ANDUNCERTAINTIES
REGARDING
TRENDSIN
IRONIES,
MISCONCEPTIONS,
BEARPOPULATIONS
INVITED PAPER
MinnesotaDepartmentof NaturalResources, 1201 East Highway2, GrandRapids,MN55744, USA,email:
DAVIDL.GARSHELIS,
[email protected]
Abstract: Despite our rapidly increasingknowledge of bears, there are few places in the world where we really know how bear populationsare
faring. I arguethat bear conservationwould benefit by highlightingratherthanhiding this uncertainty.Assessments of bearpopulationsoften are
based on recordsof dead animalsandtrendsin habitatavailability.These dataproducedubiousindicationsof populationtrend. Case studiesrelating
to the tradein bearparts,sportharvests,and nuisancekills indicatethatrecordsof human-killedbearsmay not be accurateand may not necessarily
reflect changes in populationsize. Increasingbear populationsmay continue to rise with increasedlevels of humanexploitation(as long as it is
below the maximumsustainabletake), whereasdeclining populationsmay continueto plummetdespite reducedexploitation. Similarly,whereas
loss of habitat(forest area)probablyengendersa decline (of unknownmagnitude)in bearpopulations,unchangingor increasingforestedareamay
not necessarilyresultin stableor increasingbearnumbers. Ironically,bearpopulationsthathave been managedfor sustainedharvestshave generally
fared betterthan populationsin which huntinghas been prohibited,mainly because the formerbettercontrols illicit huntingthan the latter. Longtermconservationof bearsrequiresbetterinformationon populationtrends,butbettertechniquesareunlikelyto be developed if faults andinadequacies of currentdata are not clearly recognized.
Ursus 13:321-334 (2002)
Keywords: Asia, bears,conservation,habitatloss, harvest,NorthAmerica,poaching,populationsize, populationtrend,tradein bearparts, uncertainty
In most human societies, knowledge empowers,
whereas uncertainty signifies fallibility, timidity, and
weakness. Scientistsarepresumedto be knowledgeable,
andthusable to produceaccuratefacts, explanations,and
predictions;those thatdo so with certaintytendto be held
in high esteem by the public. The soothsayersof the past
were probablywrong more often than are modem forecastersof environmentalandastronomicalevents,buteven
today's complicatedcomputermodels are prone to error
because we lack a full understandingof most naturalsystems.
A majorconcern in today's world is the threatof species extinctions due to the activities of humans. Thereis
a strongrelationshipbetween humanpopulationsize and
threat of extinction of native fauna (McKinney 2001).
Although we recognize the basic causes of extinction
(Diamond 1989) and we have been able to identify taxa,
ecosystems, and geographicareas that are most susceptible to extinctions(Cole et al. 1994, Mace andBalmford
2000), ecologists and conservationbiologists have been
strugglingto understandhow to relieve species from extinctionthreats.Seeminglybasicquestions,suchas "What
is the minimumviable populationsize and what level of
human exploitation is sustainable? What habitatsdoes
the species require and how much area should be protected within reserves?"are routinely debated, because
empiricaldataare lacking. Unfortunately,the science of
ecology is by natureinexact and laden with uncertainty.
Shrader-Frechette
andMcCoy (1993:123-124) contend
that due to the inherentcomplexity of ecology, there are
few governing principles, so case studies are the best
means for achieving understanding.The methodof case
studiesinvolves scrutinizingthe detailsof particularsituations in an attemptto "makesense" of them. Accumulating and comparingresultsfrom a series of relatedcase
studies advancesthe science.
For large mammals such as bears, experimentationis
rarelyemployed as a partof the case study. Instead,bear
biologists tend to reachconclusions based on patternsin
the data, logic, insight, and knowledge of other studies.
Case studies generallyenterthe body of science through
a process of peer-review,althoughmuch informationis
containedin less formalreportsand even raw data.
At periodicjuncturesit is worthwhileto review the basis of conclusions and direction of thinking. In experimentalsciences,predictionsthatarenotupheldempirically
areultimatelydiscarded. In sciences based on case studies, apparentanomaliesmay representtrulyuniquesituations, making it difficult to tease out erroneous
information. Nevertheless, occasional re-examinations
may prove to be fruitful- if not to correctthe past, to
guide the future- especially in termsof species conservation.
In this paperI drawattentionto severalmisconceptions
relatedto the monitoringand conservationof bearpopulations. I rely heavily on case studies to illustrate my
points. These are used mainly as counter-examplesto
prevailingviews or to exemplify common problems.
A principalpurposeof this critiqueis to highlight the
uncertainty,andhence fallibility,of our understandingof
bearpopulations.Therearefew places in the worldwhere
biologists would admit to not knowing whether a bear
populationwas increasing,decreasing,or stable, yet the
realityis thattherearefew placeswherewe reallydo know
322
Ursus 13:2002
for surehow bearsare faring. Seemingly contraryto my
openingremarks,I believe thatultimatelywe, as bearbiologists benefit - because bears benefit - by critically
examining the basis of our knowledge and admittingto
our foibles anduncertainties.
MISCONCEPTIONS
REGARDING
TREND
POPULATION
TrendAscertainedfromNumbersof Dead
Bears
In a populationof unknown size, a large death toll is
obviously unnerving. Because most bearpopulationsare
of unknownsize, a recordof increasingknown deathsis
often taken as primafacie evidence of a populationdecline. Moreover,even poor recordswith no clear trend
but occasionaldocumentationof a surgeof deathsmay be
cause to fear a populationdecline.
Recordsof bearparts(principallygall bladders)traded
amongAsian countriesare a salient example of tallies of
deadbearsbeing used to interpretpopulationtrends. Several good investigative reports exposed the broad geographicscopeof thistrade(Mills andServheen1991;Mills
1995; Mills et al. 1995, 1997), althoughit was not possible to accuratelyquantifyit. Some evidence suggested
increases or decreases in bear kills in certain countries,
based on documentedor estimatednumbersof exported
or importedparts.However,populationtrendassessments
based on trendsin the tradein bearparts,andhence numbers of bearskilled, have been inconsistent. Considerthe
cases of 3 countriesthat have been heavily involved in
this trade.
China.-In China,the killing of bears(otherthangiant
pandas[Ailuropodamelanoleuca])for theirpartswas legal until 1989. In the decade preceding this restriction
(1979-88), several thousandbear gall bladderswere exportedfromChinato Japan(Servheen1990). Additional,
but smaller numbersof gall bladderswere exported to
South Korea (Mills et al. 1995). However, trends and
quantitiesof bearskilled for the tradein gall bladdersare
nearlyimpossible to discernfrombile exportdata,due to
manyconfoundingissues, includingtradein fake bearbile
(gall from animals other than bears that are claimed as
bears) and farmed bile (bile drainedfrom live, captive
bears)(Box 1).
Farmingbears for their bile began in China in 1984.
During 1985-89 hundredsor thousandsof bearswere removed from the wild to stock captive populations(Fan
and Song 1997). However, since 1989, all of the species
of bears in China (brown [Ursus arctos], Asiatic black
[U. thibetanus],andsun[Helarctosmalayanus])havebeen
protected,inasmuchas killing or capturingis illegal with-
out a special permit,and selling of partsof wild bearsis
also prohibited(Mills and Servheen 1991, Fan and Song
1997). Has this supposedchangein exploitationof bears
enabledbearpopulationsto increase? The answeris unclear.
Santiapillaiand Santiapillai(1997:23) indicated that
China,bearpopulationsarein decline."They
"throughout
cite an estimate of 15,000-20,000 Asiatic black bears in
China, which matches the range reportedby Ma and Li
(1999), based on "1994 statistics". Ma andLi (1999) believed that over-huntingfor bear parts was causing this
species to decline, althoughtheir chief evidence for recentdeclineswerediminishingnumbersof purchasedbear
skins during1986-1991. Cheng (1999:123), referringto
these same data, concludedthat "In recent years, ... the
numberof bears [bothblack andbrown,in one province]
has droppedsignificantly..." Li et al. (1996; citing Ma et
al. [1994]),presentedhigherpopulationestimates(20,00032,000 Asiatic black bears and 12,000-14,000 brown
bears), but also suggested that populationswere shrinking. Fan and Song (1997:11) called these estimates "an
emotional guess" and presentedtheir own estimates of
46,500 Asiatic black bears, 14,800 brownbears,and400
sun bears,based on field surveys and interviewswith local people. They claimed thatafterbears were protected
in 1989,populationsincreased.Ma et al. (2001) conducted
a more recent survey, also based on field sign and local
interviews,and concludedthat Asiatic black bearsnumbered <20,000 and were still declining numericallyand
geographically. Differences in these opinions appearto
be just that- beliefs lacking much factualbasis.
Russia.-Exportation of bear gall bladdersincreased
dramaticallyin Russia in the early 1990s for variouspolitical and economic reasons (Chestin 1998). Chestin
(1998) believed that because of increasedeconomic incentives, legal harvestsof brownbears,generallytotaling
4,000-4,500 nationwide,mighthave been matchedby an
equalnumberof illegally taken(poached)bears. Imports
of bile to South Korea from Russia showed a sharpincrease in the 1990s, but still representeda small number
of bears killed/year(Box 1). Priorto this rise in poaching, the total numberof Russianbrown bears appearsto
have increased,from an estimatedpopulationof 80,000
in 1981 to 125,000 in 1990, and the geographic range
expandedconcomitantly(Chestin1999). Annualsustainable harvestquotas were establishedso as not to exceed
10% of the population,but in reality appearedto be far
below that. Thus,even if poachingwas as high as posited
by Chestin(1998), the overallrateof humanexploitation
may have been sustainable.Most killing for gall bladders
has occurredin the RussianFarEast (Kamchatka),where
some reports suggested an annual take of 1,500-2,000
brownbears,possibly 20% of the population(Nikolaeno
UNCERTAINTIES
INPOPULATION
TRENDS* Garshelis
323
Box 1. Records of bile imports or exports have been used to estimate the number of bears killed to support that trade.
Tabulatedbelowarethe supposed numbersof bears killed/yearto accountfor importsof bearbile recordedby the Korean
CustomsAdministration
(Mills1995,Millset al. 1995)for 4 countriesof origindiscussed in the text.
Although these numbersseem to indicate clear trends
in bears killed over time, the data are too confoundedto
drawsuch conclusions. Severalmajordifficultiesexist in
convertingbile to bears.
Variationin Gall BladderMass.-The amountof bile
in gall bladdersvaries by species, geographic area, and
time of year, so any conversionof bile mass to dead bear
equivalentsis subjectto appreciableerror. Values tabulated are based on 30 grams/whole,driedbear gall bladder (Lay 2001). Mills (1995) suggestedan averageof 60
grams/gallbladder,but did not presentsupportingdocumentation. Furtheruncertaintyinvolves whetherthe Korean customs records relate to grams of bile, grams of
whole gall bladders,or a combinationof both.
Changes in Regulations,Enforcement,and Recording
ofImports.-Mills (1995) andMills et al. (1995) reported
Korean bile import data by decade, covering 24 years,
1970-93. The Republicof Koreajoined the Convention
on InternationalTrade in EndangeredSpecies of Wild
Faunaand Flora (CITES) in July 1993, and in 1996 acceptedthe AppendixII listing of bearswhose populations
were not consideredthreatened;this listingrequiresdocumentationto ensure legal import. Korea also concomi-
tantly improved surveillance and enforcement. These
actions resulted in better recordingof bear imports and
more seizures, so the total amountof bile rose by nearly
an orderof magnitudefromthe 1990-93 periodshown in
the table to 1994-99 (Mills et al. 1997, Yoon 1997, Sohn
2001).
CounterfeitBile.-Several investigativereports(Lauet
al. 1994, Changet al. 1995, Gaski 1997) indicatedthat a
very high proportionof the presumedbear gall bladders
on the Asian market (94-98%) are from animals other
than bears. This would severely inflate the estimate of
dead bearsbased on bile imports. Tradein non-beargall
bladderslikely explains the unreasonablylarge quantity
of bile from Indonesiaand Japanin the 1970s. It would
be impossible to remove >7,000 bears annually for 10
yearsfroma Japanesepopulationof 10,000-15,000 black
bears(Hazumi1999) and2,000-3,000 brownbears(Moll
2001). Moreover,Japanalso has an internalmarketfor
bear bile, and exports to countriesother than South Korea, so the amountof bile obtainedin Japanis far more
thanindicatedon Koreancustoms records.
Farmed Bile.-Bile obtained from catheterized,captive (farmed)bearsprobablyexplains the sharpincrease
in imports from China in the 1990s. Lau et al. (1994)
indicatedthat virtuallyall the bile importedfrom China
(into Hong Kong) in the early 1990s was from captive
bears, not dead bears. The Korean import data do not
discriminatebetween powdered bile (most likely from
farmedbears)andwhole gall bladders(deadanimals,most
of which are not bears).
1993, cited in Chestin 1999). In this area it is assumed
thatnumbersdeclined,althoughpopulationestimatesfrom
aerialsurveysshowedan equivocaltrend(Revenko1998).
Commercially-motivatedpoaching of Asiatic black
bearsin the RussianFarEast (the only areaof Russia inhabitedby this species) also has increased,but estimates
of populationsize andpresumedratesof declinehavebeen
highly variable and contradictory(Yudin 1993). Moreover,referencesto populationdeclinesin this species generally referto the distantpast. Chestinand Yudin(1999)
suggested that Russian Asiatic black bears numbered
25,000-35,000 at the beginningof the 1800s, only 6,0008,000 in 1970, and4,000-5,000 by 1985, which is thought
to be about the same remainingat present. Until 1983,
Russianslegally harvested300-400 Asiatic black bears/
year. Since then,blackbearhuntinghas been illegal. It is
uncertainwhetherthe previous legal harvestof 300-400
was sustainable(it would seem so if the populationwas
4,000-5,000), and if so, whetherillegal harvestsnow ex-
ceed that. Sustainabilityof the harvestrelatesonly to the
numberof bearskilled, not whetherthey were legally or
illegally taken. Of course the formeris more readily adjusted to remainsustainable,but the lateris not by definition unsustainable.
Japan.-Japan is an importerandexporterof bearbile,
as well as a user of productsobtainedfrom native bears.
Both import and export of bile appearedto decline dramatically from the 1970s to the early 1990s (Mills et al.
1995), althoughthese data are difficult to interpret(Box
1). Harvestingof brownbears (on Hokkaido)and black
bears(on Honshu)is legal, but ratherloosely regulatedin
partbecausetherehas been a long-term,purposefuleffort
to reduce numbersof bears. Hunterscan legally sell all
partsof bearsthey harvest,and thereare no governmentimposed restrictionson the numberthey can take during
the huntingseason. It is believed thatthe opportunityto
sell bearpartsis largely what sustainsinterestin hunting
(Moll 2001).
Calculatednumberof bearskilled/year
Countryof origin
1970s
1980s
China
Russia
Japan
Indonesia
3
0
7100
690
3
0
26
3
1990s
490
15
7
0
324
Ursus 13:2002
Some hunting restrictions were imposed during the
1980s and 1990s (e.g., eliminationof the brownbearseason during spring when hunterscould snow-trackbears
to or from their dens) (Mano 1998, Moll 2001); this reduced the kill, but not in all areas(Kaji and Mano 1996).
Mano and Moll (1999:129) thoughtthatbrownbearharvests still exceededsustainablelimitsin some places, such
as the Oshimapeninsula,threateningthe "long-termpersistence of that subpopulation."In anotherreport,however, Mano (1998:179) indicatedthatthe Oshimabrown
bearpopulation"persistsin high numbers,"but suggested
that bears in more lightly hunted areas were declining.
Aoi (1991:135) described the overall Hokkaido brown
bear population as "declining rapidly," whereas Kaji
(1992:413) thought that "Furtherstudies are needed to
analyze the populationtrend..." It seems clear from the
conflicting reportsthatKaji's call for more study is warranted.
Approximately2,000 Asiatic black bears have been
taken annuallyon Honshu, half by huntingand half explicitly for pest control(Hazumi1994). Based on density
estimatesproducedfrom springtimesnow-tracking,capture-recapture,and habitatassessmentacross the island,
the total populationsize has been estimated at 10,00015,000. The veracityof this estimateis difficultto assess,
and even if it is assumedto be accurate,the span is wide
enoughto precludejudgmentas to whetherpresentlevels
of exploitationare sustainable. Hazumi(1999:209) consideredJapaneseblack bears to be "facing a crisis," due
to the combinedeffects of habitatdegradationanduncontrolledharvesting,but he had no real evidence of a populationdecline. Some prefecturalgovernmentstudieshave
attemptedto assess local populationtrends,but flaws in
theirmethodologyunderminedthe credibilityof theirresults (Huygens and Hayashi2001).
Generalities.-The 3 countrieshighlightedabove were
selected not because they exemplified situationswith inadequatedata on bear populationtrends, but ratherbecause, comparedto otherAsian countriesimpactedby the
gall bladdertrade, they had considerablymore data on
their bear populations. Additionally,unlike most of the
other Asian countries, some records of the gall bladder
tradeexist for these 3, and each of the 3 exhibitedan apparenttemporaltrendin the volume of this trade(Box 1).
Despitethese data,bearpopulationtrendsin these 3 countriesareequivocal,even controversial.The statusof bears
in otherAsian countriesis even more uncertain.
I am not suggesting that the gall bladdertrade is not
cause for grave concern- certainlyit is. But this concern should arise from the uncertainty,not the certainty,
of the impacts. We cannotdiscountthe possibility thatin
many areas,the exploitationof bearsfor partsis sustain-
able. That is, we cannotreject the null hypothesisof no
detrimentaleffect. However,employingstatisticalterminology, we have insufficientpower (due to a paucity of
data)to rejectthishypothesis.Normally,we areconcerned
mainly with type-I errors: we attemptto avoid erroneously rejectinga truenull hypothesis. However,in cases
involving harm,to people or the environment,it may be
ethicallymoreresponsibleto erron the side of cautionby
trying to avert effects that may be nonexistent(i.e., putting moreefforttowardavoidingtype-IIerrors;Mapstone
1995). Shrader-Frechetteand McCoy (1993:153) put it
this way: "incases of uncertainty[my emphasis],ecologists ought to adopt an ethical (ratherthan purely scientific) account of ecological rationality." Thus, for rare
species, the burdenof proof should switch from proving
that a populationdecline has occurred,to proving that it
has not (Taylorand Gerrodette1993).
A problemwith emphasizingthe avoidanceof type-II
errorsin cases of potentialharm,especially irreversible
harmsuch as extirpation,is losing trackof the underlying
uncertainty. It can become all too easy, once accepting
thata detrimentaleffect may exist, to begin to prophesize
the magnitudeof the effect. Withoutreal data, this can
become a game of emotionalguesstimation.In cases such
as the gall bladdertrade, where to most Westernersthe
practice is culturallyalien and repugnant,claims of effects often become exaggerated, especially if they are
thoughtto help instigateremedialaction. Hence, assertions of Asianbearpopulationsbeing "devastated,""decimated",or "depleted"(Knights 1996) tend to be widely
accepted, or at least not questioned. It is doubtfulthat
such unsubstantiatedclaims servethe best interestof bear
conservation. I believe they do not, mainly because they
falsely reflectthe certaintyof ourknowledge. Hence,they
create more opportunityfor furthermisinformation,especially relatedto populationlevel effects of highly visible mortality.
Increasesor decreasesin levels of humanexploitation
may not necessarilyresult in attendantchanges in population size. An increasing populationmay continue to
increasein the face of heightenedexploitation,whereasa
declining populationmay continue to plummet despite
reducedexploitation. The discovery of a massive shipment of gall bladders or a large numberof dead bears
should not, in itself, be construedto representa population decline, and neither should the absence of these be
cause for complacency.
The examplesso farconcernedAsian bearsandthe gall
bladdertrade. Becausethis exploitationis largelyunregulated,it is presumedto be unsustainable.In contrast,recreational (sport) harvests are overseen by management
agencies whose responsibilityis to ensure that they are
IN POPULATION
TRENDS * Garshelis
UNCERTAINTIES
sustainable. Nevertheless,unusuallylarge sportharvests
often raise concerns, if not by the managementagency,
by others interestedin bears. I offer 2 examples dealing
with Americanblack bears (U. americanus).
Tennessee.-The legal harvest of black bears in Tennessee in 1997 was at least twice that of previous years,
due to a naturalfood failurethatpromptedmany bearsto
leave the sanctuaryof the Great Smoky MountainsNational Park. Pelton (1998:26) reportedthatin reactionto
this high harvest,some biologists, bearadvocacygroups,
and alarmistsin the generalpublicclaimedthatthe popuand"drivento extirpation."
lationwas being"slaughtered"
Long-termresearch(Pelton and van Manen 1996), however, showed thatthe populationhad been increasingfor
manyyearsandcontinuedto increaseafterwards.Unfortunately,the body count was obvious, whereas the biological data either were not appreciated or did not
constituteas appealinga story.
Minnesota.-Hunting of black bearsin Minnesotahas,
since 1982, been regulatedby restrictions(quotas)on the
numbersof licenses available. This system was implementedto reducethe rateof harveston whatwas thought
to be a decliningpopulation. Aftera few yearsof sharply
curtailedharvests,therewas ampleevidencethatthepopulation was growing. However,a food failurein 1985 disrupted normal feeding activities, which resulted in an
unusuallylargenumberof bearsbeing killed as nuisances.
This large killing attractedconsiderableattentionby the
news media. Moreover,one bearbiologist, who hadbeen
monitoring a few radiocollaredbears at the time, suggested, in a memo to the managementagency, that the
food failurecaused "severemalnutrition,"possibly leading to reducedreproductionand starvationof cubs. He
also warnedthat2 age classes of young bearsmight have
been "virtuallyeliminated,"thus compoundingthe high
kill (L. Rogers, 1986, unpublishedreport). Based on this
report,an environmentalgroupconcludedthat "it would
be surprisingif the black bearpopulationhas not already
been nearlyeliminated..." (SierraClub,NorthStarChapter, Minneapolis,Minnesota, 1986, unpublishedreport).
Hindsight showed these forecasts to be wrong. Collections of bearteethfrom subsequentharvests,used for age
determination,showedno indicationof weakcohorts.Furthermore,population modeling interfacedwith 2 statewide, mark-recapture
populationestimates(Garshelisand
Visser 1997) indicatedthat the populationgrew steadily
at -5% annually (D. Garshelis,unpublisheddata). Fifteen years after the 1985 "high kill" the populationhad
tripled, and despite steadily increasing harvests, the
agency's goal of stabilizingpopulationsize had not been
achieved. As in the otherexamplesabove,these datademonstratethat population trend cannot reliably be ascertainedfrom numbersof dead bears.
325
TrendAscertainedfromAreaof Habitat
It seems almost tautologicalthat bear populationsdecline as a resultof habitatloss. However,the explanation
for this relationshipis not as simple as it may at first appear. If humansdid not exploit bears, bear populations
would likely exist at or nearthe carryingcapacity(K) of
the habitatover the long-term. Any loss of habitatin this
case would diminishK, eventuallyresultingin a population decline from increasednaturalmortality,diminished
reproduction,or both. In the moder world, however,
very few bearpopulationsexist at K. Conceivablythen,
habitatloss would not necessarily cause a populationto
decline. As an example: if, due to humanexploitation,a
bear populationexisted at 1/3 K, and the area of habitat
was reduced by 1/3, this reduced area could still easily
supportthe existing population, which - other things
being equal - would now be at 1/2 K (Fig. 1).
This seeming paradoxis resolved by consideringfurther ramificationsof the loss of habitat. If the level of
human exploitationremainedconstant,the above situation might indeed occur;habitatcould be lost withoutaffecting bear numbersuntil the point that the remaining
population,confined to a smaller area, exceeded K. In
reality though, bear mortalitywould likely increase inside the smaller patch of habitatbecause of heightened
human exploitation (Fig. 1). Exploitationlevels would
tendto increasefor severalreasons. (1) The reducedarea
would increasethe proportionof bearsliving at the edge,
andthese edge animalswouldbe morevulnerableto hunters and also more likely to wander into adjoining crop
fields and be killed as pests. This explanationseemed to
account for dramatic declines in orangutans (Pongo
pygmaeus) following logging (van Schaik et al. 2001).
(2) The diminishedsize of the patchwould makethe interior areamore accessible to huntersthat kill bears either
intentionallyor inadvertentlywhen seeking otherspecies
(e.g., by snaring);in essence,thereducedareawouldlessen
the chance for some part of the region to function as a
bear sanctuary. (3) Because bears are known to travel
widely,especiallyduringyearsof naturalfood failure,they
would be more likely to leave the bounds of the smaller
patch of habitatand thus be exposed to greaterhuman
contact. Recent studies have shown that althoughprotectedareas(e.g., nationalparks)arereasonablyeffective
in maintaininghabitat(vegetation)for animals(Bruneret
al. 2001), the persistenceof wide-ranginganimals(including bears),arestronglyrelatedto edge effects (Woodroffe
and Ginsberg 1998, Revilla et al. 2001) and surrounding
humandensity(Woodroffe2000). Among the carnivores,
it is ironicthatthemoreopportunistic-natured
bears,which
can often adaptto alteredhabitats,are thusmoreproneto
encounteringhumansand associatedrisks of mortality.
Therearealso many additionalsynergisticinteractions
326
Ursus 13:2002
A.
B.
-
Fig. 1. Hypothetical representation of the effects of habitat loss on bears. In panel A, 10 bears, whose home ranges are
indicated by convex polygons, are below carrying capacity because of human exploitation. In panel B, these same 10 bears
are forced into a smaller patch of habitat, the fringes of which have been converted to agriculture. This remaining patch of
habitat might still suffice to support the 10 bears. However, the smaller size and more irregular shape of the patch makes bears
more vulnerable to human exploitation because bears at the edge may be more prone to venture out into the agricultural fields,
and people can more easily reach once-secluded areas in the middle.
between habitatloss and other factors that might impact
bearpopulations.Smallpatchesof habitataremoreprone
to catastrophicfires or food failures(Cochrane2001) and
have less capacity to regeneratefruit-bearingplants because frugivorousseed-dispersersare less likely to visit
there (Cordeiro and Howe 2001). Shrinking, isolated
patchesof habitatalso may be less likely to attractimmigrantbears, so whereas local overharvestin contiguous
habitatcan be overcome throughsource-sink dynamics
(what Brown and Kodric-Brown[1977] called the "rescue effect"), small, insular patches of habitatare more
prone to extirpation(Peres 2001). Finally, and perhaps
most importantly,decreased habitatlimits the potential
for a populationto increase;even if habitatloss does not
directly cause a populationdecline, it may preclude recovery.
For these reasons, habitatloss should be foretellingof
reducedbearnumbersandpopulationviability. However,
the actual relationshipbetween habitatloss and population decline is far from clear. Moreover,sustainedor increasedhabitatis not necessarilyindicativeof a stableor
increasingbear population. These points are illustrated
by examples from Asia.
Giant Pandas in China.-Two range-wide surveys of
giant pandashave been conducted(and a thirdis nearly
completed). These surveys accomplished 2 things: (1)
they estimatedpandanumbers,and (2) they estimatedthe
areaof remaininghabitat. In the first survey,conducted
during the mid-1970s, some 3,000 people scoured the
panda's range, recordingpanda sightings and scats. A
"rough"populationestimateof 1,050-1,100 was obtained
(Schaller et al. 1985:15-16). This narrowrange belies
the inherentinaccuraciesof the method employed and
variabilityamongsurveyparticipants(Schaller 1993). A
decade later,a smallerteam of 35 biologists repeatedthe
surveyusing morerigoroussamplingproceduresto measure density of sign, including both scats and bedsites.
The resulting estimate of about 900-1,400 pandas provided no indicationof populationchange.
A majorfinding from these surveys, though, was that
pandahabitatwas being lost at a rapidrate. Largetracts
of agriculturalland bisected the range into small, fragmentedpopulations. Moreover,low elevation areasthat
once likely providedoptimalhabitatwere no longeravailable to pandas(Reid andGong 1999). In response,many
more protectedareashave been established(total>30) to
preventfurtherloss of habitat. However, it has become
increasinglyclear thatthis alone is insufficientto ensure
viability of panda populationsbecause these protected
areas are small and disconnectedby expanses of unsuitable habitat (Loucks et al. 2001); furthermore,habitat
quality,even within some of the protectedareas,is deteriorating.A case in point is WolongNatureReserve,one
of the originalandpresentlylargestof the NatureReserves
establishedexplicitlyfortheprotectionof pandas.Wolong
is also an InternationalBiosphereReserve and the site of
botha pandabreedingfacility andthe firstintensivestudy
of radiocollaredpandas(Schalleret al. 1985). In 1975,
the size of this reservewas expanded10-fold (to 200,000
ha) to improve protectionof pandahabitat. Since then,
the humanpopulationwithin the reserve (mainly minority ethnic groups, who are exempt from China's restric-
UNCERTAINTIES
INPOPULATION
TRENDS* Garshelis
tions on family size) has grown by nearly 70% and the
numberof households has more than doubled (Liu et al.
1999). Numberof householdsis significantbecause it is
related to timberand fuelwood consumption,which has
increased dramatically(An et al. 2001). Accordingly,
suitabilityof the habitatfor pandasin Wolonghas steadily
diminished(Liu et al. 2001a). Thereis some debateas to
whetherWolong is atypical (Baragona2001, Brooks et
al. 2001) orjust the worst-caseof a growingproblem(Liu
et al. 2001b), but either way it exemplifies the point that
habitatqualitycan deterioratefromthe bear'sperspective
while outwardlyseeming intactfromthe humanperspective.
A good deal of effort is presently being expended to
map as well as assess remainingpandahabitatusing sophisticatedproceduresfor estimatingdensityof theirstaple
food, bamboo, from satellite imagery (Lindermanet al.
2000, Loucks and Wang 2002). This is a promisingapproach,althoughthe knowledgeto define suitablehabitat
for this species is still lacking(e.g., species anddensityof
bamboo, overstorytrees, den trees, hill slope; Reid and
Hu 1991, Reid and Gong 1999). Thus, quantifying
changesin densityof bamboo,althoughbetterthansimple
habitatmapping,might still not accuratelydepictpopulation trend(Reid 1994).
Sun and SlothBears in SouthernAsia.-During 199496, J.L.D. Smith and I attemptedto initiate a field study
of sun bears in Thailand. Our greatestdifficulty was in
locating an area with sufficient bear density. The Khoa
Ang Rue Nai Wildlife Sanctuaryin southeasternThailand was recommendedto us because it had a new researchfacility andsatellitemapsshowedit to have a dense
forest. The southernborder of the reserve abuts other
densely-forestedprotectedareas. Stewart-Cox(1995:107)
characterizedthis areaas "thelargesttractof lowlandevergreenforest in Thailand." A few roads and trailspenetratedthe forest,which facilitatedaccess for trappingand
radiotracking.The mainentrancewas guardedandgated,
and therewere several guardstationsinside. Fromthese
indicationswe expected this to be an ideal study site.
We set out trapsand baits and conductedsign surveys.
Although we found some old sign, we soon concluded
thattherewere few bearsin this reserve;in fact, therewas
little sign of any medium-largemammals,even at places
where they would typically congregate,such as fig trees
(Ficus spp.) laden with fruit, salt licks, and waterholes.
We heard numerous reports of poaching, saw signs of
poachingencampments,andheardgunshots. One nighta
binturong (Arctictis binturong) was poached near our
camp. We noticedthatduringboth day and night,motorcyclists rode freely aroundthe closed gates and past the
guards. We learnedthatone of the roads throughthe reserve was a main thoroughfareconnecting two parallel
327
highways. This sanctuarywas certainlynot the "secluded
world"thatStewart-Cox(1995:107) had described.
Despite suitable habitat, this area exemplified what
Redford(1992:412)calledan "emptyforest.""Oftentrees
remainin a forest that humanactivities have emptied of
manyof its largeanimals...We mustnot let a forestfull of
trees fool us into believing all is well."
We encountered a similar situation with sloth bears
(Melursus ursinus) in Nepal. We surveyed their entire
range,a narrowstripof lowlandforestandscatteredgrasslands called the terai. Sloth bears were abundant in
Chitwan National Park, in the center of this range, but
were absentat the easternand westernextremitiesof the
range,despitesuitablehabitat. These areashad good forest cover and abundanttermites (a staple food for sloth
bears)(Garsheliset al. 1999a), but sloth bearshad apparently been poached out during the previous 2 decades
(Garsheliset al. 1999b), creatingvacantbearhabitat.
Sun Bears in Borneo.-Meijaard (2001) reportedjust
the opposite situationfor sun bearsin Kalimantan(IndonesianBorneo). Here, disappearingforests seemed to be
filled withbears,despitesupposedperiodsof heavypoaching. Duringthe 1970s poachingof sun bearsappearedto
be rampantin Indonesia,as evidenced by the amountof
bile illegally exported. During that decade, Meijaard
(1999) estimatedthatgall bladdersfrom about7,000 Indonesian sun bears were sent to South Korea;additional
shipmentsof gall went to other countries. I previously
showed thatquantitiesof tradedbile cannotbe converted
to reliable estimates of numbersof dead bears, or even
used to construetrendsin levels of bear mortality(Box
1). Nevertheless,it appearsfromthepresentlylow amount
of bile exported,low in-countrydemand,and according
to informationfromlocal people, few bearskilled for their
parts,thatduringthe past 2 decades,the tradein partshas
not resulted in large numbersof bears killed (Meijaard
1999).
Interviewswith local people across Kalimantanin the
mid-1990s indicatedthat sun bears were still "relatively
abundant"in most forested areas (Meijaard2001). The
forests, however,were rapidlybeing cut, which presumably would escalatehuman-relatedmortalityandthusreduce numbersof bears (Fig. 1). It is difficult, though,to
acceptMeijaard's(2001) estimatethathabitatloss caused
10,000 sun bears to die in Kalimantanduringthe 1980s,
given his evidence that human-causedsun bear deaths
appearedto be relatively low duringthat decade. Also,
while habitatloss is obviouslytroubling,equallytroubling
is Meijaard's(2001) tenuous predictionthat within anotherdecade, 14,000-28,000 more bears will die.
An irony in presentingsuch alarmingnumbersis that
one coulduse themto back-calculateanestimateof present
numbersof sun bears. Meijaard(2001) convertedhabitat
328
Ursus 13:2002
loss to numbersof dead bears using a "verycrude"density estimate of 1 bear/4 km2presentedby Davies and
Payne (1981). This estimateof densitywas derivedfrom
only 2 bearsightingsand9 observationsof sign. Extrapolating this density to all of Kalimantan would yield
>90,000 sun bears. Extendingthis densityto forestedareas of Malaysian Borneo (Sabah and Sarawak) and
Sumatrawould increasethe total to about 190,000 bears
(forest areasfrom Mayauxet al. 1998). Even if sun bear
densitiesin mainlandsoutheastAsia are much lower, the
total world populationwould still well exceed 200,000,
which would makethis species numericallyequivalentto
brownbearson a global scale, and second only to American black bears.
The reality is that sun bears are listed by the IUCN as
"datadeficient,"becausereliableestimatesof population
size and trendare unavailable(Baillie and Groombridge
1996). Creatingunsubstantiatedestimatesin the hope of
rousingmoreconservationinterestmay,as illustratedhere,
contravenethe intendedresult. Withoutfar betterinformationon the relationshipbetweenbeardensityandhabitat, attemptsto quantify bear numbersand trends from
forest cover dataare likely to be misguided.
IRONIESREGARDINGHUNTINGAND
TREND
POPULATION
A particularlynoteworthyirony regardingbear populationsis thatmost legally-protectedpopulationsseem to
be declining,whereasmosthuntedpopulationsareincreasing. One explanationis thatprotectedpopulationstendto
be small, and thus moreproneto decline as a simple consequenceof low numbers(Caughley 1994). Anotherexplanation is that many of these legally-protected
populationsare really heavily exploited. Oftentimes,the
level of humanexploitationmay be less undera system
of managedhuntingthan supposedtotal protection. The
reasons for this seeming contradictionhave a lot to do
withthe people,finances,energies,andideologiesentailed
in a managed harvest, resulting in an infrastructureof
managers,scientists,bureaucrats,and hunters,with nonhuntersandanti-huntersas overseers.This complexstructureis oftenlackingin the managementof protectedareas.
However,it is also truethatcountrieswith managedbear
huntingtend to have strongereconomies, which can supportbear managementactivities (e.g., research,enforcement) better than countries where hunting is banned.
These points are illustratedfirst by contrastingthe management of Americanand Asiatic black bears, followed
by an example regardingpolarbears (U. maritimus).
AmericanversusAsiatic Black Bears.-The 2 species
of black bears are similarin terms of their life histories,
and seem similar in terms of reproductivepotential, al-
though reproductivedata on wild Asiatic black bears is
presentlyinsufficient to enable a true quantitativecomparison (Garshelis 2002). However, the 2 species are
managedverydifferently.Legalhuntingis themainsource
of mortalityfor American black bears in most parts of
theirrange,whereashuntingfor Asiatic blackbearsis legal only in Japan.Most Americanblackbearpopulations
appearto be increasing(Williamson2002), whereasAsiatic black bearsarethoughtto be decliningin most areas.
The difference is that human exploitation is monitored
and controlledin the formercase, surreptitiousin the latter.
A reviewer of this paper asserted that the cause and
effect thesis posed here is reversed. That is, legalized
huntingdid not resultin numericallyabundantbearpopulations;rather,huntingwas legalized because bearswere
numericallyabundant. I disagree with this. American
blackbearswereseverelyover-exploitedthroughtheearlymid 1900s. Althoughregulatedexploitationof otherNorth
Americanspecies, such as white-taileddeer (Odocoileus
virginianus),datesto the 1600s (GilbertandDodds 1987),
black bears were much less valued as food so did not inspire efforts to limit the take. Moreover,bears did not
generate much interest among recreationalhunters on
whose behalf game laws were made (Schullery 1983). In
fact, mainly duringthe 1800s and early 1900s, federal,
state, and local governmentssupportedprogramsto destroybothblackbearsandgrizzlybearsbecausethey were
considereddetrimentalto raising livestock and crops as
well as potentially dangerousto people (Spencer 1955,
Cardoza1976, Brown 1996). An evolution in ideology,
beginningin some U.S. statesin the early 1900s, eventually led to the designationof black bears as a big game
species, with the objective of a sustainedharvest(Miller
1990). These laws were passedbecausebearpopulations
had noticeably diminished. Minnesota was one of the
last states to classify black bears as big game (1971). In
one Minnesotacounty where bears had been considered
"verynearlyextinct"priorto theirbig game listing (Cahn
1921:70,SpecialCommitteeon the Conservationof Wildlife Resources1940),a long-termtelemetrystudyrevealed
a high density of bearsfollowing 20 years of legal hunting (D. Garshelis,unpublisheddata).
There are many factors - economical, political, historical, cultural,and spiritual- that make it difficult to
transferto Asia the Westerntraditionsof sustained-yield
hunting. Proponents of sustainable use in developing
countriesarguethat people are more apt to conserve resourceswhen they have a vested interestin a returnfrom
theseresources(Gadgil1992,Kothariet al. 1995,Saberwal
1996). Others,though, have observed that high human
densities, abjectpoverty,class systems, and corruptgovernmentscreate a situationwhere it is nearly impossible
UNCERTAINTIES
INPOPULATION
TRENDS* Garshelis
to regulate harvests (Bennett and Robinson 2000,
Madhusudanand Karanth2000, Meijaard2001).
A high marketvalue for bearsin Asia makes the regulation of harvestan even more dauntingproblem. In Korea, for example, Asiatic black bears were subjectedto
the same sort of government-supportedremoval efforts
as Americanblackbearsduringthe early-mid1900s (Won
2001). Unlike the situationin North America, however,
Korean bear populations continued to plummet from
overexploitation into recent times because they were
soughtcommercially. A lesson learnedduringthe evolution of the NorthAmericansystem was thatmarkethunting was detrimental to wildlife populations and was
thereforeincompatiblewith recreationaland subsistence
hunting(Geist 1988, 1994). In fact, recreationalhunting
enthusiastswere largely responsible for legislation that
eventuallyprohibitedmarkethuntingfor wildlife in North
America (Reiger 1978).
Harvestinganimalsfor profit,though,is not uniformly
detrimentalto wildlife populations. In North America,
many species of furbearingmammalsaretrappedspecifically for sale of theirpelts, so the kill fluctuateswith fur
prices;nevertheless,theirpopulationshave been carefully
managed by governmentagencies (Novak et al. 1987).
In severalEuropeancountries,huntersroutinelysell their
game for personalprofitor for income for the landowner
or huntingclub; in some cases, hunterscan only retaina
portionof theirtake. This system has workedfor centuries (Bolen and Robinson 1995). In Japan,Moll (2001)
suggested thata prohibitionagainstthe sale of bearparts
might lead to diminishedinterestin legitimatebearhunting and higherprices for beargall, which togethercould
result in reduced stewardshipof the resourceand hence
increaseddangerof bearsbeing over-exploitedby poachers.
To be clear,my purposehere was to pointout the seemingly paradoxicaleffects of legal hunting,not to suggest
that sporthunting should be promotedwhere it does not
now occur. Simplyinstitutinga legal harvestis obviously
not the solution to declining bearnumbers. Historically
though, in both North America and Europe, managed
huntinghas been an effective system for protectingbear
populations.It has workedbecauseit has enlisteda clientele interestedin ensuringcontinuedabundanceof the resource. It also has worked because, for species such as
bears that can be a nuisance and a threat,it transfersthe
killing of animals from the general public to a smaller
groupof people (i.e., the hunters). Both these issues have
been instrumentalin shapingbear managementand conservation in North America, Europe (Klenzendorf and
Vaughan1999,Zedrosseret al. 2001), andJapan(Huygens
et al. 2001, Moll 2001). Linnell et al. (2001:348) commented "Thereis no doubt that the concept of hunting
329
large carnivoresas game species is far older in Europe
thanin NorthAmericaandhas contributedgreatlyto their
persistence."Ironically,in places suchas IndiaandNepal,
wherebearhuntingis now prohibited,preservesthatwere
set aside explicitly for hunting (by both local and European aristocrats)duringthe 1800s formed the basis of a
system of parksand wildlife sanctuariesthatnow constitute virtually the only remainingareas of intact habitat
withviablepopulationsof largemammals,includingbears
(Israel and Sinclair 1987, Mishra and Jefferies 1991,
Rangarajan2001; negative consequences of these royal
hunts and exclusionary policies notwithstanding
[Saberwalet al. 2001]).
Polar Bears.-During the 1960s it became evident that
polar bears were being over hunted. In 1973 an historic
conservationagreementwas signed among all 5 nations
with populationsof polar bears (U.S., Canada,Norway
[for Svalbard],Denmark[for Greenland],and the former
U.S.S.R.). Interestingly,the InternationalAgreementon
the Conservationof PolarBears (InternationalLegal Materials 13:13-18), which took effect in 1976, did not prohibit hunting,but ratherlimited it to native people using
traditionalmethods (IUCN/SSC Polar Bear Specialist
Group1999). Withinthis restriction,the membernations
went in differentdirections. Canadianjurisdictionsimposedhuntingquotasin mostareas,whereasthe U.S. could
not, underthe constraintof the MarineMammalProtection Act of 1972 (16 U.S. Code 1361-1407). However,
non-mandatoryharvestguidelines have been developed
for native communities in Alaska. In Greenland,there
are no quotas on polarbears but the harvestis limited to
native people who hunt or fish full time. In Svalbard,
huntingof polarbearswas forbiddenafterthe Agreement.
In Russia, a prohibitionon the huntingof polarbearspredated(1956) the Agreement.Russiathusappearsthe most
restrictivefor the longest time, yet in reality,the strongest
concerns about poaching polar bears exist in Russia
(IUCN/SSC Polar Bear Specialist Group 1999). What
may superficiallyseem ironicbutpertinentto this discussion is a recentagreementto permitnativeRussianpeople
to huntpolarbearsin the populationsharedwith Alaska.
The presumptionis thata legal hunt,with the self-serving
interestto remainwithinsustainablelimits,wouldbe more
effective at conservingthispopulationthanstriving(probably unsuccessfully) for total protection. Management
for harvesttends to be more successful because it broadens the numberand scope of people with a stakein maintaininga healthypopulation.
UNCERTAINTY
AND CONSERVATION
The only real certaintyin bearconservationis thathumanintrusion,via both directover-exploitationandhabi-
330
Ursus 13:2002
tatdestruction,is the mainfactorthreateningbearsworldwide. The degree of threat,however, is very uncertain.
The best informationexists for NorthAmericanand European bear populations. Geographic ranges are generally well-delineated, and population estimates and
growthrates, though often inexact, are usually based on
some research data (Table 1). For Andean bears
(Tremarctosornatus) of South America, there are good
distributionmaps but no data-basedestimates of abundance or trend (Peyton et al. 1998). Good range maps
and an estimateof populationsize exist for giantpandas,
butthereis no good informationon populationtrend(Reid
andGong 1999). Verygeneralizedrangemaps,poorpopulation estimates, and weak evidence of populationtrend
are available for the other Asian species (Table 1). All
these species, though,are perceivedto be in trouble.
To aid in the conservationof these species, many believe it is necessary to provide populationnumbersand
extinction scenarios. Populationviability analyses are
certainlyproductiveexercises thatmay be especially importantin illuminatingsensitivepopulationparametersand
weaknessesin the data(Sether et al. 1998, Wiegandet al.
1998);however,these shouldnot be confusedwith actual
populationprojections(Mills et al. 1996, White 2000).
We have rarelybeen able to trackpopulationtrendsin the
present,andbecausewe lack vital biological information
for many of the species (Garshelis 2002), it seems improbablethatforecastingthe futurewould be very accurate. Referringto largewhales, but describinga situation
applicable to bears, Gerberet al. (2000:318) observed:
"ourlimitedknowledge... makes it extremelydifficultto
quantifythe degree to which a populationmay go extinct
in a specific period of time... Unfortunately,the public
and the press have not been entirelyawareof these difficulties. Worse,advocacygroupson both sides of the environmentalcontinuum and even some scientists have
filled this void with inaccuracies."
Some believe that admitting to uncertainty would
muddythe message, and therebydetractfrom conservation initiatives. Thatview holds thatfirm,bold, andclear
assertions,even if not entirelybackedby factualinformation, yield betterresults in terms of protectingenvironmentalwelfare thandoes revealinguncertainties.Those
opposing this approachwarn of blurringthe distinction
between science and advocacy, which can be especially
temptingwhen both are harboredin the same individual
andMcCoy
(Bowen and Karl 1999). Schrader-Frechette
(1999) arguethat occasionally compromisingscience in
favor of advocacy will ultimately create the perception
thatscience was abandoned.If we do not universallyadhere to all the principlesof science, then we must be prepared to wade into ethical battles, where scientific
viewpoints no longer have ascendancy.
There is an obvious counter-argumentto this reasoning: brandishinguncertaintymaynotbe a powerfulmeans
of swaying policies towardbetterconservationof bears.
Acknowledgmentof uncertaintyin the scientific arenais
one thing; highlighting it in the political arena is quite
another. There is certainly some wisdom in this, but I
offer severalreasonswhy thereis usually greatermeritin
makingthe uncertaintiesclearto the publicandthe politicians. (1) If new data do not supportprevious suppositions (e.g., about a population decline), and if the
uncertaintiesinherentin the original suppositionswere
not madeclear,scientific credibilitywill be damagedand
future conservationefforts based on scientific information may be compromised. (2) Optimismgenerallyprovides more motivation for conservation action than
pessimism(Beever2000), and,in manycases, uncertainty
provides a greaterarrayof optimistic scenarios. Uncertainty in this context should not be confused with ignorance,which is always detrimental(Garshelis1997). (3)
Incognizanceof uncertaintiesmay detractfromeffortsto
gathermoredataandimprovemethodologies. False con-
Table1. Relativedegreeof certaintyregardinggeographicrange,populationnumbers,andpopulationtrendsof the 8 species
of bears. Symbols (++ reasonablygood, + fair, 0 poor or nonexistent)representsubjectiveratingsby the author for
comparisonswithinand amongcolumns.
Informationalquality"
Species
Americanblack
Brown
Polar
Andean
Giantpanda
Asiaticblack
Sloth
Sun
a Based
Geographicarea
NorthAmerica
NorthAmerica
Europe
Asia
Arctic
SouthAmerica
Asia
Asia
Asia
Asia
Range
++
++
++
+
++
++
++
+
+
+
Numbers
+
+
+
0
+
0
+
0
0
0
Trend
+
+
+
0
+
0
0
0
0
0
mainly on Servheen(990), Servheenet al. (1999), Williamson(1999), Sathyakumar(2001), and Zedrosseret al. (2001), plus
accumulatedknowledge and personalexperience.
UNCERTAINTIES
INPOPULATION
TRENDS* Garshelis
fidence in presumptionsabout populationdeclines thus
may inhibitdiscoveries thatcould aid in detectingpopulation change. This is an extension of Gibbs et al.'s
(1998:940) view: "The primaryconsequence of failing
to improve methodologies for identifying population
changein ecology will be a chronicfailureto detectpopulation change. Unfortunately,these statisticalerrorswill
frequentlybe misconstruedas reflectingpopulation'stability,' lack of treatmenteffect, or ineffectivenessof management." Hence, if the uncertaintiesare not eventually
remedied,even effectiveconservationprogramsmay yield
no measureof success because it will not be possible to
detect a populationincrease.
I contend thatin the interestsof both science and conservation,biologists should emphasizethe uncertainties
of populationassessmentsandthusthe necessity for more
rigorous research. This may seem counter-intuitivein
terms of conservation,but the logic is this: in the presence of uncertaintyefforts shouldbe directedtowardensuringno irreparableharm. The wide rangeof uncertainty
aboutbearpopulationsshouldbe reasonenoughfor claiming a wide berthin erringon the side of caution.
ACKNOWLEDGMENTS
I thank S.D. Miller for the invitation and encouragement to write this paper. Commentsby an anonymous
reviewerandAssociate EditorL.S. Mills promptedme to
better elaborate my arguments. Discussions with C.
Servheenand S.C. Amstrupclarifiedissues regardingthe
tradein bearpartsand the huntingof polarbears,respectively. I am especially gratefulto J.L.D. Smithfor sparking my interest in Asian bears. This paper was written
with support of the Minnesota Departmentof Natural
Resources. Field workin Asia was supported,financially
and (or) logistically by the Thai Royal ForestryDepartment, the King MahendraTrustfor NatureConservation
(Nepal), Wildlife ConservationSociety, Centerfor Field
Research (Earthwatch), and the American Zoo and
AquariumAssociation ConservationEndowmentFund.
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