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The llanos

Authors:
Onnoco
goose
(Neoc
h
en
jubata)
in the Venezuelan Llanos.
L
uiz
Clau
dio
Marigo
266
1995).
The
dominant
vegetation is a gallery forest with
several
dominant
tree species like pal
ms
(Copemicia
tec-
torum), saman (Pithecellobium saman), masaguaros
(P.
guachapele), figs (Ficus spp.), caruta (Genipa americana),
palo de agua (Cordia collococa),
and
camoruco (Sterculia
apetala) (Ramia 1967; Troth 1979). Occasionally,
there
may
also
be
larger
trees
such
as
T
erm
inalia amazonica
and
Ceiba pentandra
that
can
reach
over
50 rn (
Hernan-
dez
et
al. 1994),
and
even
the migh
ty
caoba
or
mahogany
(Swietenia macrophylla) is
somet
im
es
pr
esent
(Cesar Bar-
bosa, pers. comm., 2002).
The
next
formation is
the
bajios,
which
are
lower
regions
found
further
away from
the
rivers
and
where
sedimentation
of
finer particles takes place.
They
cov-
er
al
most
half
of
the
total surface
of
the
overflow plains.
They
have
po
or
er
drainage, th
eir
acidic soils
contain
a
high
proport
i
on
of
expandable clay,
and
they
are
riche
r
in
organ
ic
matter
than
the
bancos (Lopez
Hernandez
,
op.
ci
t.
). During the rainy season,
the
bajfo is partially cov-
ered
by
water,
but
it
dries
out
completely
in November
or
December. Very few
trees
can
grow
under
these con-
ditions,
among
them
the
palm
Copemicia tectorum
and
the
caujaro (Cordia sp.). Palm forests
of
Mauritia flexu-
osa, locally
known
as
morichales,
are
a]so
charac
teristic
of
the bajios,
and
reach
over
18
min
hei
ght
along water-
ways, in the
most
flood-sus
cep
tible areas.
This
is a high-
ly-productive association
that
provides food for
humans
and
vvi
ldli
fe,
as
well
as
thatching
material
and
fiber for
kn
itti
ng
hammocks
and
mak
ing cloth. Scattered through-
out
this formation is
an
interesting
lands
cape feature
locally
known
as
surales
or
topiales, consi
st
ing
of
thou-
sands
of
low
mounds
of
dirt
covered
with
grass (pre-
dominantly
Trachypogon spp.). In
the
rest
of
the
area, it
is
common
to find spiny shrubs, including barinas (Cas-
sia aculeata), guaica (Randia armatta), Mimosa pigra, M .
dormiens,
and
Hydrolea spinosa, and grasses
such
as Pas-
palum
spp., Paratheria prostata, Eleocharis spp., Leersia
hexan.dra,
and
Hym
enachne amplexicaulis (Ra
mia
196
7;
Troth 1979).
Esteros
are
the
third
and
1owest region
of
the
over
-
flow pl
ains
.
They
are ch
aracter
i
zed
by
poorly-
drained
soils with
very
fine texture in which
the
mai
n
route
of
water
loss is evaporation. As
the
dry
season progresses,
esteros
hold
water
l
onger
than
any
other
areas,
and
dr
y
up
on
ly
at
the
end
of
the
dry
season
(March
or
April).
Continued
flooding
throughout
most
of
the
yea
r
and
clay-heavy so
il
inhibit
most
tree
growth, with t
he
excep-
tion
of
occasional palms. Instead,
the
esteros
are
domi-
nated
by floating vegetation
of
wh
ich
Eichhomia cras-
sipes
and
E. azurea
are
particularly
prominent.
Other
co
mmon
floating e
lem
e
nts
are
Salvinia spp., Pistia stra-
tiotes,
and
Ludwigia spp., while the rooted vegetati
on
is
compose
d
of
Thalia geniculata, Ipomoea crassicaulis, I.
fi.stulosa, Eleocharis spp.,
and
Cyperus spp. (Ramia,
op.
cit.; Thoth,
op.
cit.).
Aeolli
an
Plains
are
located to
the
south
of
th
e over-
flow plains
an
d are
lar
ge extensions
of
dunes
indicative
of
arid conditions
during
glacial periods.
This
subregion
is
covered
mostly
by
low-productivity grasses (e.g. Pas-
palum, Trachypogon) (Sa
rmiento
,
op.
cit.).
The
gallery
forests al
ong
small st
reams
have
the
only
trees
in
the
area, with floristic compositi
on
being
sim
il
ar
to
that
in
the overflow plains.
Mo
richales also
occur
along rivers,
streams
or
pool
s,
providing
water
and
food for
many
animals,
and
often
have
the
hi
ghest
conce
ntrations
of
species
in
this subregion.
The
High
Plains
are
found
in
two distinct areas,
one
in
the
extreme
south
of
the Llanos
and
the
ot
her
to
the
east
of
the overflow plains.
The
re
li
ef
is slightly
more
hilly
and
it
is possible
to
find
eroded
mesas
composed
oflateritic
crusts
that
preven
t root
penetration
and
con-
strain tree growth. Soils are light
and
even
coarse, acidic
and
rich
in iron and
aluminum,
with the
predom
inant
vegetation
cover
bei
ng
grasses of1ow
nutr
itional value
(e.g., Trachypogon spp.) (Sarmiento,
op.
cit.). As
the
great
grasslands
of
the
open
savanna
come
closer to the
waterways, woodland
savannas
of
saladillo (Caraipa
llanorum) start to appear.
These
moderately high, region-
ally
endemic
woodlands
become
seasonally flooded and
their
most
prominent
characteristic is
their
ability to
inhibit
the
devel
opment
of
a
shrubby
understory, allow-
i
ng
a
herbaceous
one
instead.
There
are
other
inter-
es
ting
p
lant
associations
here
,
such
as
th
ose
formed
by
chaparro manteco (Byrson.ima crassifolia), a
th
i
ck
bark
tree
from
which
ta
nnins
are
obtained for the
leather
industry. Its fruit is also interesting,
as
it is highly fatty,
hen
ce
the
name
manteco ("lard"),
an
irresistible
tr
eat
for
many
animals, partic.ularly
the
white
-tailed
deer
(Odocoileus virginianus).
Other
forest associations in-
clude chaparro forest do
minated
by Curatella americana,
a species highly resistant to fire with large, coarse leaves
that
are
used as
sandpaper
by
local woodworkers.
Surales
or
topiales
may
also
be
found
scattered
through-
out this formati
on
, especially
in
areas
susceptible to
flooding
betwe
en
riparian
and
chaparro
fo
rests.
Pi
edmont
savannas
are
the
hi
ghest
part
of
the
Llanos
an
d are located
near
the Andes. Soils are
deeper
a
nd
rich-
er
due
to alluvial deposition from the Andes,
and
these
are
the
most
forested areas
in
the
Llanos.
Dr
y tropical
forest is
common
here
and
has
a si
milar
floristic
com
-
position to
that
of
the bancos.
Due
to higher
fe
rtility
and
the
larger areas
of
forest, agriculture
and
logging
have
taken a
stronger
toll
on
this subregion,
and
cattle ranch-
ing is slightly
more
intensi
ve
than
elsewhere.
The
average
temperature
in
the
l
ower
Llanos is
26
.
6°C,
the
mean
diurna
l fluctuation is 9.5°C,
and
the
mean
seasonal flu ct
uation
is 3.0°C. Precipitation varies
from 1 000
mm
on
the
easte
rn
si
de
to as
mu
ch
as 2 000
mm
in
the
Guaviare River, with
over
90%
of
th
e rain
falling b
etwee
n April
and
November.
The
period
between
January
and
April is
the
dry
season
when
all
the
water
bodies
shrink
or
disappear
entirely, with
the
on
ly
permanent
water
be
ing
in
the esteros
and
lagoons.
The
smaller
riv
ers
eventually
stop flowing,
making
it
necessary
for
aq
u
at
ic wildlife to rely
on
th
e d
eeper
por-
tions
of
these
waterways
to
survive. From
Jul
y to Octo-
ber,
there
is a distinct
wet
season
wh
en
the
savanna
floods
and
there
is
abundant
standing
water
du
e to rain-
fall
and
ove
rflowing
of
the rivers.
The
two
months
between
eac
h
seas
on
are
considered
transitional.
This
extreme
seasonality
is less
marked
towards
the
south
of
the
Colombian
Llanos,
where
t
he
dry
season
may
be
as
short
as
two
mo
nths.
Biod
iv
ersit
y
Plant diversity is fairly high, with 3 424
species
of
vascu-
lar
plants
recor
ded, while
endem
i
sm,
at
40 species, is
low (G.
Aymard
and
R.
Duno,
in
litt., 2002).
Among
the
endemics
are
species
like
Vernonia aristeguietae, Bour-
reria aristeguietana, Stilpnopappus pittieri,
S.
apurensis,
Hymenocallis venezuelensis, Eriocaulon rubescens,
Lim-
nosipanea temifolia,
and
Gustavia acuta
(Huber
and
Al
ar
-
con
1988).
It
is
i
mportant
to
highlight
the
unique
plant
communities
that
grow
on
the
many
rocky
ou
tcro
ps
found
throughout
t
he
high
plains.
These
have
a highly
distinct
ive f1oristic
composition
which
includes
Vellozia
lithophila, Navia
spp.
-a
small
bromellad
wit
h
sharp,
spiny
rosettes
on
the
tips-,
and
a
smal
l
pa
lm
of
the
genus
Syagrus
that
is
highly
resistant
to fire
and
which
sheds
its
leaves
as
a
surviva
l
strategy
during
prolonged
dro
ughts.
Many Llanos pl
ants
have
special
adaptations
to fire,
among
them
Curatella americana, Byrsonima crassifolia,
and
Bowdichia virgiloides,
which
have
very
thick
bark
insulating
the
tree.
This
feature
reaches
its
extreme
in
the
chaparote (Palicourea ri.gidifolia),
which
has
a
woody
stem
almost
2
cm
thick,
surrounded
by
another
2
cm
of
prote
ctive bark.
The
fauna
in
the
Llanos
is
both
abundant
and
diverse.
Birds
are
represented
by
approximately
475 species,
including
both
reside
nts
and
migrants
that
gather
in
large
numbers
during
the
dry
season
to feed
in
the
dry-
ing
wetlands.
Important
groups
include
herons
and
egrets, ibises, storks, ducks, shorebirds,
and
many
birds
of
prey
(Ph
elps
and
De
Schau
ensee
1978;
WWF,
in prep.).
Endem
i
sm,
however, is low, with
on
ly
the
Or
inoco soft-
tail (Thripophaga
cheniei)
considered
endemic,
al-
though
the
Orinoco
piculet
(Picumnus
pumilus)
can
be
considered
a
near
endemic.
Mamma
ls
are
represented
by
198
species,
including
59
spec
i
es
ofbats
(Ojasti
and
Baher
1986,
cited
in
Ojasti
1990;
CI
unpub
l
ished
data),
but
only
three
of
these
are
endemic.
Among
nonvolant
mammals,
the
most
abun-
dant
is
the
capybara
(Hydrochaeris hydrochaeris), a
rodent
adapted
to a
semiaquat
ic life-style. Following
in
abundance
are
white-tailed
deer,
which
are
commonly
seen
mingling
with
cattle,
and
this
is
one
of
the
main
causes
of
high
mortality
due to
hoof-and-mouth
disease
(Eisenberg
and
Po
l
isar
1999).
Other
mammals
found
in
the
savanna
include
edentates
like
the
giant
anteater
(Myrmecophaga tridactyla),
the
southern
tamandua
(Thmandua tetradactyla),
and
the
Llan
os
long-nosed
arrnadi1lo (Dasypus sabanicola);
and
several
carn
i
vores
such
as
the
crab-eating fox (Cerdocyon thous),
bush
dog
(Speothos venaticus), ocelot (Leopardus pardalis),
puma
(Puma concolor),
jaguar
(Panthera onca),
and
giant
otter
(Pteronura brasi.liensis).
Onl
y two
species
of
monkeys
,
the
red
howler
(Alouatta seniculus)
and
the
weeper
capuchin
(Cebus olivaceus),
occur
in
the
Venezuelan
Llanos,
whereas
as
many
as
six
occur
in
the
Colombian
p
ortio
n
of
this
region.
The
Colombian
spe
c
ies
include
again
the
red
howler
,
the
'"'
hite
-fronted
capuchin
(Cebus
albifrons)
replacing
the
weeper
capuchin
,
the
widow
monkey
(Callicebus torquatus),
the
squirr
el
monkey
(Sai-
miri sciureus),
and
two
species
of
night
monkey
(Aotus
bntmba
cki, A. trivirgatus), usually found in
gallery
forests.
The
only
endemics
are
the
Llanos
long
-
nosed
armadillo,
Orinoco
sword-
nosed
bat
(Lonchorhina ori-
nocensis),
and
O'
Connell's
spiny
rat
(Proechi.mys ocon-
nelli)
(WWF,
in
prep.).
Repti
les
are
very
abundant
in
the
Llanos,
with
a total
of
around
107
species
(
WWF,
in prep.).
Several
of
these
are
present
in l
arge
numbers,
in.eluding
the
giant
green
anaconda
(Eunectes mw"inus),
the
spectacled
caiman
(Caiman
crocodilus),
the
savanna
side
-
necked
turtle
(Podocnemis
vogli.),
the
green
iguana
(Iguana iguana),
and
the
tegu lizard (Titpinambis teguixin),
and
reptile
bi
omass
is
qui
te high.
Other
reptiles found in l
ower
num-
bers include
the
mata-mata
turtle
(Chelus fimbriatus),
the
scorpion
mud
turtle
(
Kinostemon
scorpioides),
the
yellow
-
spotted
Amazon
river
turtle
(Podoc
nemi
s unifilis),
the
giant Amazon river turtle
or
arrau (P expansa),
and
the
dwarf
caiman
(Paleosuchus palpebrosus).
Endemism
is
also
low
among
reptiles
with
one
endemic
species, a
dwarf
species
of
rattlesnake, Crotalus pifanonim,
and
two
near
endemic
species
,
the
savanna
side-necked
turtle
and
the
Orinoco
crocodile (Crocodylus intermedius).
Amphibians
are
very
abundant
,
and
especially
ubiq-
ui
tous
in
the
wet
season,
and
are
represented
by
around
48
species
with
six
endemics:
Kennedy
's
snouted
tree
frog (Sein.ax kennedyi), Blair's
snouted
tree frog
(S.
blairi),
Villavicencio
snouted
tree
frog (S. wandae), Mathias-
son's
tree frog (Hy/a m.alhiassoni), Eleutherodactylus mede-
mi,
and
Colostethus juanii (WWF', in
prep.).
The
most
common
species
i
nclude
the
cane
toad (Bufo marinus),
the
emerald-eyed
tree
frog (Hyla crepitans),
t11e
yellow
tree
frog (H. microce
phal
c
1)
, Rivera's
tiny
tree
frog (H.
minuscula),
the
Caracas
snouted
tree
frog (Scinax
ros-
trala),
the
Colombian four-eyed frog (Pleurodema brachy-
ops),
and
the
swimming
frog (Pseudis paradoxa).
Fi
sh
diversity is also
high
,
with
300
species
of
fishes
in
the
Llanos.
The
level
of
endemism
in
the
Ll
anos
is
not
well
known,
but
it
is
estimated
that
there
are
between
30
and
40
endemic
spe
c
ies
-although
some
of
these
might
occasionally
be
found
to
the
south
of
the
Orinoco
(
C.
Lasso, pers.
comm.,
2002).
Noteworthy
fish
include
several
species
of
catfish
(Brachyplatystoma fil-
amentosum,
Ps
eudopimelodus apurensis, Phractocephalus
hemilioptents), electric eel (Electrophorus elech'icus), fresh-
water
rays (Paratryg
on
air
eba, Potamotrygon orbignyi),
and
piranha
(Serrasalmus altuvei,
S.
elong
atu
s,
Py
gocen-
h1AS
notatus).
When
the
rivers
flood
the
savanna
,
the
fish
in
vade
the
newly-inundated
areas
to
forage
and
breed
,
and
then
return
to
the
livers
in
the
dry
se
ason
.
Howev-
Stnated heron
(Butorides striat
us
) eatmg a frog
t Tuny
Crocetta
I BI
OS
267
Above, the Orinoco crocodile
(Crocod
ylus
int
erme
dius
)
is
perhaps
the
most
important
flagship species
of
the Ll
anos
and
one
of
the world's most endangered
crocodilians. ft
is
also one
of
t
he
largest,
reac11ing
5-6 m in length.
"'
Michael
P.
Turco
On the opposite pa
ge,
red-
and
-gre
en
macaws
(Ara
chloro
ptera).
c
Patricio
Robles
Gil
/Sierra Madre
268
er, large
numbers
often fail to find
the
ir
way
ba
ck,
becoming
isolated
in
temporary
ponds
where
t
heir
den-
sity
increases
as
the
dry
season
progresses (Machado
Allison 1993).
Flagship
Species
The
Llanos is
noteworthy
for
having
several
flag-
ship
species
that
are
among
the
largest
in
their
taxo-
nomic
groups. Reaching
between
5
and
6 m
in
lengt
h
and
with
unconfirmed
sightings
of
animals
measuring
7 m,
the
Critically
Endangered
Orinoco crocodile is
one
of
the
larger crocodile species.
It
is also
one
of
the
most
threatened
species
of
crocodiles
in
the world,
main
ly
due
to its
limited
distribution
(Thor
bjarnarson
1992).
The
green
anaconda,
the
largest
snake
in
the
wor
ld,
is
commonly
found
during
the
dry
season
in t
he
hyper-
seasonal
savanna
of
the overflow plains.
The
arrau
or
giant
Amazonian
side-necked
turtle
is
another
giant
in
its group,
with
a
carapace
length
that
can
exceed 80 cm,
making
it
one
of
the
largest
freshwater
turtles
in
the
world.
The
giant
otter
is
the
long
est
otter
in
the
world,
and
similar
in
weight
to
the
North
Am
erica
n
sea
otter
(Enhydra
lutris).
Finally, we
hav
e
the
capybara,
one
of
the
mos
t con-
spicuous
flagships
of
the
Llanos,
and
the largest
rodent
in
the world.
The
Lla
nos
subspecies (Hydrochaeris.
hydrochaeris hydrochaeris) is
the
lar
gest
of
all,
reaching
at
l
east
79 kg
and
possibly as
much
as 90 kg.
These
abun
-
dant
semiaquatic
rodents
a
re
common
ly found a
lon
g
the
many
natural
channels
locally
known
as
cafios
chigii.ireros, a
nd
spend
most
of
their
time
in
the
mud
as
a
way
to
control
their
body
tempe
ra
tur
e.
Human
Cultures
The
2000
ce
nsus
showed
a total
of
15 719
indigenous
people, belonging to several
ethnic
groups, 1iving
in
rur
-
al
com
munities
within
the
Venezuelan
Llanos.
The
largest
group is
the
Karina,
with
an esti
mated
popula-
tion
of
7 253, followed by
the
Pume
(
or
Yaruro) with
5 321,
the
Warao
with
2 485,
the
Guahibo
with
333, the
Kuiva (or Cuiba) with 325,
an
d
the
Wa
yuu
with
only
two
individuals left.
The
Pume,
Guahibo,
and
Kuiva
occupy
the
southwestern
areas
around
the
Capanaparo
and
Cinaruco
Rivers,
and
support
themselves
mostly
by
fishing,
huntin
g,
and
traditional agriculture, with yucca
and
produce
bein
g
the
princip
al
crops
. Some
of
th
e
y
oun
ge
r
Pume
speak
Spanish
a
nd
occasionally travel to
populated
areas to work
as
c
rop
hands
or
other
season
-
al jobs,
but
mostly
these gro
ups
still live a traditional
subsistence
life-styl
e.
The
Karina
an
d W
ara
o
occupy
the
Eastern
high
plains,
the
la
tter
be
ing
the
pr
e
dominan
t
ethnic
group
of
the
Orino
co Delta,
and
show
varying
de
gre
es
of
acc
ultur
ation.
In
Colombia,
th
ere
are
11
indi
gen
ous
gro
ups
in
the
Ll
anos, the
vast
m
ajor
it
y
of
w
hi
ch
are
Sikuan
i.
Oth
ers
include
the
Cuia, Saliba, Tunebo, Macaguan,
Guah
ibo,
Piapoco, Guayabero, Curripaco, Betoy,
and
Piaroa.
The
total
population
is 23 556
and
they
inhab
it
a series
of
Indigenous
Reserves (R
esguardos
Indigenas)
cover
ing
2 818 182
ha
(Romero et al. 1993).
Based
on
proje
ctions
from
the
OCEJ (2000),
the
es
t
i-
mated
rural
population
of
the
Llanos in Venezuela is
714
691,
yielding a
human
density
of
2.6 inhabitants/
km
2.
In
Colombia,
the
rural
population
is 351 265, for a pop-
ulation de
nsi
ty
of
2.0 inhabitants/
km
2. Combining
these
figures,
the
total
popu
l
ation
for
the
Llanos
comes
to
1 065 956,
or
2.4
inhabitants
/
km
2.
Threats
One
of
the
greatest
threats
to
the
Llanos is
tha
t posed by
human-induced
fires. Although
many
plants
have
adap
-
tations to fire,
human
use
of
fire is
sometimes
extreme.
Fire is
used
mainl
y
in
two ways.
One
is
as
an
aid
in
hunting, to flush
animals
or
to utilize
those
killed by fire
(especially
by
nomadic indigenous people).
The
other
use
is
by
ranchers,
to
get a
"g
reen
bite"
for
their
cattle by burn-
ing large
areas
at a
much
h
igher
frequency
t
han
would
occur
naturally
.
This
increased
freque
ncy
of fires alters
floristic
compos
ition
and
favors
plants
th
at
are
p
ar
ticu-
larly
fire-resistant.
By far
the
most
common
econom
ic activity
in
the
Llanos
is
cattle ranching. Most
of
the
regi
on
is
in
th
e
hands
of
a few
catt
le
ranchers
who
own
huge
prop-
erties
ranging
from
10
000 to more
than
100 000 ha.
However, cattle exist at
very
low
densit
y,
us
ually 0.2-1
per
hectare,
and
an
im
als
range
freely,
fe
eding
on
nat-
ural
pas
t
ure
in
othe
rwise
pristine
la
ndscapes, moving
fr
om
banco to bajfo to estero as
the
d
ry
season
progress-
es,
and
b
ack
as the
savannas
flood again.
As
a result,
it
appears
that
the
impact
of
catt
le-
ranching
on
wildli
fe
is
fairly low
-a
situation
similar
to are
as
of
traditional,
extensive
catt
le
-ranching
in the Pantanal.
Some
ranches
ha
ve engaged
in
water
management
,
building dik
es
to
manipulate
the
water
flow
in
the savan-
na
and
minimize
the
impact
of
the
dry
season
,
thus
increas
in
g t
he
area
of
estero t
hat
retains wat
er
for l
onger
periods
over
the
yea
r
at
the
expense
of
th
e bajio,
and
alter
in
g
the
na
tur
al processes
of
both
ecoystems
. Si
nce
the Llanos tilt to the Eas
t,
pretty
much
every
road
that
runs
n
orth
to
south
has
the
poten
tial to act as a dike. As
a result,
the
lower-lyi
ng
lands
su
ffer
prem
ature
drou
ght
due
to t
he
water
se
queste
red
in
the
upper
p
ar
t
of
th
e
wat
e
r-man
agement
areas
or
m6dulos.
During
the
middle
of
t
he
dry
season,
the
gat
es
are
opened
for a
short
peri-
od
of
t
im
e (one
or
tw
o days) a
nd
the l
ower
m6dulos flood
again,
stimulating
the
growth of
the
pla
nts
there.
This
drainin
g
of
the
upp
er modulo allows a large
area
to
be-
come
somewhat
dr
y,
pe
rmitti
ng grass grow
th
to begin.
This
mana
ge
ment
conti
nu
es
throughout
the
dry
season
to provide
green
pasture
for cattle, despite
the
lack
of
rain.
When
the
wet
season
begins, the gates
are
opened
again a
nd
the
wat
er is
let
out
to
prevent
over
fl
owing
and
----
-----
breaking
of
the dikes.
Such
habitat m
an
ipulation
can
greatly
increase
the
production
of
cattle in
the
sava
nn
a.
However,
it is very expensive,
and
fortunately
on
ly
very
few
ranches
can
afford it. Most cattle operations
are
quite
simple and not very different from 400 years ago,
with
minimal
impact
on
the
ecosystem.
Fishing
in
the rivers
has
b
een
intense
near
the
popu-
lated
areas,
and
the
species
and
size-class composition
of
the different commercial species have
changed
over
the
last
15
years. However, this trend is less
important
in
more remote areas.
Agricu
lture is
even
less
of
a threat. Soils in
the
Llanos
are
heavy in texmre, acidic,
and
with low capacity for
cat
ionic exchange.
This
translates
into
very
poor
soils
w
ith
practically no potential for agriculture.
The
only
places where large-scale
commercia
l agricu
ltur
e is pos-
sib
le are next to
dams
(e.g. Calabozo
and
Acarigua,
Venezuela),
where
water
supply
is
re
liable. Even in
suc
h cases, it always requires large
amounts
of
pesti-
cides
and fertilizers,
making
it less profitable
and
more
pollutin
g.
On the riverbanks, conditions
are
different
du
e
to
regular flooding, whi
ch
allows soils to
be
lig
hter
and
river
sediments
to
enhance
fertility. Some agricul-
ture is possible in these areas, including cotton, corn,
and oth
er
produce.
However
, this
kind
of
agriculture
ca
n have a damaging impact
on
wildlife through frag-
mentation, since th
ese
riverbanks act as natural
corr
i-
dors
for
a
ll
forest-dwelling wildlife. Fortunately,
such
agri-
culture is not
yet
carried
out
on
a large scale,
being
mostly a small-scale family activity. Lack
of
roads
in
most
of
the
Llanos also makes all agric
ultur
al activi-
ties
less profitable.
Commercial logging
in
forested areas is a largely
uncontrolled
and
growing threat.
It
takes place
mainly
near the Andes,
where
most
of
the forests are located.
After
logging, areas
tend
to
be
rep
l
aced
by
pasture,
and
there are large areas
where
dr
y forest
once
existed
that
have
now
been
replaced
by
cattle ranches.
Exotic speci
es
are also a problem. Feral
domestic
ani-
ma
ls such as pigs, cats,
and
dogs
can
transmit
diseases
to
the native wildlife,
prey
on
smaller
an
imals,
or
com-
pete
for
habitat.
House
mice (Mus musculus)
and
rats
(Ra
ttus rattus) occur,
and
even
cattle
and
hor
ses
some-
times go feral and live
in
the
wild in vast
areas
called
cimanoneras.
The
m
ost
significant
impact
for native
ungulate species is the incidence
of
hoof
-and-mouth dis-
ease,
which
has
contributed
to
the
extirpation
of
entire
populations
of
white-tailed d
ee
r
and
peccary.
Some
Af
-
rican grasses
such
as Cynodon dactylon,
Digitaria
decum-
bens,
Hyparrh
enia rufa,
and
Urochloa mutica
with
high-
er nutritional value
than
the
local speci
es
, have also
been introduced for cattle.
Fortunatel
y, however,
there
are no reported cases
of
exotic species r
ep
lacing native
ones, and exotics are
st
ill considered a
minor
problem
co
mpared to
many
other
parts
of
the
world. Finally, as
in
the Pantanal,
there
has
been
-for
more
than
a
decade- a plan for a
major
hydrological project
that
wou
ld
make
the
Apure River fit for navigation by large
vessels for a
long
er
period
of
the
year.
Th
is wou
Id
involve building dikes
and
damming
the
river
, alleged-
ly decreasing the cost for
transporting
produce from
the Andes to the rest
of
Venezuela. However,
as
with
the
Hydrovia Project in Brazil,
such
an
undertaking
would
dramatically
alter
the
water
regime
and
ecology
of
the
western
part
of
the
Venezuelan Llanos. All species
would
be
affected, especially those
under
threat
such
as
the Orinoco crocodile
and
the
giant
Amazon river turtle,
which rely
on
the
seasonal draining
of
the
watershed
and
consequent
exposure
of
nesting
beaches
for repro-
duction.
The
social
impact
of
the project would also
be
dramatic
, since
many
populated
areas would flood.
Local conservation
groups
have oppo
sed
th
is
project
and
hopefully will c
ontinue
to
be
successful;
nonethe-
less, as with the Brazilian Hydrovia, it probably will
rear
its
ugly
head
from time to time in
the
future
-
making
it
necessary
for conservationists to
remain
ever
vigilant.
On
the
Colombian side, extensive oil
development
in
the
Llanos is a fairly
recent
threat
that
has
brought
with
it c
onstruction
of
access
roads
and
increased
pressure
on
the
natural resourc
es
of
the area.
The
threat
of
an oil
spfll into a
major
'vaterway is also
ever-present
, exac-
erbated
by
the vio
lent
activism
of
rad
ical political
groups; indeed, in
2000over120
pipelines were
bombed
in
different
parts
of
Colombia.
On
top
of
th
i
s,
efforts to
control guerrilla groups by
both
government
military
forces
and
paramilitary groups
sometimes
involve
powerful chen1ical
s,
such
as defoliants,
that
can
have
disastrous impacts
on
the
environment.
Since a
ll
Llanos
watersheds drain to
the
east, oil spills
and
other
sources
of
pollution
in
the
Col
ombian
Llanos have
the
po
t
ential
to
affect a large
area
extending
to
the
easternmost
reaches
of
the
Llanos
and
other
biomes
as
well.
Conservation
There
are
five national
parks
in
the
Venezuelan Llanos
covering a total area
of
1 257
618
ha. In add
it
ion to these,
there
are a
number
of
other
protected
areas, including
forest reserves, forested areas, wild
li
fe
refuges,
and
pro-
tected zones,
and
areas
of
integrated
development
,
which together add
up
to 6 099
274
ha
(Castillo
and
Gar-
cia 2000).
On
the
Colombi
an
side,
th
ere is
only
one
national park, Parque Nac
ion
al Thparro, covering
an
area
of
548 000
ha
. Together, the protected
areas
in
the
two c
ountri
es
total 6 647 274 ha,
representing
14.7%
of
the region
as
defined.
However, it is
important
to
note
that
most
of
the
gov-
e
rnm
ent-protected areas
have
little
if
any
mana
gement.
The
main
reason for the largely pristine condition
of
the
Llanos is the low
human
population
density, co
mbined
with the land t
enure
system
in which a few people
own
very large areas
where
low
impact, low
densit
y cattle-
ranchin
g is
the
principal land-use activity.
This
is
quite
similar
to
the
situation in
the
Pantanal r
eg
ion
of
Brazil,
Bolivia,
and
Paraguay.
Thes
e la
ndowner
s enforce strict
no-trespass
ing
rules
aimed
to
prot
ec
t
their
cattle,
but
wildlife also benefits.
On the opposite
pa
ge
and
above,
g
re
en anaconda (
Eunect
es
rnurinus)
, one
of
the wor/ri's
two largest snakes.
o
Tuny
Crocetta
/ BIOS
271
Above,
mother
and
juvenile
capyham
(Hydrochae
ris
hydrochaeris),
an
abundant
and
hi
g
hly
-visible flagship species
of
the Llanos that
is
also harvested
for its meat
in
some
pw·
ts
of
the region.
©
Tun
y
Crocetta
/ BIOS
On the following
pa
ge,
scarlet ibises (Eudocirnus
rub
er)
at
sunset in the Venezuel
an
Llanos.
"'
Luiz
C
laudio
Marigo
272
There
are
t
wo
kinds
of
commercial wildlife manage-
ment
in
the
Venezuelan
and
Colombian Llanos.
The
first
is a traditional
harvest
of
capybaras during Lent, follow-
ing a Papal Edict
permitting
use
of
such
meat
in
pl
ace
of
fish. For over
40
years, the Venezuelan
government
and
more
recently
the
Colombian as well, have authorized
cattle
ranchers
to commercially exploit
their
capybara
populations
at
this
time
of
year
(Ojasti
1991
).
This
prac-
tice was considered a sustainable use of the resource
and
many
ranches,
such
as
Ha
to
El
Frio, practiced it
on
a reg-
ular
basis.
However
, things
have
tak
en
a
turn
for
the
worse in
recent
years,
and
drastic declines
have
resulted.
In
Hato El Frio, for example, a population
that
had
once
numbered
between
30 000
and
45
000
had
drop
ped
to
barely
4 000 individuals
by
1986 (Ojasti 1978; J.
Ri
vas,
unpublished
data).
This
dramatic
crash
is
thought
to
be
the
result
of
increased
poaching driven by a declining
economy
following
the
drop
in
oil prices
in
1982. Nowa-
days, c
ap
ybaras can still
be
found
just
about
anywhere
in
the less-
populated
areas,
but
very
few
ranches
have
har
-
vestable populations.
The
other
commercial
har
vest
of
wildlife
in
the
Llanos involves spectacled
ca
i
mans
(Thorbjarnarson
1991
). After the
much
lar
ger
Orinoco crocodile was
hunt-
ed
out
in
the
1930s
and
1940s,
and
again
in
the
1970s,
the
spectacled
ca
i
man
took
over
the
habitat
formerly
occupied
by
the crocodile
an
d its
population
numbers
exploded.
The
harvest
of
wild
populations
for
the
leather
trade proved to be a profitable business,
and
man
y
ranches
started harvesting
their
caimans
.
The
harvest of
over
100 000
animals
per
year
was
considered
to
be
sus-
tainable
(Thorbjarnarson
and
Velasco 1999).
How
eve
r,
there
wer
e
many
flaws
in
the
im
pl
ementation
of
the
pro
g
ram
,
regulations
had
many
loopholes
,
and
the
pro-
gra
m h
as
shown
less
th
an
opti
mum
results. Unfo
rt
u-
nately
,
the
wildlife
protection
agen
cy
depended
on
ta
x
revenues
from
this
program ,
which
kept
it from
acting
rapidly to
prevent
over
exploitation. Skin prices
dropped
dramati
ca
lly
af
ter
1992 b
eca
us
e
of
in
c
reased
availabil-
ity
of
alligator
skins
from
th
e U.S.,
with
the
resu
lt
th
at
pressures
on
Llanos
caiman
populations
dec1ined
as
wel
l. Since
the
spectacled
caim
an is
such
a
resilient
species
,
it
is still
abundant
a11
over
the
Llanos. Howev-
er, as
with
the capybara,
only
a few r
anc
hes
have
pop
-
ula
tions
large
enough
to
sustain
a
commercia
l
ha
rvest.
While
ca
im
an l
eat
her re
venues
were
booming
(1986
to 1992), a large
numb
er
of
ranch
es
bui
lt facilities to
in
cuba
te
caiman
eggs co
ll
ected
from
the
wi
ld
and
kept
the
animals
lon
g
enoug
h to g
row
to a co
mmer
cially-
profitable size
(usua
lly
one
year).
Al
thou
gh
many
of
th
ese
operations
were
legitimate, there
we
re also
many
bo
gus far
ms
tha
t
har
veste
d a
nim
als from
the
wild
in
an
unsustainable
manner.
The
co
11
apse
of
leather
prices
drove
mo
st
of
these
operations
o
ut
of
business.
Tuday,
so
me
of
tl1ese facilities are b
eing
conside
red for com-
mer
cia
l
farming
of
the
Or
ino
co crocodil
e,
the
ski
n
of
which is far
mor
e va
lu
able.
How
eve
r,
since this
spe
cies
is
on
Appendix
I
of
CI
TES
.
only
second-gener
a
tion
an
i-
mals
born
in captivity can be sold,
and
those
supporting
exploitation
are
in
creasing
the
pr
essure
to downlist
the
Orinoco crocodile to
Appendix
II, so ran
chi
ng
and
har-
vesting
can
be
allowed.
Current
ly, populations
of
Ori
noc
o crocodil
es
have e
xper
i
en
ced
only a
ver
y mod-
est
recovery
after
mu
ch effort
and
mone
y have
been
invested
in
their
conservation
.
Consequ
ent
ly,
conser
-
vat
i
on
groups
in
Venezuela
strong
ly
oppose
downlist-
i
ng
, fearing
th
at
it might follow
the
slippery slope tak-
en by the
caiman
ranches
-with
disastrous
resu
lts for
a far
1e
ss
abundant
and
less
adaptab
le species
th
an
the
caiman.
Overall,
most
of
th
e Llanos is
st
ill
in
very
good con-
dition
and
we
estimate
that
approx
im
ately
80
% re
mains
in
wilderness
state
. Although
most
of
it is
be
ing
or
has
been
used
for cattle
ranch
ing,
the
in
ten
sity
of
the
oper
-
ation
is
such
that
t
he
imp
act
on
the
habitat is very mil
d.
In
some
places
where
human
densit
y is
higher
, there
have
been
local extinctions,
bu
t
this
trend
disappears as
one
moves
away from
the
cities. Major modifications to
the
environme
nt,
such
as
dams, dikes,
and
deforesta-
tion
,
have
fortunately
not
yet
taken
a large toll
on
t
hese
vast plains,
and
the
low
human
dens
ity
over
most
of
the
area
prevents
ot
her
significant i
mpac
t
s.
Overall,
ther
e is
great
hope
for
th
is
wilderness
to re
main
bas
ically
unchanged,
at
l
east
for
the
t
ime
being.
J ESUS
RI
VA
S
JOSE
VI
CENTE
RODR
IGUEZ
CR
JS
TlNA
G.
MI
TTERMEIER
... Anacondas and other boids are listed in CITES Appendix II, which requires permits be obtained for any commercial trade. In Venezuela, anacondas remain abundant due to large expanses of relatively undisturbed wetland habitats (Rivas et al. 2002). No legal commercial trade exists, and the illegal market for skins places little pressure on populations at the moment. ...
... Habitat degradation in the llanos has not yet been a serious problem, since most land use for cattle involves increasing the area covered by water for longer periods (Rivas et al. 2002). The impact of extensive cattle ranching on wildlife here is much lower than the impact in the United States or other countries where cattle are kept at higher densities. ...
... En Colombia, las poblaciones silvestres más abundantes de chigüiros se encuentran en algunas propiedades privadas en las sabanas inundables semi e hiperestacionales de la Orinoquía. En el país, la explotación comercial de chigüiros existe desde 1935 (Ojasti 1973); sin embargo, ésta se realiza principalmente para abastecer los mercados venezolanos, donde el consumo de carne está relacionado a una tradición religiosa (Ojasti 1973, Herrera 1999, Ojasti 2000, Rivas et al. 2002. ...
... La zona de estudio se encuentra a una altitud promedio de 300 msnm y se caracteriza por presentar una marcada estacionalidad climática, Modelo de simulación de la dinámica de poblaciones silvestres de chigüiros Hydrochoerus hydrochaeris en el departamento de Casanare Elizabeth Mesa-González, Hugo Fernando López-Arévalo, Pedro Sánchez-Palomino & Clara Inés Caro con una época lluviosa de ocho meses entre abril y noviembre y una época seca de cuatro meses de diciembre a marzo (IAvH 2004). Durante la época húmeda debido a las lluvias torrenciales, el suelo se satura y se cubre con una lámina de agua (Cavelier et al. 1996) que anega la sabana, mientras que durante la época seca hay una prolongada sequía que causa intensos fuegos naturales y la reducción de las fuentes de agua, aunque en ocasiones permanecen solo algunas lagunas y esteros (Rivas et al. 2002). La temperatura media anual es de 26 o C y la precipitación varía entre 1500 mm y 2500 mm anuales (IAvH 2004). ...