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Los Llanos Habitat Project, Venezuela
Guy Baldassare, Coordinator
The Llanos
Set in a vast, flat, sedimentary plain that
borders the Orinoco River and its tributaries, the Llanos region of
Venezuela and Colombia represents one of
the largest wetland complexes in the world. In Venezuela, almost
6 million acres (24,000 km2) approximately 26% of the total national
territory, lie in the Llanos, of which over 2.4 million acres (10,000
km2) are wetlands. These are divided into the eastern and western
Llanos, the latter of which is especially subject to flooding and is
located in the states of Apure, Barinas, Portuguesa, Cojedes and
Guarico. The Llanos lies 100-120 meters above sea level and can be
roughly divided into upper and lower regions, situated to the north and
south of the river Apure respectively. The entire region has pronounced
phases of drought and flood with seasonal rains (May-Sept) turning much
of the landscape, particularly in the low Llanos, into an immense
inland lake as rivers overflow their banks and water accumulates in
depressions. By contrast, the dry season is so severe that fauna,
particularly birds, become highly concentrated in places of remaining
water, which creates an amazing wildlife spectacle. With the arrival of
rains, plants start growing again and fauna disperses throughout
landscape. Due the extremes of inundation and drought, the region is
best described as a hyperseasonal savanna, although there are a variety
of habitats in what is a complex, heterogeneous landscape.
In
the low Llanos soil fertility is generally low and unsuitable for
agriculture, and population density is less than 5 people per km2.
Nearly all land is in private hands with the existence of ranches
(Hatos) mostly dedicated to cattle rearing, some in excess of 247,000
acres (100,000 hectares). Some of these Hatos promote ecotourism, and  hence
function as wildlife refuges. Since the 1950s, many raised dikes
(Módulos) were constructed to retain water into the dry season to aid
cattle grazing, and these dikes have influenced traditional drainage
patterns, particularly in the low llanos. Road construction also
accelerated to connect the thinly spread population centers, many of
which were previously only accessible during the wet season by boat. A
consequence has been the creation of thousands of borrow pits flanking
the roads, which retain water through the year and attract wildlife.
The upper Llanos historically had a greater cover of forest, but in the
last 40 years much land has been cleared, drained, and converted to
agriculture, particularly rice, maize and sorghum. The most important
wetland sites of the western Llanos are the "Módulos de Apure" (Apure
Modules), "Esteros de Camaguán" (Camaguán Marshes), the central and
western low Llanos, and the palm savannas of the eolic flat in the
south of Apure.
Fauna
Blue-winged teal, (Anas discors) are the only migratory North American waterfowl to reach the Llanos in significant numbers, with White-faced (Dendrocygna viduata) and Black-bellied (D. autumnalis) whistling ducks the most abundant and widespread species. Other waterfowl of note include the Brazilian Teal (Amazonetta brasiliensis), Orinoco Goose (Neochen jubata) (endangered), Muscovy Duck (Cairina moschata) (endangered) and Comb Duck (Sarkidiornis melanotos)
(endangered). Principal other groups of waterbirds are ibis (7
species), storks (3 species) and herons (more than 15 species). One of
the most charismatic species is the endangered scarlet ibis (Eudocimus ruber), of which 90% of the total population is estimated to live in the region. Also significant are the Sharp-tailed Ibis (Cercibis orycerca) (vulnerable), Roseate Spoonbill (Ajaia ajaja) (endangered), Wood Stork (Mycteria americana), Maguari Stork (Ciconia maguari) (endangered) and the Jabiru Stork (Jabiru mycteria) (threatened), the largest flying bird in the Neotropics. In total, over 70 species of waterfowl and waterbird are present!
The Llanos also has significant populations of capybara (Hydrochaeris hydrochaeris), jaguar (Panthera onca), ocelot (Felis pardalis), giant anteater (Myrmacophaga tridactyla), river dolphin (Inia geoffrensis), manatee (Trichechus manatus), giant river otter (Pteronura brasiliensis) and the Orinoco crocodile (Crocodylus intermedius), which is the focus of an active recovery program.
Threats
In
the low Llanos, the traditional low intensity cattle ranching does not
impact greatly on the environment but conversion of land to agriculture
in the upper llanos has led to the drainage of wetlands, soil erosion,
silting of rivers, and contamination from pesticides and fertilizers.
Growing populations and industries at the edge of the Llanos release
domestic and chemical waste into the rivers that drain through it, and
since 1990 intense oil exploration has seen contamination of
watersheds. Increased road construction also encourages people into the
region, but perhaps more significant are current land reform proposals
to take underutilized land from the larger Hatos and give it to people
who will be actively resettled in the region, potentially reducing
their influence as wildlife refuges. In addition, the "Cuenca
Orinoco-Apure" project is actively under consideration, which aims to
make the Apure, which flows through the heart of the Venezuelan Llanos,
navigable to commercial vessels and allow their passage from the
Atlantic, via the Orinoco, to Colombia. Associated with this are plans
to dam many of its tributaries to provide water for release during the
dry season and maintain water levels, which may have a serious impact
on natural flooding cycles throughout the region.
Specific
threats to waterbirds include the unregulated subsistence hunting of
most species, including the storks and larger herons, which is directly
related to a decline in economic stability since the 1980s. Hunting of
waterfowl is also widespread, and is particularly intense in rice
growing regions where whistling ducks are a significant consumer of
crops. During November-December, whistling ducks molt all their flight
feathers and are flightless for three weeks. At this time large numbers
are traditionally corralled and captured. The disturbance of breeding
colonies of ibis and storks to remove chicks and eggs has also been a
significant problem, sometimes resulting in entire sites being
abandoned.
Aims of this project
Despite the size and
significance of the Llanos wetlands, there have been no large scale,
systematic studies to map and monitor changes in land use nor quantify
waterbird populations, which are believed to be declining. This project
aimed to address both and simultaneously develop in-country expertise.
First, through the development of a GIS database which would classify
Llanos habitat from satellite images and other sources to provide a
sound tool for resource management. Second, by developing and
implementing a standardized monitoring protocol for waterfowl and
waterbirds to provide baseline data that would allow the statistical
analysis of population trends. Ultimately the GIS database will be
combined with the waterbird data to identify landscape level factors
influencing their distribution and abundance and make management and
conservation recommendations. The finished product will be a robust and
cost effective monitoring program combined with a GIS database that can
be continued and developed by organizations within Venezuela.
Progress
 Fieldwork
in Venezuela to monitor waterbirds commenced in July 2000, and
continued to July 2002 to establish a baseline dataset. Seven regions
within the western Llanos were selected as sentinel sites
representative of the range of habitats found in the Western Llanos in
which 54 transect routes, each 22.5 km in length, were established and
sampled at intervals of three months to coincide with changes in the
hydrological cycle. In total over 100 species of birds were recorded,
and although the emphasis was on waterfowl and waterbirds, coverage was
comprehensive and included other groups of interest such as parrots and
raptors. A GIS database was developed with the acquisition of
Landsat 7 images covering the Western Llanos and the classification of
habitats.
Cooperators and partners:
USDA Forest Service
Ducks Unlimited Inc.
The State University of New York - College of Environmental Science and Forestry, Syracuse, New York
US Geological Survey Cooperative Fish and Wildlife Unit, Mississippi State University
US Fisheries and Wildlife Service, Office of International Affairs, Washington, D.C.
Universidad Experimental de Los Llanos, Ezekiel Zamora (UNELLEZ), Guanare, Venezuela
BioCentro, Venezuela
ProFauna, Venezuela
ProVita, Venezuela
Audubon Society, Venezuela
Universidad Central de Venezuela, Venezuela |
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