Active Intervention and Conservation: Africa's Pachyderm Problem

Active Intervention and Conservation: Africa's Pachyderm Problem Author(s): Joel Berger and Carol Cunningham Reviewed work(s): Source: Science, New Series, Vol. 263, No. 5151 (Mar. 4, 1994), pp. 1241-1242 Published by: American Association for the Advancement of Science Stable URL: http://www.jstor.org/stable/2883460 .

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enforced by paramilitaryunits, has not workeddespitethe deathsof morethan 150 poachers and numerousrangers (5). Not unexpectedly, failures stem from inadequatefundingand, in countrieslike Ethiopia, Sudan, Uganda, Angola, and MozamJoel Berger and Carol Cunningham bique, politicalinstability(6).

Given the inadequaciesof protective legislation and enforcement, Namibia, Since 1900 the world'spopulationhas Economicand political interventionfacili- Zimbabwe,and Swazilandare using a conincreasedfromabout 1.6 to over 5 billion; tated recovery. The sale of ivory was troversialpreemptivemeasure, dehorming the U.S. populationhas kept pace, growing bannedat the 1989 Conventionof Interna- (Fig. 1), with the hope that complete detional Trade in Endangered Species valuation will buy time for implementing from nearly 75 to 260 million. While the expansion of humans and environmental (CITES)meeting, althoughthe resultwas other protectivemeasures(7). In Namibia alterations go hand in hand, it remains muchdissensionbetweenAfricancountries. and Zimbabwe, two species, black and uncertain whether conservationprograms Those countrieswith abun t elephants white rhinos. (Ceratodhriunsimnum),are will slow our biotic losses. Currentstrate- supportedcontinued utilizationto pay for dehorned,a tactic resultingin sociological gies focus on solutionsto problemsassoci- conservationprograms;those with dwin- and biologicaluncertainty:Is poachingdeated with diminishingand less continuous dling populationssupportedthe ban. Ele- terred?Can homless mothersdefendcalves habitats,but in the past, when habitatloss phantpopulationsdeclinedfromover 1 mil- fromdangerouspredators?

On the basis of our work in Namibia was not the issue, active interventionpre- lion to less than half that beforethe CITES vented extirpation.Herewe brieflysumma- decisionwasreached,andthe banis credited duringthe last 3 years(8) and comparative informationfromZimbabwe,some dataare for today'sreboundingpopulations(3). rize intervention measuresand focus on Neither conventionalnor radicalinter- available.Horns regeneraterapidly,about tactics for specieswith economicallyvaluable body parts, particularlyon the merits ventive measuresarehelpingAfrica'sblack 8.7 cm per animalper year, so that 1 year and pitfallsof biologicalstrategiestriedfor rhinos (Dicerosbornis) (4). CITESenact- after dehoming the regrownmass exceeds Africa'smost endangeredpachyderms,rhi- ed protectivelegislation 18 yearsago, but 0.5 kg. Becausepoachersapparentlydo not noceroses. populationshave plummeted;in 25 years, preferanimalswith moremassivehorns(8), Rescueefforts,this centuryand last, are 65,000 rhinos were reduced to less than frequentand costly hom removalmay be credited with preserving two ungulates, 2,500, a loss of 97%. Prohibitionsagainst required(9). In Zimbabwe,a populationof Przewalskihorses (Eqs przewalskii)and the hom trade have been so ineffective 100 white rhinos, with at least 80 dePere David's deer (Elaphurusdaviiensus), that, in all of Africa today, only one un- homed, was reducedto less than 5 animals both currentlyextinct in the wild but sur- fenced population numberingmore than in 18 months (10). These discouraging 100 animals exists-that in the northem resultssuggestthat interventionby itself is viving in smallcaptivepopulations.Active interventionis most common today when Naniib Desert of Namibia. Like intema- unlikely to eliminate the incentive for other tacticsfail. The handfulof remaining tional legislation, national protective de- poaching. Nevertheless, some benefits acblack-footedferrets (Mustelanripes) and crees have done little. Even Zimbabwe's crue when govemments, rather than California condors (Gymngyps caifor- hard-line shoot-to-kill (poacher) policy, poachers, practice hom harvesting,since less horn entersthe blackmarket.Whether ruanus)wereseizedfromthe wild, propagathorn stockpiles may be used to enhance ed in captivity,andthen returnedto former conservation remains controversial, but ranges;whetherthese populationswill permortalityrisks associatedwith anesthesia sist is unclear. duringdehoming are low (5).

Fewmeasureshave effectivelyhaltedthe Biologically,there have also been probillegal killing of species for lucrativebody lems. Despitemediaattentionand a bevyof parts. just as last century'sbison (Bison allegationsabout the soundnessof dehombison)were shot for tonguesand hides, the ing (11), serious attempts to determine presentvictims include tigers (Panheratiwhether dehoming is harmfulhave been gris),bears(Ursusspp.), andrhinos.Jimbu, remiss.A lack of negative effectshas-been the consumption of specialid animal suggestedbecause(i) homed and dehomed parts, as well as the use of rhino horn in individualshave interactedwithout subsetraditionalAsian medicinesand in the jamquent injury; (ii) dehomed animals have biyyas (dagger handles) of Yemeni men |~~~ ~ thwartedthe advance of dangerouspredahave precipitatedthe declines.Interventive tors; (iii) feeding is normal;and (iv) desolutionshave had their place. When few homed mothers have given birth (12). plainsbison remained,an 1880sSmithsonHowever, most claims are anecdotal and ian expedition captureda small group in mean little without attendantdata on deMontana, bred them on the East Coast, mographiceffects.Forinstance,while some and laterreestablishedancillarypopulations dehomedfemalesgive birth, it maybe that in South Dakota and Oklahoma (1). But these femaleswere pregnantwhen firstimwhat has workedfor one specieshas not for mobilized. Perhapsothers have not conanother. In 1988, an Africanelephantwas ceivedor have lost calvesafterbirth. Withkilled for its ivory every 8 minutes (2). out knowingmore about the frequencyof J. Bergeris in the Ecology, Evolution,and Conservamortality,it seemsprematureto arguethat tion Biology Programand C. Cunninghamis in the dehorningis effective.

Fig. 1I A black rhino being dehomed in the and ResourceSciences of Environmental DeparTment We gathered data on more than 40 northernNamnib Desert in 1991. at the Universityof Nevada, Reno, NV89512, USA.

Active

and Intervention Pachyderm Africa's

Conservation: Problem

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knownhomed and homless blackrhinosin the presenceand absenceof dangerouscarnivoresin a 7,000 km2areaof the northem NamibDesertand on 60 homed animalsin the 22,000 km2EtoshaNational Park.On the basisof over 200 witnessedinteractions betweenhomed rhinos and spottedhyenas (Crocutacrocuta)and lions (Pantheraleo), we saw no cases of predation, although motherschargedpredatorsin about45%of the cases. Seriousinterspecificaggressionis not uncommon elsewhere in Africa, and calves missing ears and tails have been observedfrom South Africa,-Kenya, Tanzania, and Namibia (13).

To evaluate the vulnerability of dehomed rhinos to potential predators,we developed an experimental design using three regions:Area A had homed animals with spotted hyenas and occasional lions, areaB had dehomed animalslacking dangerouspredators,and area C consisted of dehomed animalsthat were sympatricwith hyenasonly. Populationswere discreteand inhabitedsimilarxeric landscapesthat averagedless than 125 mm of precipitation annually.AreaA occurrednorthof a country-longveterinarycordon fence, whereas animalsfromareasB and C occurredto the south or east, and no individualsmoved between regions. The differencesin calf survivorshipwere remarkable.All three calvesin areaC died within 1 yearof birth, whereas all calves survived for both dehomed females living without dangerous predators(areaB; n = 3) and for homed mothersin areaA (n = 4). Despite admittedly restrictedsamples,the differencesare striking [Fisher's(3 x 2) exact test, P = 0.017; area B versusC, P = 0.05; area A versusC, P = 0.029]. The data offera first assessmentof an empiricallyderived relation betweenhoms and recruitment.

Our resultsimply that hyena predation was responsiblefor calf deaths, but other explanationsare possible.If droughtaffected one area to a larger extent than the others, then calves might be more susceptible to early mortality. This possibility appears unlikely because all of westem Namibia has been experiencing drought and, on average, the desert rhinos in one area were in no poorer bodily condition than those in another. Also, the mothers

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who lost calveswerebetween 15 to 25 years old, suggestingthat they werenot firsttime, inexperiencedmothers (14). What seems more likely is that the drought-induced migrationof more than 85% of the large herbivorebiomass(kudu,springbok,zebra, gemsbok, giraffe, and ostrich) resultedin hyenaspreyingon an alternativefood, rhino neonates, when motherswith regenerating horns could not protect them.

Clearly,unpredictableevents, including drought,maynot be anticipatedon a shorttermbasis.Similarly,it maynot be possible to predictwhen governmentscan no longer fund antipoachingmeasures,an event that mayhave led to the collapseof Zimbabwe's dehornedwhite rhinos. Nevertheless, any effectiveconservationactionsmustaccount for uncertainty.In the case of dehoming, additionalprecautionsmust be taken.

Froman interventionistperspective,the tactic that seemsto workbest has been the transferof animalsto small, guardedsanctuaries. In Kenya, the 1990s have seen births finally exceed deaths (15). Population recoveryhas been progressingfor more than 30 years in South Africa with the successfulestablishmentof numeroussatellite populations (4). Nevertheless, problems involvinghornsstill exist. Fight-related mortalityin both sexes is uncharacteristicallyhigh in black rhinos. If interventive managementis to improvein situ recovery, two tactics might help-removal of both hyenas and horns. Dehorning should reduce female fight-relatedmortality,which may account for up to 30% of adult and subadultfemaledeaths (14) once sanctuary populations are safe from poachers. But where the aim is to improve population viability by juvenile recruitment,dehorning appearsimprudentunlessdangerouscarnivores are removed. Once the interventionist trackbegins, an increasingcascade of distastefulecosystemmanipulationswill become inevitable.

It may never be possible to develop a truly comprehensiveframeworkof proactive managementacrossspecies, but translocation to protectedareashas provedsuccessfulforArabianoryx (Oryxleucoryx)and North Americanbison, and it may be the last recoursefor Africa'stwo rhino species.

Many biologistswould claim that diffusing

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the risk of failureby the establishmentof satellite groupsis modem conservationat its best. As early as 1906, Homadaybelieved in interventive management:"to provideagainstlocal failures,and possible outbreaksof contagiousdisease, it seems desirablethat . . . severalherdsshouldbe establishedin widely separatedlocalities" (16). What we still don't know is how widely this tactic shouldbe applied;we do know that forblackrhinosit mustbe soon.

REFERENCESAND NOTES 1. J. Berger and C. Cunningham, Bison: Mating and Conservation in Small Populations (Columbia Univ. Press, New York, 1994).

2. W. Conway, Wildl. Conserv. 96, 2 (1993).

3. I. Douglas-Hamilton and 0. Douglas-Hamilton.

Battle for the Elephants (Doubleday, Ontario, 1992).

4. 0. A. Ryder, Ed., Rhinoceros Biology and Conservation (Zoological Society of San Diego, San Diego, 1993).

5. M. Kock and M. Atkinson, "Report on dehorning of black and white rhinoceroses in Zimbabwe" (Zimbabwe Department of National Parks and Wildlife Management, Harare, 1993).

6. N. Leader-Williams and S. D. Alborn,Nature 336, 533 (1988).

7. M. Lindeque, S. Afr. J. Sci. 86, 226 (1990).

8. J. Berger, Nature 361, 121 (1993); Afr. J. Ecol. 31, 261 (1993); _ C. Cunningham, A. Gawuseb, M. Undeque, Conserv. Biol. 7,920 (1993); J. Berger and C. Cunningham, Behav. Ecol., in press.

9. E. J. Milner-Gulland, N. Leader-Williams, J. R. Beddington, Pachyderm, in press.

10. J. Rachlow, "Conservation of rhinos in Zimbabwe: Effects of horn removal. Progress report" (Zimbabwe Department of National Parks and Wildlife Management, Harare, 1993).

11. C. van der Merwe, Leadership 5, 84 (1989); C. Tudge, New Sci. 132, 34 (5 October 1991); D. Bartlett and J. Bartlett, Natl. Geogr. Mag. 181, 55 (1992); Anon., Buzzworm 5, 34 (1993).

12. T. Milliken,K. Nowell, J. B. Thomsen, The Decline of the Black Rhino in Zimbabwe (TRAFFICInternational, Cambridge, 1993).

13. P. A. Hitchins, Pachyderm 7, 8 (1986); J. Goddard, E Afr. J. Ecol. 5, 133 (1969).

14. J. Berger and C. Cunningham, in preparation.

15. R. A. Brett, Pachyderm 13, 31 (1990).

16. W. T. Hornaday, quote from 1906 letter in Archives of the American Bison Society, New York Zoological Society (NYZS), Bronx.

17. We thank the American Philosophical Society; Hasselblad Foundation; FrankfurtZoological Society; NYZS-The Wildlife Conservation Society; World Wildlife Foundation; National Science Foundation; U.S. Agency for International Development; University of Nevada; Rhino Rescue; the Namibian Ministry of Wildlife, Conservation, and Tourism; VirginAtlantic Air;South African Airways; D. Bolze, P. Erb, A. Gawuseb, M. Kock, E. Joubert, M. Lindeque, R. Loutit, B. Loutit, G. Owen-Smith, J. Rachlow, and G. White.