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201617Apr20:28

State­ment of con­cern by tiger biol­o­gists on recent rise in tiger numbers

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pub­lished 17 April 2016 | mod­i­fied 18 April 2016
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Tigers TX2 image credit: Souvik KunduThe fol­low­ing state­ment was released on 15 April con­cern­ing the sta­tus of tigers.

On Sun­day, April 10th, the World Wildlife Fund (WWF) and Global Tiger Forum (GTF) issued a report stat­ing that the world’s wild tiger pop­u­la­tion was on the rise, and on track for a dou­bling in a decade (see also here). We do not find this report1 and its impli­ca­tions sci­en­tif­i­cally convincing.

{jb_orangedisc}1.{/jb_orangedisc} Hav­ing devoted years of our lives to try­ing to under­stand and save wild tigers, we believe their con­ser­va­tion should be guided by the best pos­si­ble sci­ence. Using flawed sur­vey method­olo­gies can lead to incor­rect con­clu­sions, an illu­sion of suc­cess, and slack­en­ing of con­ser­va­tion efforts, when in real­ity grave con­cern is called for. Gloss­ing over seri­ous method­olog­i­cal flaws, or weak and incom­plete data to gen­er­ate feel-​good ‘news’ is a dis­ser­vice to con­ser­va­tion, because tigers now occupy only 7% of their his­toric range2. A recent World Con­ser­va­tion Union (IUCN) assess­ment3 showed 40% habi­tat loss in the last decade, and a spike in poach­ing pres­sure in many regions. Cam­bo­dia, Viet­nam, Lao PDR and China have vir­tu­ally lost viable tiger pop­u­la­tions in recent years. This is not a time for con­ser­va­tion­ists to take their eyes off the ball and pat each other on the back.

{jb_orangedisc}2.{/jb_orangedisc} There is no doubt that wildlife man­agers in parts of India and even in spe­cific reserves in South East Asia and Rus­sia have made com­mend­able con­ser­va­tion efforts, lead­ing to recov­er­ies in spe­cific tiger pop­u­la­tions. India has invested mas­sively in recov­er­ing sev­eral tiger pop­u­la­tions2 over the last four decades. This has been pos­si­ble because of strong polit­i­cal, admin­is­tra­tive and pub­lic sup­port rarely matched any­where else.3.

{jb_orangedisc}3.{/jb_orangedisc} Such spo­radic tiger recov­er­ies should be mon­i­tored using sta­tis­ti­cally robust cam­era trap or DNA sur­veys. Rig­or­ous sci­en­tific stud­ies in India, Thai­land and Rus­sia46 demon­strate this can indeed be done. But these stud­ies also indi­cate that tiger recov­ery rates are slow and not likely to attain lev­els nec­es­sary for the dou­bling of wild tiger num­bers within a decade46.

{jb_orangedisc}4.{/jb_orangedisc} Esti­mates of tiger num­bers for large land­scapes, regions and coun­tries cur­rently in vogue in the global media for a num­ber of coun­tries are largely derived from weak method­olo­gies79. They are some­times based on extrap­o­la­tions from tiger spoor (tracks and drop­pings) sur­veys, or spoor sur­veys alone. While spoor sur­veys can be use­ful for know­ing where tigers occur, they are not use­ful for reli­ably count­ing their num­bers. Trans­lat­ing spoor counts to tiger num­bers poses sev­eral sta­tis­ti­cal prob­lems that remain unre­solved9, which can lead to fun­da­men­tally flawed claims of changes in tiger num­bers79.

{jb_orangedisc}5.{/jb_orangedisc} Source pop­u­la­tions of tigers that occur at high den­si­ties and which are likely to pro­duce ‘sur­plus’ ani­mals that can dis­perse and expand pop­u­la­tions now occupy less than 10% of the remain­ing 1.2 mil­lion square kilo­me­tres of tiger habi­tat2. Almost 70% of wild tigers sur­vive within these source sites. They are recov­er­ing slowly, only in some reserves46 where pro­tec­tion has improved. Out­side these source sites lie vast ‘sink land­scapes’, which are con­tin­u­ing to lose tigers and habi­tat due to hunt­ing as well as rural and devel­op­men­tal pressures.

{jb_orangedisc}6.{/jb_orangedisc} With the above con­sid­er­a­tions in view, even tak­ing these puta­tive tiger num­bers at face value, sim­ple cal­cu­la­tions show that dou­bling of the world’s tigers in ten years as hoped for in the report1 is not a real­is­tic propo­si­tion. Assum­ing 7090% of wild tigers are in source pop­u­la­tions with slow growth46, such an antic­i­pated dou­bling of global tiger num­bers would demand an increase between 364831% in these sink land­scapes. We believe this to be an unlikely scenario.

{jb_orangedisc}7.{/jb_orangedisc} Rather than engag­ing in these tiger num­ber games that dis­tract them from real­ity, con­ser­va­tion­ists must now focus on enhanc­ing and expand­ing recov­ery and mon­i­tor­ing of source pop­u­la­tions, while pro­tect­ing their remain­ing habi­tat and their link­ages, all the while being guided by the best of science.

As stated by:

K. Ullas Karanth, Ph.D
Direc­tor for Sci­ence Asia-​Wildlife Con­ser­va­tion Society

Dale Miquelle, Ph.D.
Direc­tor, Rus­sia Program-​Wildlife Con­ser­va­tion Society

John Goodrich, Ph.D.
Senior Direc­tor, Tiger Program-​Panthera

Arjun Gopalaswamy, Ph.D.
Research Asso­ciate, Zool­ogy,
Uni­ver­sity of Oxford, UK

Cita­tions

1 WWF. Global wild tiger pop­u­la­tion increases, but still a long way to go. 2016. Avail­able: http://​wwf​.panda​.org/​w​w​f​_​n​e​w​s​/​?​u​N​e​w​s​I​D​=​265197

2 Wal­ston J, Robin­son JG, Ben­nett EL, Bre­it­en­moser U, da Fon­seca GAB, Goodrich J, et al. Bring­ing the tiger back from the brink — the six per­cent solu­tion. PLoS Biol. 2010;8: e1000485.

3 Goodrich J, Lynam A, Miquelle D, Wibisono H, Kawan­ishi K, Pat­tanav­i­bool A, Htun, S., Tempa, T., Karki, J., Jhala, Y., Karanth, K U.. Pan­thera tigris. The IUCN Red List of Threat­ened Species 2015: e.T15955A50659951. 2015. Avail­able: http://​dx​.doi​.org/​10​.​2305​/​I​U​C​N​.​U​K​.​20152.RLTS.T15955A50659951.en

4 Karanth KU, Nichols JD, Kumar NS, Hines JE. Assess­ing tiger pop­u­la­tion dynam­ics using pho­to­graphic capture-​recapture sam­pling. Ecol­ogy. 2006;87: 29252937.

5 Duangchantrasiri S, Umpon­jan M, Sim­charoen S, Pat­tanav­i­bool A, Chai­wat­tana S, Maneerat S, et al. Dynam­ics of a low-​density tiger pop­u­la­tion in South­east Asia in the con­text of improved law enforce­ment. Con­serv Biol. 2016; doi:10.1111/cobi.12655

6 Miquelle DG, Smirnov EN, Zaumyslova OY, Souty­rina S V, John­son DH. Pop­u­la­tion dynam­ics of Amur tiger (P. t. altaica, Tem­minck 1884) in Sikhote-​Alin Zapoved­nik: 19662012. Integr Zool. 2015;10: 315328.

7 Karanth KU, Nichols JD, Sei­den­sticker J, Din­er­stein E, Smith JLD, McDou­gal C, Johhns­ingh, AJT, Chun­dawat, R, Tha­par, V. Sci­ence defi­ciency in con­ser­va­tion prac­tice: The mon­i­tor­ing of tiger pop­u­la­tions in India. Anim Con­serv. 2003;6: 141146.

8 Karanth KU. India’s Tiger Counts: The Long March to Reli­able Sci­ence. Econ Polit Weekly. 2011;XLVI: 2225.

9 Gopalaswamy AM, Delam­pady M, Karanth KU, Kumar NS, Mac­don­ald DW. An exam­i­na­tion of index-​calibration exper­i­ments: count­ing tigers at macro­e­co­log­i­cal scales. Yoc­coz N, edi­tor. Meth­ods Ecol Evol. 2015;6: 10551066. doi:10.1111/2041-210X.12351

{jb_warning}This makes you won­der how impor­tant it is for WWF and GTF to show the world a suc­cess. Espe­cially when the sci­ence where­upon this suc­cess story is based shows flaws and there­fore not backs up the story. Com­ing from these renown tiger researchers and con­ser­va­tion­ists their state­ment should be taken seri­ously I would say [Moos].{/jb_warning}


(Source: WCS press release, 15.04.2016)


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Tiger range countries map

Tiger map” (CC BY 2.5) by Sander­son et al., 2006.

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