ArticlePDF Available

Conservation Status of the Argentine Boa Constrictor (Boa constrictor occidentalis) 20 Years After Being Listed in CITES Appendix I

Authors:
  • Fundacion Biodiversidad - Argentina
  • FUNDACION BIODIVERSIDAD, ARGENTINA

Abstract and Figures

Twenty years after the species was listed in CITES Appendix I, we carried out a comprehensive review of the conservation status of the Argentine Boa Constrictor (Boa constrictor occidentalis) in Argentina. We compiled background information on trade, biology, and distribution. We evaluated the historical range on the basis of museum and literature records, and later adjusted it to incorporate environmental variables. We carried out 573 interviews with local residents regarding the historical presence of the species and the ways in which it was used. Using a rapid assessment of woody vegetation cover, we estimated the degree of habitat loss in Argentina. We conclude that CITES has been very effective in stopping the international trade and almost completely eliminating hunting pressure on this snake throughout Argentina. However, suitable boa habitat has been reduced by one third to approximately 30 million ha from a historical extent of occurrence of about 42 million ha in the Dry Chaco ecoregion. Loss of suitable habitat is mainly due to recent expansion in agricultural and livestock production. This subspecies is still common throughout its range; however, recent trends in habitat loss led us to conclude that the Argentine Boa Constrictor meets at least one of the CITES criteria for retention in Appendix I, at least until the recently enacted forest protection law proves its effectiveness in protecting the remaining Chaco forests of Argentina.
Content may be subject to copyright.
IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
ever, recent trends in habitat loss led us to conclude that the
Argentine Boa Constrictor meets at least one of the CITES
criteria for retention in Appendix I, at least until the recently
enacted forest protection law proves its effectiveness in pro-
tecting the remaining Chaco forests of Argentina.
Boa constrictor is the most widely distributed boid in the
Americas, where it occupies plains, foothills, and intermon-
tane valleys from northern Mexico to central Argentina,
including numerous coastal islands in the Caribbean Sea
and Pacific Ocean. Within this area, it occurs in all countries
except Chile and Uruguay. The species’ range extends across
66 degrees of latitude, 22 vegetation zones, and 11 morpho-
climatic domains, making it first in terms of ecological plas-
ticity in comparison to other boids and in relation to the
majority of American species of snakes (Waller and Micucci
1993, Henderson et al. 1995).
The taxonomy of Boa constrictor is problematic. Around
fourteen subspecies have been described to date, mostly on the
basis of weak diagnostic characters (Peters and Orejas-Miranda
Twenty years after the species was listed in CITES
Appendix I, we carried out a comprehensive review of
the conservation status of the Argentine Boa Constrictor
(Boa constrictor occidentalis) in Argentina. We compiled back-
ground information on trade, biology, and distribution. We
evaluated the historical range on the basis of museum and lit-
erature records, and later adjusted it to incorporate environ-
mental variables. We carried out 573 interviews with local
residents regarding the historical presence of the species and
the ways in which it was used. Using a rapid assessment of
woody vegetation cover, we estimated the degree of habitat
loss in Argentina. We conclude that CITES has been very
effective in stopping the international trade and almost com-
pletely eliminating hunting pressure on this snake throughout
Argentina. However, suitable boa habitat has been reduced
by one third to approximately 30 million ha from a histori-
cal extent of occurrence of about 42 million ha in the Dry
Chaco ecoregion. Loss of suitable habitat is mainly due to
recent expansion in agricultural and livestock production.
This subspecies is still common throughout its range; how-
Conservation Status of the Argentine Boa
Constrictor (Boa constrictor occidentalis) 20
Years After Being Listed in CITES Appendix I
Tomás Waller, Patricio A. Micucci, Mariano Barros, Juan Draque, and Candelaria Estavillo
Fundación Biodiversidad–Argentina, Juncal 754, 7th Floor Apt. 60, 1060 Buenos Aires, Argentina (twaller@fibertel.com.ar)
During the winter, boas usually are found perching in the low branches
of shrubs near mammal burrows; Fortín Soledad, Province of Formosa.
Photograph by Mariano Barros.
Young individuals of the Argentine Boa Constrictor usually exhibit dots on
their backs that are paler than those of adults — and sometimes even pink.
Photograph by Tomás Waller.
1
IRCF REPTILES & AMPHIBIANS • 4 • DEC 2008
190
198
204
212
220
223
The “Dow Jones Index” of Biodiversity 225
Captive Care of the Central Netted Dragon 226
234
238
edited by S.N. Stuart, M. Hoffmann, J.S. Chanson, N.A. Cox,
243
245
247
248
251
252
IRCF
REPTILES & AMPHIBIANS
C O N S E R V AT I O N A N D N A T U R A L H I S T OR Y
Copyright © 2012. Tomás Waller. All rights reserved.
WWW.IRCF.ORG/REPTILESANDAMPHIBIANSJOURNAL
2
WALLER ET AL. IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
An adult female Argentine Boa Constrictor (Boa constrictor occidentalis) subduing a Crab-eating Fox (Cerdocyon thous), Province of Salta, Argentina.
Photograph by Hugo Hulsberg.
IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
3
WALLER ET AL.
1970, 1986; Langhammer 1983; Price and Russo 1991); only
eight or nine of the subspecies are consistently recognized,
and some authors have suggested these be considered full spe-
cies (i.e., Boa nebulosa and B. orophias; Price and Russo 1991,
Binder and Lamp 2007, Bonny 2007, Daniells et al. 2008,
Henderson and Powell 2009). Hynková et al. (2009), using
mitochondrial DNA to discern the phylogenetic relationships
among six continental subspecies, suggested that two distinct
clades existed, and proposed a division into at least two addi-
tional species, Boa constrictor from mainland South America
east of the Andes and Boa imperator to the north and west of
the Colombian Andes through Central America and México.
Their conclusions, however, must be considered tentative,
since they were based solely on a partial mitochondrial gene
obtained mostly from captive animals.
The Argentine Boa Constrictor (Boa constrictor occiden-
talis) represents the southernmost taxon in this complex,
inhabiting the Great Chaco region from Paraguay to central
Argentina and presumably Bolivia (Waller et al. 1995, Di
Cola et al. 2008). Chébez et al. (2008) suggested that, due to
morphology, distribution, and ecology, this subspecies should
be re-elevated to full species status as originally described
(Philippi 1873). This subspecies did exhibit the most distinct
haplotype within the South American Boa constrictor clade in
the study by Hynková et al. (2009).
With a maximum size of about 3 m in total length, the
Argentine Boa Constrictor is undoubtedly the most conspic-
uous terrestrial snake in Argentina. It is present in the cul-
ture of the local human communities that share its habitat.
Traditionally hunted by local inhabitants for its fat, to which
medicinal properties are attributed (Bolkovic 1999), it also
has been exploited on a large scale due to the high value of
its skin, which is used in manufacturing fine leather goods
(Gruss and Waller 1988).
In 1987, at the Sixth Meeting of the Conference of
the Parties to the Convention on International Trade in
Endangered Species of Wild Fauna and Flora (CITES)
(Ottawa, Canada), B. c. occidentalis was listed in Appendix
I of this Convention. As a result of this listing, commercial
international trade was banned.
After 20 years of CITES Appendix I listing, Fundación
Biodiversidad–Argentina, under the supervision of the
An old “1980s” Boa constrictor occidentalis bag. The fashion industry is
no longer the main threat to Argentine Boa Constrictors. Photograph by
Tomás Waller.
We surveyed about 600 rural inhabitants throughout the boa’s range in
Argentina to evaluate presence or absence and local uses. Photograph by
Juan Draque.
The Argentine Boa Constrictor (Boa constrictor occidentalis) can attain total
lengths to 3 m and masses to 18 kg; Guadalcazar, Province of Formosa.
Photograph by Tomás Waller.
4
WALLER ET AL. IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
CITES Secretariat and the CITES Management Authority
of Argentina, conducted a full assessment of incidental trade,
current range, and habitat trends, to determine the conserva-
tion status of B. c. occidentalis in the country. Here we sum-
marize the most important results included in the full report
to the CITES Secretariat (Waller et al. 2010).
Methods
The survey initially involved a compilation of background
information on specific and general references to the
Argentine Boa Constrictor and its habitat, the international
trade in skins and live specimens recorded in the WCMC/
UNEP CITES Trade Data Base, and a review of available
information from various herpetological collections.
Subsequently, we initiated a detailed analysis of histori-
cal records relating to environmental and landscape variables
aimed at proposing an area of distribution or historic range
based on natural boundaries. Using extensive field surveys, we
proceeded to test and adjust the distribution map. The field
activities, carried out during a period of one-and-a-half years,
included nearly 600 interviews with rural inhabitants to check
for the historical presence (or absence) of the Argentine Boa
throughout its entire range in the country, obtaining infor-
mation on its habitat, and assessing the value of this snake to
rural communities.
In order to evaluate habitat trends, we estimated the loss
of woody plant cover in the species’ distribution. Taking
into account the area and the fine scale needed, we based our
analysis on Terra Satellite coverage published online by the
NASA Rapid Response System (http://lance.nasa.gov/imag-
ery/rapid-response/). These automatic mosaics reflect satis-
factorily the natural discontinuities in woody cover and the
anthropogenic transformation of crop and pasture land, with
the advantage of being updated on a daily basis. The aim
was not to generate a detailed vegetation map, but instead to
roughly estimate the loss of continuity in the natural vegeta-
tion within the boa’s historical range throughout Argentina.
Trade and Other Uses
According to our review of CITES trade statistics, Boa con-
strictor (sensu lato) is the snake species in the Americas that has
contributed most to global trade, involving both live speci-
mens and skins. About 393,000 skins and 630,000 live speci-
mens of this species were traded in the 29-year span between
1980 and 2008. Commercial trade in skins, mainly to meet
the demand from the United States and Italy, soared to tens of
thousands of skins per year, particularly over the first decade
analyzed (1980–1989). However, following the Appendix I
listing of the subspecies B. c. occidentalis in 1987, international
trade rapidly decreased to such an extent that reported trade in
B. constrictor (sensu lato) skins from 1990 onward represented
less than 1% of the total trade compiled in the CITES data-
base for the entire period (1980–2008; Fig. 1).
Most of the skins reported as B. constrictor (sensu lato)
in CITES trade statistics originated in Argentina, probably
as a result of lax CITES enforcement in the country at that
Argentine Boas were a source of income to poor rural inhabitants before
the international skin trade was completely stopped by CITES Appendix I
listing in 1987. Photograph by Tomás Waller.
Fig. 1. World net trade in whole skins of Boa constrictor (sensu lato)
between 1980 and 2008. Commercial trade diminished almost completely
after the listing of B. c. occidentalis in CITES Appendix I (Source: CITES
Trade Data Base).
IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
5
WALLER ET AL.
time, and in Paraguay, which was a source of documentation
of dubious legality during the 1980s (Waller and Micucci
1993). That B. c. occidentalis was the main subspecies in
the trade should not be surprising, especially since the local
media already expressed its concerns very early in the previ-
ous century about the potential impact of the snakeskin trade,
demonstrating that a commercial network for the subspecies
was well established in Argentina as early as the 1940s (Berst
1944, 1947; Llanos and Crespo 1952; Freiberg 1954, 1980;
Godoy 1963; Astort 1984; Gruss and Waller 1986, 1988;
Waller 1987a, 1992).
On the other hand, CITES statistics show that Argentina
did not play a significant role in the international trade of live
specimens, with only 1,612 individuals exported in 29 years
(1980–2008) compared to the 637,922 snakes exported from
Central American countries and, more recently, Colombia
during the same time span (Fig. 2).
According to responses to our inquiries during the field
surveys, the Argentine Boa Constrictor has no commercial
value throughout most of its range. Certainly, CITES has been
very effective in reducing and almost completely eliminating
hunting pressure on these snakes in Argentina and, very likely,
in the rest of its range. An occasional and small-scale level of
utilization remains in some localities, based on the use of its
fat as a traditional medicine and because of the existence of
an illegal but rudimentary internal market for skins and live
animals (Fig. 3). Skins are sold along routes in the central
Argentine Boas, Tegu lizards (Tupinambis rufescens), and Chaco Tortoises
(Chelonoidis petersi) are usually offered for sale along major roads in central
Argentina. Photograph by Tomás Waller.
Fig. 2. World net trade in live specimens of Boa constrictor (sensu lato)
between 1980 and 2008. Most of the trade involves B. c. imperator from
Central American countries and Colombia (Source: CITES Trade Data
Base).
Fig. 3. Localities in central Argentina where inhabitants reported no com-
mercial hunting of Boa constrictor occidentalis for skins (open dots), and
localities where inhabitants reported occasional hunting for skins (black
dots). Villagers in all the localities visited acknowledged having hunted
boas in the past.
6
WALLER ET AL. IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
Province of Santiago del Estero as souvenirs for tourists and to
supply a small local demand for leather goods in some cities.
Live snakes are occasionally sold illegally at public fairs and in
pet stores in big cities like Buenos Aires. Despite occasional
efforts at smuggling on a larger scale (e.g., www.news.com.au/
travel/news/snakes-on-a-bus-argentina-nabs-wildlife-trafficker/
story-e6frfq80-1226036739802), we consider that none of
these activities represent a significant risk to the survival of the
species in Argentina.
Historical Range and Habitat Trends
As a result of our review, the presence of B. c. occidenta-
lis was confirmed in 13 of the 23 provinces of Argentina.
Furthermore, we estimated that the species’ historical extent
of occurrence (sensu IUCN 2001) covered approximately
42.3 million ha, equivalent to 15% of the country’s main-
land territory (Fig. 4). Boa constrictor reaches its southernmost
limit of distribution on the continent at 33°20’ S latitude in
the province of San Luis, Argentina.
The Argentine Boa Constrictor almost exclusively inhab-
its woody areas of what is known as the Dry Chaco region
(Chaco Seco according to Burkart et al. 1999) to an altitude
of approximately 900–1,000 m above sea level, and in zones
with yearly seasonal rainfall (spring to summer) of 250–900
mm. It is absent or very rare at higher elevations (>1,000 m)
or in areas with annual rainfall in excess of 900 mm (i.e.,
Yungas rainforest), winter flooding (i.e., Humid Chaco), or
where soil constraints (salt marshes, rocky outcrops, water
bodies) interrupt typical Dry Chaco forest physiognomy.
This boa shows a remarkable ecological plasticity that
manifests itself in its ability to live in 20 of 22 terrestrial eco-
system complexes (sensu TNC et al. 2005) within the Dry
Chaco. Not surprisingly, boas are able to persist in degraded
environments, provided that the area maintains the presence
of woody plants and scattered trees with a minimum thresh-
old of heterogeneity to meet their needs for shelter and food
(Waller et al. 2010). However, the Argentine Boa Constrictor
cannot occupy grass- or crop-dominated cultural landscapes
unless the habitat is part of a more complex spatial matrix
that includes patches of typical woody vegetation. In effect,
today’s main threat for this subspecies is no longer exploita-
tion for food, hides, or pets, but habitat loss and fragmen-
tation the shrinkage of its range as a result of land use
changes to agriculture and livestock rearing.
Local effects of habitat fragmentation have been the
focus of recent research in the Province of Córdoba in central
Argentina. Although no evidence of inbreeding or significant
levels of genetic differentiation were found in two boa popu-
lations studied in fragmented habitats, this was attributed to
the relatively recent history of habitat conversion in the area
(Rivera et al. 2005, 2006). Furthermore, Rivera et al. (2006)
Fig. 4. (A) Presence records (red dots) versus absence records (yellow dots)
in relation to major habitat types in Argentina (Burkart et al. 1999). Records
obtained from museum collections, literature, and reliable interviews show
that Boa constrictor occidentalis occurs almost exclusively throughout the
woodlands of what is known as the Dry Chaco region to elevations of 1,000
m above sea level (asl). (B) The estimated extent of occurrence (sensu IUCN
2001) of B. c. occidentalis in Argentina after excluding major woodland dis-
continuities (i.e., salt marshes, river floodplains, and elevations above 1,000
m asl) covers about 42 million ha within the Dry Chaco region.
IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
7
WALLER ET AL.
found a high degree of gene flow among studied popula-
tions, which they attributed to the high dispersal capability
of males. However, a subsequently detected decrease in gene
flow (Cardozo et al. 2007) could be the result of a progressive
increase in habitat isolation. Strong differences in important
life history traits (e.g., size, body condition, and reproduc-
tive output) in relation to habitat complexity have also been
observed, and the long-term viability of boa populations at
these locations is a matter of concern and the subject of ongo-
ing research (e.g., Cardozo and Chiaraviglio 2008, 2011).
According to our study, the clearing and replacement of
forests and shrublands by crops and land for livestock rearing
is responsible for a 29% decrease in the historical range of B.
c. occidentalis in Argentina. Its current potential occupation
area covers 30.2 million ha, some 12 million ha less than its
historical potential (Table 1). Twenty percent of the identi-
fied habitat contraction is the result of changes in land use
that occurred during the past decade. In absolute terms, the
largest habitat loss took place in the provinces of Santiago del
Estero, Salta, Chaco, and Córdoba, in which over 9 million
ha of forests and shrublands were cleared. However, in rela-
tive terms, the most affected provinces were Tucumán and
Santa Fe, since both have lost over 70% of the original habitat
of this subspecies. The process, however, basically followed a
centripetal pattern, which enhances the likelihood that large
fragments of habitat will persist (Table 2). These provide for a
continuous landscape in 90% of the remaining territory in the
form of a large column of suitable habitat from the northern
limit of the snake’s distribution in the province of Formosa,
to its southernmost limit in the province of San Luis — with
the notable exception of the provinces of Tucumán and Santa
Fe, where the isolation of populations now appears to be irre-
versible (Fig. 5).
Suitable habitat for the Argentina Boa Constrictor in the
18 national and provincial protected areas identified within
its range covers barely 1.7% of its distribution area (716,824
ha), with the aggravating factor that most of these areas
have little to no effective protection. However, the recent
enactment of a National Law for the Protection of Native
Forest (Law 26.331) has promoted the development of Land
Management Plans (LMP) in most provinces of the species’
range. These LMPs establish the areas that should be pre-
served with their original forest cover and those that may be
converted for agricultural use. In a scenario of full compliance
with the LMPs prepared by nine of 13 provinces through
Table 2. Degree of fragmentation of the habitat of Boa constrictor occiden-
talis in Argentina.
Habitat Patch Number Total Area of Average Size
Size (Ha) of Patches Patches (ha) of Patches (ha)
>1,000,000 3 28,205,639 9,401,880
100,000–999,999 1 102,819 102,819
10,000–99,999 25 544,540 21,782
1,000–9,999 281 691,254 2,460
100–999 1,950 550,416 282
>5–100 11,169 235,703 21
Total 13,429 30,330,371
Table 1. Original habitat size and extent of habitat loss for Boa constrictor occidentalis
in Argentina.
Original Current Habitat Habitat
Province Habitat (ha) Habitat (ha) Loss (ha) Loss (%)
Santiago del Estero 11,885,047 7,604,468 4,280,579 35.4
Salta 6,921,872 5,045,602 1,876,270 15.5
Chaco 6,206,342 4,419,698 1,786,644 14.8
Formosa 3,956,459 3,651,826 304,633 2.5
La Rioja 3,987,672 3,607,618 380,054 3.1
Córdoba 3,229,838 1,945,404 1,284,434 10.6
San Luis 2,284,646 1,923,426 361,220 3.0
Catamarca 1,369,510 981,754 387,757 3.2
Tucumán 1,039,506 287,853 751,653 6.2
Santa Fe 693,781 174,375 519,407 4.3
Jujuy 404,975 265,637 139,337 1.2
San Juan 318,897 309,369 9,528 0.1
Mendoza Occasional Occasional
Extent of occurrence 42,298,545 30,217,030 12,081,516 28.6
Fig. 5. Boa constrictor occidentalis habitat loss in Argentina (black areas).
One-third of what is known as the Dry Chaco forests and shrublands has
been converted to crops or to grasslands for livestock production.
8
WALLER ET AL. IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
2010, habitat loss could potentially increase from the current
value of 29% of the species’ original range in Argentina to a
maximum of 46%, which implies that somewhere between
23 to 25 million ha of the original habitat of B. c. occidentalis
would ultimately remain.
Abundance
No scientifically sound references address current or histori-
cal population densities for the Argentine Boa Constrictor.
However, B. c. occidentalis was described as “very abundant”
in the Province of Santiago del Estero during the 1960s
(Abalos et al. 1965), and tens of thousands of skins were
exported every year for five decades for the leather indus-
try before the trade was banned by CITES in 1987 (Godoy
1963, Gruss and Waller 1988). More recently, some authors
(e.g., Kacoliris et al. 2006, Chébez et al. 2008, Waller et al.
2010) have referred to this boa as a common snake in several
parts of its range.
Evaluating abundance in such an extensive range was not
in the scope of our study; however, during inquires made to
rural inhabitants, we found that the species was repeatedly
reported as present throughout most of its distribution area
and even in patchy or marginal habitats (i.e., desert-like areas
of Mendoza, San Luis, and San Juan provinces and forest rel-
icts in the eastern regions of Córdoba, Santiago del Estero,
Tucumán, and Santa Fe provinces). Moreover, during short
surveys in the Province of Formosa, we found these boas can
be locally abundant. In Guadalcazar, for instance, we obtained
about 30 adult-sized specimens in a short period on two dif-
ferent occasions (2003 and 2007). All were captured by local
inhabitants in the immediate surroundings of this small vil-
lage, when crossing dirty roads, or when basking near the dens
of a large rodent, the Plains Viscacha (Lagostomus maximus,
Chinchillidae), located alongside an abandoned airstrip.
National and International Conservation Measures
Aside from the ban on commercial international trade
imposed by the CITES Appendix I listing, no specific con-
servation actions have been undertaken for this species in
Argentina — with the exception of a prohibition on hunt-
ing and trade, both at the national and provincial levels.
Furthermore, the Argentine Boa Constrictor has not yet been
assessed for the Red List by the IUCN, but it is locally con-
sidered Threatened under a different categorization scheme by
Lavilla et al. (2000).
After a 24-year commercial trade ban as a result of the
CITES Appendix I listing, we assessed whether the Argentine
Boa Constrictor meets the criteria for such a listing, or if a
down-listing to Appendix II would be more appropriate.
Annex 4 (Precautionary measures) of resolution Res. Conf.
9.24 (Rev.CoP15) established that “… Species included in
Appendix I should only be transferred to Appendix II if they do not
satisfy the relevant criteria in Annex 1…” and additionally meet
a series of precautionary safeguards (Paragraph A.2.). We have
analyzed each of the biological criteria established in Annex 1
Large-scale deforestation accounts for the loss of one-third of total Boa
Constrictor habitat in Argentina (above); however, these snakes are able to
persist in cultural landscapes providing a matrix of forest remnants among
crops (below). Photographs by Tomás Waller.
Boa constrictor occidentalis occurs almost exclusively in dry forests and
shrublands in what is known as the Chaco region in Argentina, Paraguay,
and presumably Bolivia. Photograph by Tomás Waller.
IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012
9
WALLER ET AL.
of Res. Conf. 9.24 (Rev.CoP15) as they apply to B. c. occiden-
talis and have reached the following conclusions:
Criterion A: The condition that the population is small
is not met. On the one hand, the magnitude of the historical
trade of tens of thousands of skins per year, sustained for over
five decades, can be interpreted as an indication of the resil-
ience and natural abundance of populations. The size of its
current area of distribution in Argentina alone (> 30 million
ha), its capacity to occupy most of the various Chaco habi-
tats, and its persistence even in ecosystems with a long history
of degradation, attest to the existence of a large population
throughout its present range.
Criterion B: The condition that the area of distribution
is restricted is not met. Its range is still mostly continuous
along the Argentinean Dry Chaco (> 30 million ha), reach-
ing also Paraguay (and presumably Bolivia), and the area of
distribution probably exceeds a total of 45 million ha in the
three countries.
Criterion C: Criterion C. Sub-paragraph ii is met, since
it is possible to infer or predict a marked decline in population
size in nature, for the following two reasons: (a) A decrease
in habitat area close to 30%, at least in Argentina (this sur-
vey), and (b) A decrease in habitat quality (and habitat capac-
ity) affecting populations in some areas of its distribution
(Cardozo and Chiaraviglio 2008).
The marked decline described in Criterion C relates pri-
marily to the recent rate of habitat loss, which undoubtedly
led to a gradual reduction of the area of occupancy and, con-
sequently, of population size. Yet these factors do not pose
a threat of extinction at the regional or even national level,
although we envisage future local threat situations in prov-
inces like Santa Fe and Tucumán or in the northeastern sector
of Cordoba, for example, where populations are confined to
isolated forest patches. Considering the past commercial value
of the skin of this subspecies in the international market, an
Appendix I listing is justified on a precautionary basis under
this situation and the uncertainty about the future of the sub-
species’ habitat.
Final Remarks
According to our data, the situation for the Argentine Boa
Constrictor in some provinces may warrant actions at that
level, but on a broad scale, B. c. occidentalis is not endangered
and does not meet the basic conditions for an Action Plan at
the national level. Its distribution only in Argentina is still
very extensive (>30 million ha) and its situation in relation to
land-change patterns does not differ from most species inhab-
iting the Dry Chaco region. Although no evidence points to
an imminent extinction risk or significant trade on a regional
or global scale, the skins’ historical value and the recent
negative habitat trends for B. c. occidentalis justify its current
CITES Appendix I listing under a precautionary approach.
As a consequence of the enactment (2007) and ruling
(2009) of the National Law for the Protection of Native
Forests (Law 26.331), a change in current trends of habi-
tat loss is expected. Consequently, we recommended to the
CITES Secretariat that the listing of B. c. occidentalis in
Appendix I be reviewed again in ten years, taking special
account of the advance of deforestation in Argentina and in
other countries in the range of this taxon.
Although not feasible in the current situation, the possi-
bility of resuming utilization of this subspecies for the benefit
of local communities, under proper management programs,
and in those provinces that properly conserve their native
forests, should not be discarded. Sustainable use of natural
resources present in these ecosystems is one of the few incen-
tives for local communities to conserve them; by depriving
them of this option, their opportunities for development are
limited and their livelihoods threatened. On the other hand,
lack of development opportunities based on utilization of
native resources promotes the gradual replacement of natural
ecosystems by artificial alternatives, particularly those involv-
ing agriculture.
The present situation for the Argentine Boa Constrictor
in the provinces of Tucumán, Santa Fe, and eastern Córdoba,
where the extent of habitat loss and consequent isolation of
populations pose an almost irreversible threat in terms of
their viability, is of particular concern. Specific actions should
be taken to preserve these populations, possibly using the
Argentine Boa as a flagship species to promote the creation of
protected areas.
Recent field research has been concentrated in a few local-
ities in Argentina. Considering the wide range of habitats that
this subspecies occupies and differences observed in life his-
tory traits among, for instance, Córdoba, Santiago del Estero,
and Formosa (Waller et al. 2010; Cardozo and Chiaraviglio
2008, 2011), more studies are needed to ensure that interpre-
tations concerning the conservation status of these popula-
tions are based on adequate sample sizes and representative
observations on appropriate spatial and temporal scales.
Finally, we stress that the best conservation strategy for
this snake is to ensure the maintenance of large tracts of forest
habitat. In this sense, the conservation of the Argentine Boa
Constrictor depends strongly on successful implementation
of the various land management plans recently approved in
the provinces within its range. These hopefully will ensure
habitat conservation for the long term.
Acknowledgements
This work was made possible by support from the CITES
Authorities of Belgium and the CITES Secretariat. We are
particularly indebted to Georges Evrard, Victoria Lichtschein,
and Obdulio Menghi for promoting this project in its early
stages. Guillermo Puccio, Ernesto Alvarenga, Jorge Contreras,
IRCF REPTILES & AMPHIBIANS • 19(1):1–10 • MARCH 2012WALLER ET AL.
10
Federico Rivas, Romina Díaz, Augusto Cuba, Flavio
Moschione, Miguel González, and Bettina Aued collaborated
during various stages of the project.
Literature Cited
Abalos, J.W., E.C. Báez, and R. Nader. 1965. Serpientes de Santiago del Estero.
Acta Zoologica Lilloana 20:211–283.
Astort, E. 1984. La Boa de las Vizcacheras. Fauna Argentina Nº 35. Centro Editor
de América Latina (CEAL), Buenos Aires.
Berst, A. 1944. Las Boas en la Provincia de Santa Fe. Publicación del Museo de
Ciencias Naturales del Colegio de la Inmaculada Concepción de Santa Fe,
Argentina.
Berst, A. 1947. Ofidios útiles. Diario El Orden, 19 de octubre. Santa Fe, Argentina.
Binder, S. and A. Lamp. 2007. Boa constrictor. Die Abgottschlange. Natur und Tier
Verlag, Münster, Germany.
Bolkovic, M.L. 1999. Usos de fauna silvestre de pobladores de las cercanías de la
Reserva Provincial Copo, Santiago del Estero, Argentina, pp. 117–174. In:
T.G. Fang, O.L. Montenegro, and R.E. Bodmer (eds.), Manejo y Conservación
de Fauna Silvestre en América Latina. Museo Noel K. Mercado, Universidad
Autónoma G.R. Moreno, University of Florida, Instituto de Ecología y Wildlife
Conservation Society. Editorial Instituto de Ecología. La Paz, Bolivia.
Bonny, K. 2007. Die Gattung Boa. Taxonomie und Fortpflanzung. Kirschner &
Seufer Verlag, Rheinstetten, Germany.
Burkart, R., N.O. Bárbaro, R.O. Sánchez, and D.A. Gómez. 1999. Eco-regiones de
la Argentina. Administración de Parques Nacionales, Buenos Aires.
Cardozo, G. and M. Chiaraviglio. 2008. Landscape changes influence the reproduc-
tive behaviour of a key ‘capital breeder’ snake (Boa constrictor occidentalis) in
the Gran Chaco region, Argentina. Biological Conservation 141:3050–3058.
Cardozo, G. and M. Chiaraviglio. 2011. Phenotypic plasticity of life history traits in
relation to reproductive strategies in Boa constrictor occidentalis. Evolutionary
Ecology 25:1163–1177.
Cardozo, G., P.C. Rivera, M. Lamfri, M. Scavuzzo, C. Gardenal, and M.
Chiaraviglio. 2007. Effects of habitat loss on the genetic structure of pop-
ulations of the Argentine Boa Constrictor (Boa constrictor occidentalis), pp.
329–338. In: R.W. Henderson and R. Powell (eds.), Biology of the Boas and
Pythons. Eagle Mountain Publishing LC, Eagle Mountain, Utah.
Chébez, J.C., T. Waller, and P.A. Micucci. 2008. Ampalagua, pp. 281–287. In:
J.C. Chébez (ed.), Los Que Se Van. Fauna Argentina Amenazada. Tomo 1.
Editorial Albatros, Buenos Aires.
Daniells, E.A., J.W. Ackley, R.E. Carter, P.J. Muelleman, S.M. Rudman, P.A. Turk,
N.J.lez Espinet, L.A. White, and N.N. Wyszynski. 2008. An annotated check-
list of the amphibians and reptiles of Dominica, West Indies. Iguana 15:130–141.
Di Cola, V., G. Cardozo, M. Lanfri, M. Scavuzzo, and M. Chiaraviglio. 2008.
Modeling the distribution of the boid snakes, Epicrates cenchria alvarezi and
Boa constrictor occidentalis in the Gran Chaco (South America). Amphibia-
Reptilia 29:299–310.
Freiberg, M.A. 1954. Vida de batracios y reptiles sudamericanos. Cesarini Hnos.,
Buenos Aires.
Freiberg, M.A. 1980. La boa de las vizcacheras. Diario La Prensa, 20 de abril.
Buenos Aires.
Godoy, J.C. 1963. Fauna silvestre. Consejo Federal de Inversiones. Evaluación de
los recursos naturales de la Argentina. Volumes 1 and 2. Consejo Federal de
Inversiones (CFI), Buenos Aires.
Gruss, J.X. and T. Waller. 1986. Resumen del problema de la conservación de la
herpetofauna argentina. Amphibia & Reptilia 1:3–13.
Gruss, J.X. and T. Waller. 1988. Diagnóstico y recomendaciones sobre la admin-
istración de recursos silvestres en Argentina: La década reciente (un análi-
sis sobre la administración de la fauna terrestre). CITES-WWF-TRAFFIC
Sudamérica, Buenos Aires.
Henderson, R.W. and R. Powell. 2009. Natural History of West Indian Reptiles and
Amphibians. University of Florida Press, Gainesville.
Henderson, R.W., T. Waller, P. Micucci, G. Puorto, and R. Bourgeois. 1995.
Ecological correlates and patterns in the distribution of Neotropical boines
(Serpentes: Boidae): A preliminary assessment. Herpetological Natural History
3(1):15–27.
Hynková, I., Z. Starostová, and D. Frynta. 2009. Mitochondrial DNA variation
reveals recent evolution of main Boa constrictor clades. Zoological Science
26:623–631.
Kacoliris, F.P., I. Berkunsky, and J. Williams. 2006. Herpetofauna of the
Argentinean impenetrable Great Chaco. Phyllomedusa 5:149–157.
Langhammer, J.K. 1983. A new subspecies of Boa Constrictor, Boa constric-
tor melanogaster, from Ecuador (Serpentes: Boidae). Tropical Fish Hobbyist
32(4):70–79.
Llanos, A.C. and J.A. Crespo. 1952. Ecología de la Vizcacha (Lagostomus maximus
maximus Blainv.) en el nordeste de la provincia de Entre Ríos. Ministerio de
Agricultura y Ganadería, Revista de Investigaciones Agrícolas 6:289–378.
Peters, J.A. and B.R. Orejas-Miranda. 1986. Catalogue of Neotropical Squamata. Part
I. Snakes. Revised edition. Smithsonian Institution Press, Washington, D.C.
Price, R.M. and P.Russo. 1991. Revisionary comments on the genus Boa with
the description of a new subspecies of Boa constrictor from Peru. The Snake
23:29–35.
Philippi, R.A. 1873. Über die Boa der westlichen Provinzen der Argentinischen
Republik. Zeitschrift für die Gesammten Naturwissenschaften 41:127-130.
Rivera, P.C., M. Chiaraviglio, G. Pérez, and C.N. Gardenal. 2005. Protein
polymorphism in populations of Boa constrictor occidentalis (Boidae) from
Córdoba Province, Argentina. Amphibia-Reptilia 26:175–181.
Rivera, P.C., C. Gardenal, and M. Chiaraviglio. 2006. Sex biased dispersal and high
levels of gene flow among local populations in the Argentine Boa Constrictor,
Boa constrictor occidentalis. Austral Ecology 31:948–955.
The Nature Conservancy (TNC), Fundación Vida Silvestre Argentina (FVSA),
Fundación para el Desarrollo Sustentable del Chaco (DeSdelChaco) and
Wildlife Conservation Society Bolivia (WCS). 2005. Evaluación Ecorregional
del Gran Chaco Americano. Fundación Vida Silvestre Argentina, Buenos Aires.
Unión Internacional para la Conservación de la Naturaleza (UICN). 2001.
Categorías y criterios de la Lista Roja de la UICN. Versión 3.1. Preparado por la
Comisión de Supervivencia de Especies de la UICN. Unión Mundial para la
Naturaleza. Gland, Switzerland.
Waller, T. 1987a. Boa de las vizcacheras: Más que una necesidad, una deuda con
la especie. FVSA/RIE/AOP-NotiCITES’87 1(1): 1. Boletín preparado para su
distribución durante la VI Reunión de la Conferencia de las Partes en CITES,
Ottawa, Canadá.
Waller, T. 1987b. Propuesta de Inclusión de Boa constrictor occidentalis en el
Apéndice I de la Convención sobre el Comercio Internacional de Especies
Amenazadas de la Fauna y Flora Silvestres (CITES). Documento presentado
por la República Oriental del Uruguay en la VI Reunión de la Conferencia de
las Partes en CITES, Julio de 1987, Ottawa, Canadá.
Waller, T. 1992. De nuestro libro rojo. Ficha 26: Boa de las Vizcacheras.
Fundación Vida Silvestre Argentina, Revista Vida Silvestre 27:25–26.
Waller, T. and P.A. Micucci. 1993. Estado actual del conocimiento de la biología,
comercio y conservación de las boas neotropicales: Géneros Boa L. (1758) y
Eunectes Wagler (1830) (Reptilia: Serpentes: Boidae). TRAFFIC Sudamérica y
la Secretaría CITES, Buenos Aires.
Waller, T., P.A. Micucci, and E.B. Palumbo. 1995. Distribución y conservación de la
familia Boidae en el Paraguay. Autoridad Científica CITES, Secretaría CITES
y TRAFFIC Sudamérica, Asunción, Paraguay.
Waller, T., P.A. Micucci, M. Barros, J. Draque, and C. Estavillo. 2010.
Conservación de la Boa Ampalagua (Boa constrictor occidentalis) en la
República Argentina A 20 años de su inclusión en el Apéndice I de la
CITES. Proyecto CITES No. S-298. Fundación Biodiversidad–Argentina,
Buenos Aires.
... tine Boa (Boa constrictor occidentalis), the two largest species, which share the same range and habitat. Waller et al. (2012) report a 29% decrease in the historical range of B. c. occidentalis in Argentina resulting from clearing and replacement of forests and scrubland with crops and livestock pastures. These findings can be assumed to also hold true for Salvator rufescens in Argentina, because both crops and pasture land are typically devoid of any original vegetation. ...
Article
Full-text available
The goal of this work is to determine and to evaluate threats to Salvator rufescens. The life history of S. rufescens shows a close association with forest habitats, therefore habitat loss and alteration are the main direct threats identified for the species. Indirect consequences of habitat loss are lower reproduction success, higher predation rates and the loss of individuals through road kill. These are therefore additional negative factors within and in the areas surrounding remaining adequate habitat patches. Our findings can serve as a case study showing that, in arid habitats , even formerly abundant species like S. rufescens may be threatened by rapid habitat loss and alteration. In particular the permanent availability of water introduced by livestock farming causes a shift in the composition of native species and may result in a higher predation rate and/or nutrition competition with negative consequences for various autochthonous species.
Article
Full-text available
Wildlife surveys are essential to conserve the biodiversity of a given region or area. In addition, in the light of ecosystem conservation problems, these surveys allow us to quickly identify which species should be a priority for conservation policies. Almost two decades have gone by since the last commented list of the snakes of Argentina was published, a period in which numerous and significant taxonomic changes have been made at a generic and specific level, and new species have been described, in addition to the inclusion of others previously recorded only in neighboring countries. This work is intended to update the systematic status of Argentine snakes and assemble information on their feeding habits, conservation, reproduction, etymology, common names, taxonomic changes, and main symptoms reported in accidents involving several colubrids and medically important viperid snakes. For this purpose, we carried out an extensive bibliographic review about Argentina and neighbouring countries snakes. In addition, we reviewed digital databases, and included our own unpublished data from herpetological collections and field work. To determine conservation status, we used the most recent categorization of Argentine snakes and the IUCN digital database. We present novel data for 8 families and 129 snake species that inhabit the Argentine territory.
Article
Full-text available
The following document is the final report of CITES Project "Distribution and Utilization of the family Boidae in Paraguay". Survey work has been carried out between June 1st, 1994 and March 1st, 1995 under contract among the CITES Secretariat, the Scientific Authority of Paraguay and TRAFFIC South America, with the financial support of the European Union (EU)
Article
Many wild reptile species are threatened by habitat loss. However, the way in which changes in landscape patterns influence intraspecific ecological processes is not completely understood. Boa constrictor occidentalis is an endangered species and has a special conservation value since it is endemic of dry forests in the Gran Chaco region. Because the Gran Chaco is largely threatened due to habitat loss it is necessary to know how landscape changes influence this species. Therefore, we evaluated the effects of forest loss and landscape composition on the reproductive life-history parameters. Landscape changes were assessed by analyzing satellite imagery and reproductive parameters were determined by ultrasound images of the reproductive structures. The obtained results indicate that habitat loss may affect body condition, clutch size and testicular volume of the Argentine boa constrictor. We also found that the spatial pattern of vegetation influences the distribution of females and males in the landscape. Matting aggregations are scarce in shrublands. Therefore, our study shows that forest loss could enhance vulnerability to extirpation through constraints placed on reproduction. We encourage resource managers to evaluate sensitive reproductive life-history parameters as well as habitat deterioration to asses the conservation status of the populations of the Argentine boa constrictor. Since the Gran Chaco forest, a key habitat to the species’ reproduction, is largely threatened, strong conservation action is needed to halt and reverse forest loss in this region.