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Suma­tran tigers, found exclu­sively on the Indone­sian island of Suma­tra, are poised on the brink of extinc­tion. By opti­mistic esti­mates, per­haps 400 indi­vid­u­als sur­vive. But the exact the num­ber and loca­tions of the island’s dwin­dling tiger pop­u­la­tion has been up for debate.

Vir­ginia Tech and World Wildlife Fund (WWF) researchers have found that tigers in cen­tral Suma­tra live at very low den­si­ties, lower than pre­vi­ously believed. Their results, sum­ma­rized in the paper “Threat­ened preda­tor on the equa­tor: multi-​point abun­dance esti­mates of the tiger Pan­thera tigris in cen­tral Suma­tra,” were pub­lished in the April 2013 issue of Oryx — The Inter­na­tional Jour­nal of Conservation.

These find­ings by the research team led by Sunarto, who earned his doc­tor­ate from Vir­ginia Tech in 2011, sug­gest that high lev­els of human activ­ity limit the tiger pop­u­la­tion. The results of this study, which cov­ered areas and habi­tat types not pre­vi­ously sur­veyed, are rel­e­vant to the inter­ven­tions needed to save the tiger.

“They can­not sur­vive in areas with­out ade­quate under­story, but they are also threat­ened in seem­ingly suit­able forests when there is too much human activity.”

Suma­tran tigers ‚the small­est sur­viv­ing tiger sub­species, are extremely elu­sive and may live at den­si­ties as low as one cat per 40 square miles. This is the first study to com­pare the den­sity of Suma­tran tigers across var­i­ous for­est types, includ­ing the pre­vi­ously unstud­ied peat land. The research applied spa­tial esti­ma­tion tech­niques to pro­vide bet­ter accu­racy of tiger den­sity than pre­vi­ous studies.

WWF cam­era traps recorded 12 tigers in just two months (2011) in the cen­tral Suma­tran land­scape of Bukit Tiga­pu­luh, includ­ing the moth­ers and cubs in this video. The forests where these tigers live face the loom­ing threat of being cleared by the pulp and paper industry:

Sunarto — a native of Indone­sia, where peo­ple typ­i­cally have one name — col­lab­o­rated on the paper with Mar­cella Kelly, asso­ciate pro­fes­sor of wildlife in the Col­lege of Nat­ural Resources and Envi­ron­ment, Erin Poor of East Lans­ing, Mich., a doc­toral stu­dent study­ing wildlife sci­ence and geospa­tial envi­ron­men­tal analy­sis in the col­lege, Pro­fes­sor Emer­i­tus Michael Vaughan, and Sybille Klen­zen­dorf, man­ag­ing direc­tor of WWF’s Species Con­ser­va­tion Pro­gram, who earned her master’s and doc­tor­ate degrees in wildlife sci­ence from Vir­ginia Tech. The WWF field team col­lected data in part­ner­ship with the Indone­sian Min­istry of Forestry staff.

“Get­ting evi­dence of the tigers’ pres­ence was dif­fi­cult,” Kelly said. “It took an aver­age of 590 days for cam­era traps to get an image of each indi­vid­ual tiger recorded.”

“We believe the low detec­tion of tigers in the study area of cen­tral Suma­tra was a result of the high level of human activ­ity — farm­ing, hunt­ing, trap­ping, and gath­er­ing of for­est prod­ucts,” Sunarto said. “We found a low pop­u­la­tion of tigers in these areas, even when there was an abun­dance of prey animals.”

Legal pro­tec­tion of an area, fol­lowed by inten­sive man­age­ment, can reduce the level of human dis­tur­bance and facil­i­tate the recov­ery of the habi­tat and as well as tiger num­bers. The researchers doc­u­mented a poten­tially sta­ble tiger pop­u­la­tion in the study region’s Tesso Nilo Park, where legal efforts are in place to dis­cour­age destruc­tive human activities.

The above news item is reprinted from mate­ri­als avail­able at Vir­ginia Tech. Orig­i­nal text may be edited for con­tent and length.
(Source: Vir­ginia Tech news release, 27.06.2013)