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Satel­lite analy­sis reveals tiger habi­tats are more intact than expected; area large enough to dou­ble wild tiger pop­u­la­tion remains

Enough forested habi­tat remains to bring the tiger back from the brink of extinc­tion, accord­ing to new analy­sis pub­lished in Sci­ence Advances on 1 April by researchers at the Uni­ver­sity of Min­nesota, RESOLVE, Smith­son­ian Con­ser­va­tion Biol­ogy Insti­tute, Rain­for­est Alliance, Stan­ford Uni­ver­sity and World Resources Insti­tute (WRI). The study found for­est loss was lower than expected in tiger habi­tats, sug­gest­ing there is more than enough habi­tat remain­ing to achieve the inter­na­tional com­mit­ment of dou­bling the wild tiger pop­u­la­tion by 2022 (an ini­tia­tive known as “Tx2”) with addi­tional con­ser­va­tion investment.

Tigers need large areas to sur­vive but pop­u­la­tions can rebound quickly when habi­tat and prey are abun­dant and hunt­ing is con­trolled. For exam­ple, Nepal and India have reported 61 and 31 per­cent increases in their tiger pop­u­la­tions, respec­tively. This is partly thanks to con­ser­va­tion ini­tia­tives like the preser­va­tion of the cross-​boundary Terai Arc Land­scape. Reach­ing the Tx2 goal will require that any sig­nif­i­cant future tiger habi­tat loss is pre­vented, key cor­ri­dors are restored between remain­ing for­est frag­ments, nations imple­ment green infra­struc­ture to pre­vent habi­tat frag­men­ta­tion, and con­ser­va­tion man­agers translo­cate and rein­tro­duce tiger pop­u­la­tions where necessary.

Study results
The study, “Track­ing changes and pre­vent­ing loss in crit­i­cal tiger habi­tat” — uses high and medium-​resolution satel­lite data from Global For­est Watch to exam­ine impact of for­est loss on tiger pop­u­la­tions. It shows that less than 8 per­cent (nearly 79,000 km² or 30,000 mi²) of global forested habi­tat was lost from 2001 – 2014. Though still a loss, this rate of for­est loss is lower than antic­i­pated, given that tiger habi­tats are gen­er­ally dis­trib­uted in fast-​growing rural economies, some with high pop­u­la­tion den­si­ties and fac­ing severe pres­sures from indus­trial agriculture.

“It is not a sign that we are in the clear yet, but it does show us that tigers can poten­tially recover from the edge of extinc­tion if we make the right for­est man­age­ment choices,” added Joshi. “We are see­ing this already in areas like the bor­der between Nepal and India, where for­est cover is recov­er­ing with the help of com­mu­ni­ties and tigers are com­ing back in a big way. ”

Despite lower-​than-​expected lev­els of for­est loss within tiger habi­tat, the study also con­firms the pre­car­i­ous­ness of the species’ sur­vival. The researchers esti­mate that for­est clear­ing since 2001 resulted in the loss of habi­tat that could have sup­ported an esti­mated 400 tigers. This is poten­tially dev­as­tat­ing, con­sid­er­ing the cur­rent global tiger pop­u­la­tion is fewer than 3,500 indi­vid­u­als. Fur­ther­more, the study did not con­sider the dele­te­ri­ous effects of poach­ing and prey loss within these landscapes.

“After decades of work­ing in tiger con­ser­va­tion, it is great to have some encour­ag­ing news for once,” said Eric Din­er­stein, Direc­tor of the Bio­di­ver­sity and Wildlife Solu­tions Pro­gram at RESOLVE and a Senior Fel­low at WRI. “But ille­gal hunt­ing of both tigers and prey can result in ‘empty forests’ with­out enough food or shel­ter to sup­port large preda­tors like tigers. Mea­sur­ing and com­bat­ting this sort of for­est impov­er­ish­ment and its effects will be essen­tial. It com­ple­ments our efforts to iden­tify habi­tat poach­ing in this study.”

Palm oil devel­op­ment biggest threat
The vast major­ity (98 per­cent) of tiger for­est habi­tat loss occurred within just 10 land­scapes, often dri­ven by the con­ver­sion of nat­ural for­est to plan­ta­tions for agri­cul­tural com­modi­ties such as palm oil. The land­scapes with the high­est per­cent­age of for­est clear­ing were in areas of Malaysia and Indone­sia with heavy oil palm devel­op­ment, such as the Bukit Tiga­pu­luh ecosys­tem in Suma­tra, which has lost more than two-​thirds (67 per­cent) of its for­est since 2001, resulted in a loss of habi­tat suf­fi­cient to sup­port an esti­mated 51 tigers. Palm oil devel­op­ment remains an ongo­ing threat— in Indone­sia alone, more than 4,000 km² (1,544 mi²) of for­est habi­tat, an area five times the size of New York City, have been allo­cated for oil palm concessions.

Mon­i­tor­ing tree cover change
This is the first major study to exam­ine tree cover change sys­tem­i­cally across all 76 Tiger Con­ser­va­tion Land­scapes using high and medium res­o­lu­tion satel­lite data. Global For­est Watch and Google Earth Engine, along with analy­sis from the Uni­ver­sity of Mary­land, pro­vided the for­est change data for long-​term analy­sis. Global For­est Watch pro­vides monthly and in some cases weekly tree cover loss alerts that can empower park rangers and com­mu­ni­ties to mon­i­tor and pro­tect tiger for­est habi­tat, even at the finest scale of a sin­gle for­est cor­ri­dor used by a dis­pers­ing male tiger.

“The abil­ity to mea­sure for­est change within endan­gered species habi­tat across the globe is a huge step for­ward for con­ser­va­tion and remote sens­ing,” said Crys­tal Davis, Direc­tor of Global For­est Watch at WRI. “Now it is time to use the data to take action. If we can use that infor­ma­tion to respond faster to threats, we can ensure that tigers will sur­vive for future generations.”

A screen­shot of the inter­ac­tive map at the Global For­est Watch website

You can explore the maps of tiger habi­tat and tree cover change online at glob​al​forest​watch​.org here.

(Source: World Resources Insti­tute press release, 01.04.2016)