Ecología de los Chivos Ferales (Capra hircus) en el Volcán Alcedo. Ecology of Feral Goats (Capra hircus) on Alcedo

Volcano. Pepino War, 1992

Merlen, Godfrey

Muñoz, Edgar

English

Aquatic Commons

2 NOTICIAS DE GALAPAGOS No. 52
NEWS FROM ACADEMY BAY
Ecología de los Chivos Ferales (Capra hircus)
en el Volcán Alcedo.-En la Isla Isabela hasta hace
12 años, la distribución de los chivos ferales se re-
stringía sólo al Volcán Sierra Negra. Sin embargo, en
los últimos 4 años la migración y colonización se
incrementó rápidamente hacia el norte de la Isla.
Actualmente los chivos están ocupando diversas áreas
del Volcán Alcedo. Consecuentemente, los efectos
ecológicos que pueden ocasionar estos herbívoros
pueden ser extremadamente devastadores con la in-
minente destrucción de la cobertura vegetal, erosión
del suelo, probable extinción de especies de plantas
nativas y endémicas y la eventual competencia por
alimento y hábitat con la mayor población de
tortugas terrestres (Geochelone elephantopus van-
denburghi) del Archipiélago (3 a 4,000 individuos).
Con estos antecedentes y buscando información que
permite especializar los métodos de control, manejo,
y erradicación de chivos se realizó durante 1991 un
estudio sobre la distribución, estructura poblacional,
área de vida, ciclo reproductivo, y comportamiento
alimenticio entre otros de los chivos.
Los chivos en el Volcán Alcedo están distribuidos
en el Sur, lados Este, y Suroeste del mismo. Grupos
esporádicos se localizan en las costas con tendencia
general de migrar y ocupar la parte norte del Volcán.
Las migraciones más representativas de las pobla-
ciones de chivos se dan en la época de garúa o de frío,
debido principalmente a la falta de agua y de alimen-
to. Existen solamente tres grupos de chivos en el cráter
y uno en el Suroeste del Volcán, con un promedio de
18.2 individuos/rebaño. El tamaño y composición de
los rebaños no varia con las estaciones climáticas. El
área de vida de los chivos en el Volcán fue de 1.3 km2,
el área ocupada por las hembras fue mayor que la de
los machos pero no difieren significativamente en
ninguna época del año. Los chivos se reproducen
durante todo el año, con picos de reproducción en la
época de calor. Solamente de cinco especies de plan-
tas se alimentan los chivos, siendo la más frecuente
Blainvillea dichotoma (Compositae). Existe compe-
tencia por la disponibilidad alimento y espacio entre
los chivos y tortugas, especialmente en la época de
frío. Se incrementó grandemente el rendimiento, efi-
cacia de la cacería con el uso de radiotelemetría y con
la información obtenida. Esto permite planificar es-
trategias de diferentes niveles para el control y el
posible exterminio de esta especie en el Volcán. Edgar
Muñoz, Estación Científica Charles Darwin, Isla
Santa Cruz, Galápagos, Ecuador.
Ecology ofFeral Goats (Capra hircus) on Alce-
do Volcano.- Twelve years ago, on Isla Isabela the
distribution of feral goats was restricted to Sierra
Negra Volcano. However, within the last 4 years,
migration to and colonization of areas to the north
increased rapidly and goats are now found on Alcedo
Volcano. The ecological effects that these herbivores
can cause could be devastating, with destruction of
the vegetative cover, soil erosion, possible extinc-
tion of native and endemic plant species, and
competition for food and space with the largest pop-
ulation of giant tortoise (Geochelone elephantopus
vandenburghi) in theArchipelago, numbering 3,000-
4,000 individuals.
Given this background and a literature search that
allowed specialization in the methods of control,
management, and eradication of goats, a study was
conducted in 1991 on the distribution, population
structure, home range, reproductive cycle, and feed-
ing behavior of the goats.
The goats on Alcedo Volcano are distributed in
the southern, eastern, and southwestern flanks. Spo-
radic groups are found on the coasts and have a general
tendency to migrate towards and occupy the north-
ern part of the volcano. The most representative
migrations of the goat population occur in the garúa
or cold season, due principally to the lack of water
and food at this time. Only three groups of goats
occur in the caldera and one in the southwest of the
volcano, with an average of 18.2 individual sper herd.
The size and composition of the herds do not vary
with the seasons. The home range of the goats on the
volcano averaged 1.3 km2. Females averaged larger
home ranges than males although the difference was
not significant in either season of the year. Repro-
duction occurred throughout the year, with peaks in
the hot season.
May 1993
.1
NOTICIAS DE GALAPAGOS 3
Only five species of plants were recorded as being
consumed by goats, with Blainvillea dicho toma
(Compositae) being the most frequentl y eaten. There
is competition for food and space between goats and
tortoises, especially during the cold season.
The yield and efficiency of hunting efforts in-
creased gready with the use of data obtained with
radiotelemetry. Theinformation gained from the study
will permit the planning of strategies for the control
and possible elimination of goats fromA1cedo Vo1ca-
no. Edgar Muñoz,Charles Darwin Research
Station, Isla Santa Cruz, Galápagos, Ecuador.
(Translated by Gayle Davis-Merlen.)
Pepino War, 1992.-If 1 had been bom in the
Guasmo of Guayaquil, into the abject poverty that
occurs there, into a world of harsh survival, into a
world without trinkets and fancy toys such as televi-
sion, Betamax, and gaudy c1othes, 1would jump with
glee to be offered ten thousand sucres a day to pick
animal sfrom the sea floor, to be able tojoin the wealthy
elite gaining the power to buy my own baubles and
vodka and Nikei!!Jshoes.
Thus it was that people were drawn to the black
shores of the western islands of Galápagos in search
of a fortune lining the floor of the ocean, their pathet-
ic camps gaining a toehold on the harsh shoreline
under a brilliant sun. It sparked a war between the
conservationists, most of whom probably had their
vodka and Nike shoes, and the entrepreneurs and em-
ployees of the ill-conceived plan to rashl y overexploit
a resource, sea cucumbers, or "pepinos del mar," in
one of the world's most famous archipelagos.
It was, in the end, after accusations, threats, and
anger, a victory for the conservationists. Stumps of
cut mangroves will now be healing. Endemic rice
rats on Fernandina will hop, kangaroo-fashion, dur-
ing the dawn and dusk under the brooding vo1cano,
temporarily free from the imminent threat of extinc-
tion by the accidental introduction of exotic rats by
people unaware of the damages rats cause. The trea-
sure seekers have returned, bankrupt, to the Guasmo.
And ,wewill sit down to sip our vodka and remove our
new Nike shoes from our tired feet. Godfrey Merlen,
Isla Santa Cruz, Galápagos, Ecuador.
Editor's Note.-Godfrey Merlen's graphic prose
refers to one of the most recent face-offs between
commercial pressures to allow unlimited harvest of
natural resources and the desire to conserve Galápa-
gos ecosystems. The conflict comes from economic
desires to exploitresources in Galápagos risking major
ecological perturbations versus the goal of preserv-
ing Galápagos for all of Ecuador and humanity by
limiting commercial exploitation of resources to lev-
els and uses that are sustainable and compatible with
conservation of the terrestrial and marine ecosystems.
In contrast to the long-term, ongoing management
studies conducted in the terrestrial environment by
the Servicio Parque Nacional Galápagos and the
Charles Darwin Research Station, little is known about
the potential sensitivity of Galápagos marine com-
munities tocommercial exploitation. While the batdes
between entrepreneurial and conservation interests
will continue, c1early more scientific studies are need-
ed in this environment before commercial activities
can be safely permitted. [THF]
..-


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