted to legally change the sta­tus of Wehea For­est from “pro­duc­tion for­est” to “pro­tected for­est”. How­ever, given that 78% of wild orang­utans live out­side of pro­tected areas, it is crit­i­cal that all of Borneo’s remain­ing forests are either pro­tected or sus­tain­ably managed.

“We do not know how long this may take, but pro­tect­ing Wehea For­est and Borneo’s remain­ing forests is vital to the long term sur­vival of the orang­utans,” con­cluded Loken. “For­tu­nately 60% of Wehea For­est falls under Indonesia’s log­ging mora­to­rium, which helps give legal pro­tec­tion to a large part of the for­est for a few more years.”

(Source: Wiley press release, 29.07.2013)

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