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A green arborealfrog.
Many species of frogs are threatened by pollution and the depletion of the ozone layer.
Mexico'sEnd-of-CenturyChallenge
Preserving Biolo grcetDiVersitY
Gerardo Ceballos*
( ( A
A
I
I
apMexicannamedFigueroa...
memoryperpetuatedin chroniclesof old
peared one morning bringing
books and on museum shelves.No
longercan anyoneenjoythe spectacleof
ut three superbwoodpeckers,
magnificentexamplesof the Carvpephilw
imperialis,extraordinarilylargeones.This
these birds among the pines on lands
broken by deep ravines and jagged
mouniains.One by one theyitorrmles-a
n.-. they were known by locally- disappeared,exterminatedby intense logging and hunting. It is likely that the last
splendid bird stands two feet high; its
imperial woodpeckerspent months,perhapsyearsin an intense,fruitless search
plumageis blackand white, and the male
for other specimensof his or her kind
sportsa red crest on its head that stands
until one clearmorning,like rnanyothers
in thosemountains,it too'tiits lastbreath.
out particularlyagainstthe snow."l
Exceptfor a smallgrouPbf scientists,the
world took no notice of its extinction.
That is how Norwegian anthropologist Carl Lumholtzdescribedthe imperial woodpeckerat the beginning of the
century. Considered the largest wood-
Unfortunately,this was not an isolated
case, and it is representativeof one of
peckerin the world, this bird lived exclu-
the most severeenvironrnentalproblems
sively in the foothills of Mexicos Sierra
Madre Occidental, from Sonorato Mi'
in the history of humanig: the loss of
biologicaldiversity.
In the last four centuries,more than
andhundredsof
400 speciesof vertebrates
choacdn.Unfortunately,it is now only a
* Researcher
at the uruauEcologyInstitute.
92
Habitat destruction is causing the extinction
of species like the black-tailed prairie dog.
invertebratesand plants have become
ii
Ecology
i
extinct. These:figures speak for them-
This populationexplosion,practically
habited.This changeddrasticallyin the
when comparedwith
but Xhqy:pale
se'lrres,
today'srate of extinction. Despite there
unknown until this century is a recent
followingdecades.By 1940,there were
phenomenon.Scientificand technological
already19.7million Mexicans;by,1990;
being no precisefigures becauseof the
suchasthe discoveryofvaccines
advances
8l million; andfive yearslater,95 million;
problem'scomplexity,thousandsof species
drop
andantibioticscauseda considerable
This makesan increaseof over 1000per-
becomeextinct everyyeal someapproxi-
in the deathrateand the populationbegan
cent sincethe beginningof the century.
the.figureat 50,000.,-{t the
mations:,put
to grow rapidly.At the beginningof this
sametime, thousands,pefus rml'lionsof
specieslare endangered.The overwhelm-
century the Earth had about I billion
Estimatesindicatethat this figure will
doublein the next 25 years,and it is to
inhabitants;30 yean later,that figurehad
be expectedthat the negative'impact
ing, seeminglyendlesslist containsseveral
speciesof everygroupqf.'planti and ani
doubled.By 1970,there were about 3.5
on the environmentwill parallel that
billion human beings on the planet, a
growth.
rnals,and it getslongereveryday.
numter that increasedby approximately
The extinction of specieshas pro-
The causesof extinctionvary wrdely,
there are 5.9 bil70 million yearly.Today,
found biological,cultural and economic
but they all boil down to a singlefactor:
lion of us, and the yearlyincrementis 85
implications.The history of the evolu-
the sheermagnitudeof humanactivity.Its
million. As incredible as it seems,the
tion of humanityand the developmentof
environmentalimpact in recentcenturies
humanpopulationhasgrownas much in
rites, art and customshave been inti-
has been severe.Global pr,oblemslike
the last25 yearsasit did in the time since
matelylinked to nature'sdiversity.There-
atmosphericwarming,the thinningof the
ozonelayeqpollution,the destructionof 'fo-
the first human being appearedmillions
fore, the impoverishmentof biological
of yearsago.
resourceslimits the possibilitiesfor cul-
restsandjungl.t, the desertificationof enor-
Mexico is no exception.lts popula-
mouse{pansesof the planetssurface,and
tion hasalsogrownrapidlyin this century.
I.{evertheless,
the importanceof preserv-
the loss of biologicaldiversityare caused
In 1910,w-henthe countrycelebratedthe
ingbiologicaldiversitycan only be appre-
exclusivelyby the population explosion,
the most significantevent of the Earth's
first centennial of independenceand
ciated,inits true magnitudeif we look at
the total populationwasnearly8 million,
its role in natural systemsand the ser-
last 65 rnillion vears.
enorTnousstretchesof land were unin-
vices it offers to humanity.Biological
tural enrichment and diversification.
Toucans are arnong the many species of birds affected by illegal pet trade.
93
Vorcfsclr Mtxtco ' 48
wild.
The Mexican wolf (Canr.stupus baiteyi)and the Califomia condor (Gymnogyps cafifomianuslUecameextinct in the
diversityis the basisfor the structureand
functioning of nature. Each speciesis
from the Sun'sultravioletrays;the stabi-
the Mexicanwolf, the seaotter,the Guadalupe caracara,the California condor,
like a cog in an extremelycomplexseries
lization of the climate; and the moderation of extreme temPeratures,wind and
of interactionsamong them and their
waves.Clearly,the reasonsfor preserving
physical and biological environment.
biologicaldiversityarenot onlyphilosoph-
of species,
&sappearance
The progressive
ical,moral,religiousandethical,but above
knows how many plant or invertebrate
specieshavebeenlostwithout evenbeing
that is, of the cogs,first weakensand then
all, pragmatic.
registeredby science.
impedesthe correct functioning of biologicalsystems.
Under normal conditions, human
Mexico, a country of legendarycultures,describedin the nineteenthcentuV by German scientist Alexander von
is sufHumboldtasa biologicalparadise,
beingsgatheran enorrnousvarietyof benefits --called nature'sservices- from
fering todayfrom one of the world'smost
The long list of envinaturalecosystems.
severeextinctionproblems.The situation
ronmentalservicesincludesthe mainte-
of Mexican flora and fauna is extremely
precarious:around25 percentof all the
nance of the proportionsof gasesin the
cyclethat providesfreshwater;provision
vertebrates,almost 750 species,are in
dangerof extinction.Many of them, like
of productsfor agriculture,food,raw ma-
the 300 remainingscarletmacawsscat-
terials,medicineand industrialprocesses; the purificationof the air and water;
tered throughoutthe LacandonJungle,
or the perhaps500 vaquinporpoisesstill
the mitigationof floodsand droughts;the
swimming in the dun-coloredwaters of
atmosphere;control of the hydrological
the passengerpigeon and the Salado
shiner (Tablel). What is worse,nb one
The anthropogeniccauses of the
extinctionof speciescan be classifiedas
direct and indirect activities.The former
are those that, like trafficking in animal
species,illegal hunting and eradication
programs,that expresslyseekto obtain a
species with desirable characteristics
"undelike its fur or flesh,or to eliminate
sirable"specieslike pestsor predators.
This kind of activity has caused the
extinction of specieslike the Mexican
wolf (Canis lu.yusbaileyl and the Mexican grizzly(Unm arctns).
detoxificationand decompositionof waste;
the upperGulf of Califomia,are at immi-
Indirect'activitiesinclude pollution,
deforestationand fragmentationof nat-
reqovatiol ofthe soil,
the generationrand
,nentriskof extinctionif intensiveprograms
ural environments.These activities do
aswellas the maintenance',#itsfertility;
to preservethem are not established.
not have as their exPressobject any Particular species,but they do affect flora
the pollination of crops and natutaluqg:
Like'the imperialwoodpecker,at least
etation; the control of major,pests that
44 other vertebratespecieshavebecome
endangercrops;,the dispersalof seeds;
extinct in Mexico during this century
and fauna simultaneouslyand are the
of many
main causeof the disappearance
the translocationof nutrients; protection
among them the Mexican grizzlybear,
speciesworld-andnationwide.Forexam-
94
Ecology
Wood storks are threatened in Mexico.
Many speciesof reptilesendemicto Mexico,like the skink, are sold illegalyin the U.S. and Europe.
ple, the deteriorationof the environment
sity should be the priority in Mexico's
senationof biologicaldiversity.
A plan of
precipitatedbv the destructionof enor-
natural resourcemanagement.Conser-
this kind would makeit possibleto know
mous stretchesof naturalhabitatswith
ration and development
shouldnot clash
in detailthecountry'sbioticresources
and
the rapidadvanceof the agricultural,for-
sincethere can be no long-termharmo-
determine developmentstrategiescom-
est, cattle raising and urban frontiers,
nious developmentif natural resources
patible rryiththe conservationof thesere-
seriouslyendangersthe perpetuationof
deteriorate.The conservationof Mex-
,sources,particularlywith the long-term
entire ecosl,stemsand thousandsof
ico's biologicalriches is important for
philosophical,ethical, moral, biological,
maintenanceof endangeredspecies.This
plantandanimalspecies.
It is estimated,
fbr example,that approximately
700,000
would be only the first stepin consolida-
hectaresof land are deforestedevery
cultural,economicandsocialreasons.
This
rryealth
represents
an enorrnoussourceof
stratingthat despitea complexenviron-
year in Mexico, putting it among the
economicresourcesvr,'hich
can be trans-
mental situation,the necessaryvision
countriesof the u,orld with the highest
formedinto noticeableimprovementsin
existsto adoptmeasuresaimedat correct-
ratesof deforestation.
the quality of life and well being of all
ing the problems.The federalgovemment's
N{ore than three decadesago, cele-
ting conservation
effortsand in demon-
N'texicans.However, conservationof
development model requires profound
Nlexico'snaturalresourcesis only berng
revisionsto minimizedamageto the envi-
caried out thanksto the effortsof a small
group of people and institutionsand is
ronment and harmonizeit with rational
ing an enormousand difficult problemin
the conservation
of its resources.
No pal-
insufficient.For example,only between
of natural resources.
This is probablyone
bratednaturalistA. S. Leopoldsummed
"Mexico
up the situation,saying,
is fac-
management
andlong-termconservation
liative measurewill solve it. \Vhat is
3 percentand 4 percentof Mexico'ster-
of the most outstandingchallengesthat
requiredis a nationwideeffort...The con-
ritory is includedin the National System
both societyand govemmentmust meet
servationof u'ild faunais impossiblewith-
of ProtectedAreas.Despitesomeadvancesin the lastsixyears,the situationin
in the twenty-firstcentury. NM
out payingattention to other resources
-*oil, forestsandwater...The future...will
protectedareasis critical: most reserves
be determinedin the final analysis,by
have severeproblemsof land tenure,
the country'sresponseto the challengeof
humansettlemenrs,illegallogging,fires,
conservation."2
hunting and lack of infrastructure.
Leopolds appreciationwas conect.
Govemmentand societymustjoin for-
Actuall.v,
conservation
of biologcaldiver-
cesto createa nationalplan for the con-
NorEs
rCarl Lumhohz. El Mexico derconocida
09A2;
reprint, Mexico Cityr Insriruto Nacional Indigenista,1979).
2A.S. leopold, "Faunasilvestrede M6xico,"rMEnNAfi
(MexicoCity)(1965).
95