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Hunting practices and harvest of peccaries in the northern Paraguayan Dry Chaco
Abstract
Overexploitation is a frequently cited driver of species extinction. Throughout the Neotropics, balancing traditional practices and the needs of local people with protection of rare or declining species is challenging, especially given low capacity for control by authorities. We conducted interviews with wildlife professionals and residents, along with a camera-based field survey of wildlife occurrence, to gain insight into recent population trends, relative abundance, and drivers of harvest for large mammals in the northern Dry Chaco of Paraguay including but not limited to, Defensores del Chaco National Park. Although the endangered Chacoan peccary (Catagonus wagneri) was preferred regardless of hunter motivation, harvests of all species appeared largely opportunistic, and limited to immediate family use due to a lack of market forces, and constraints on refrigeration capacity in the region. This pattern may soon change given rapid deforestation, and an associated and growing road network providing greater access both to wildlife resources and commercial bushmeat markets. Notably, public perception of abundance and trends for Chacoan peccary differed from professional opinions—likely due in part to greater use of areas along roads by C. wagneri compared to other, relatively more abundant species. This discordance may pose future challenges if harvest restrictions become a conservation necessity, especially during a process of essentially self-imposed voluntary limitations.
... Dicotyles tajacu, Semper-Pascual et al. 2019). Furthermore, protected areas seem insufficient to conserve large mammals as these have poor representation of terrestrial vertebrates (Nori et al. 2016), are disconnected from each other (De la Sancha et al. 2021;Matteucci and Camino 2012), and hunting and deforestation may occur within their boundaries (De la Sancha et al. 2021, Saldivar-Bellassai et al. 2021). The Dry Chaco may be undergoing a defaunation process whereby most wildlife species are rapidly disappearing, and we do not know how long diversity can last (Periago et al. 2015;Romero-Muñoz et al. 2020). ...
... For most species in the Dry Chaco, information and conservation attention is scarce Periago et al. 2015;Nori et al. 2016;Saldivar-Bellassai et al. 2021). Such is the case of the chacoan peccary (Catagonus wagneri), that is endemic to the Dry Chaco (over 90% of its habitat occurs in the region; Altrichter et al. 2016;Ferraz et al. 2016). ...
... The chacoan peccary (ChP hereafter) is a habitat specialist that only occupies areas with high forest-cover (Altrichter and Boaglio 2004;Ferraz et al. 2016;Taber et al. 1993;Torres et al. 2018), and it has not been detected in landscapes dominated by industrial agriculture (Ferraz et al. 2016;Núñez-Regueiro et al. 2015). Habitat loss is, therefore, the main threat to the species (Altrichter et al. 2015Camino and Torres 2019) and its populations are also negatively affected by high hunting pressure (Altrichter 2005;Camino et al. 2018;Romero-Muñoz et al. 2020;Saldivar-Bellassai et al. 2021). There are other threats to the species, for example competition with introduced species, such as feral pigs (Sus scrofa), diseases, or attacks by dogs, among others (Camino and Torres 2019). ...
The Dry Chaco has one of the highest deforestation rates of the world. The chacoan peccary (Catagonus wagneri; ChP) is endemic to the forests of this region and faces a high risk of extinction. However, we lack sufficient information about this species to develop effective conservation actions. This is the first study to determine the relevance of primary and secondary forest as habitat for the species and to address opportunities for conservation. We used occupancy modelling to study habitat selection. Using additional information on the species and the region, we then estimated the time left before the ChP’s habitat outside of protected areas is completely lost, and the number of ChP generations likely to exist before this happens. Finally, we identified protected areas that can sustain viable populations, and estimated the number of individuals that can survive within them. We found that the ChP occupies both primary forests and secondary forests. Also, that if deforestation rates remain consistent, the habitat for the ChP outside protected areas will have disappeared before 2051 (< 6 peccary generations). Furthermore, we found that most protected areas are too small and isolated to sustain viable populations. Our results have great management implications. Well-managed forests may allow the conservation of the ChP. Initiatives focused on forest conservation should increase, alongside the restoration of degraded and deforested areas. We also recommend the creation of new protected areas and wildlife corridors, and working horizontally with local communities.
... Members of the Tayassuidae family, including white-lipped peccaries (Pecari tajacu) and collared peccaries (Tayassu pecari), have a wide geographic distribution in South America and are found in all Brazilian biomes. These animals are a source of meat obtained mainly through hunting for populations in tropical countries [1,2]. Wild populations of these animals have declined because of overhunting and a reduction in their natural biomes [2]. ...
... These animals are a source of meat obtained mainly through hunting for populations in tropical countries [1,2]. Wild populations of these animals have declined because of overhunting and a reduction in their natural biomes [2]. Faced with a reduction in these free-living populations, commercial farms of familiar producers and Amazonians have emerged. ...
Salmonella spp. and Escherichia coli are implicated in human and animal infections and require antimicrobial treatment in many situations. Faecal samples of healthy white-lipped peccaries (Pecari tajacu) (n = 30) and collared peccaries (Tayassu pecari ) (n = 60) obtained in three farms located in the Midwest Brazil. The antimicrobial profiles of commensal E. coli from P. tajacu and T. pecari from commercial herds in Brazil were isolated and analyzed and virulence genes were detected. Among 90 healthy animals, no Salmonella spp. were isolated. However, 30 samples (27%) tested positive for E. coli, with 18 isolates from P. tajacu and 12 from T. pecari, representing frequencies of 58.0% and 38.7%, respectively. Additionally, other Enterobacteriaceae family bacteria were detected but not included in this analysis. However, individual samples from 30 animals tested positive for E. coli, of which 16 were isolated from P. tajacu presenting multidrug resistance and six were isolated from T. pecari presenting a similar pattern. The E. coli virulence genes detected were papC (pilus-associated pyelonephritis) in five isolates, tsh (temperature-sensitive hemagglutinin) in one isolate, and eae (enteric attachment and effacement) in one isolate. The serum resistance gene, iss (increased serum survival), was detected in four isolates. An association between these genes and the presence of hemolysin was also observed in one isolate. Thus, T. pecari and P. tajacu are potential reservoirs of pathogenic and multidrug-resistant and E. coli. Faecal E. coli of healthy P. tajacu and T. pecari could act as a possible reservoir of antimicrobial resistance genes in environment.
... More than 20% of all Chacoan woodlands have been replaced by croplands and pastures between 1985 and 2015 (Baumann et al., 2017). Remaining forests are largely inhabited by forest-dependent people that often practice subsistence hunting (Camino et al., 2018;Levers et al., 2021;Saldivar-Bellassai et al., 2021;Tamburini & Cáceres, 2017). ...
... Our study also provides further evidence that hunting pressure interacts with land change in synergistic ways (Gallego-Zamorano et al., 2020). For instance, agricultural expansion typically leads to the construction of roads, which grants hunters access to formerly inaccessible areas, and generally increases the interface between hunters and wildlife (Benítez-López et al., 2017, 2019Saldivar-Bellassai et al., 2021). As we show for the Chacoan peccary, such situations are recurrent in the Chaco, where the habitat for many other mammals has been degraded or lost due to the combined effect of hunting and land conversion (Benítez-López et al., 2019;Romero-Muñoz et al., 2020). ...
Aim
Land‐use change and overexploitation are major threats to biodiversity, and climate change will exert additional pressure in the 21st century. Although there are strong interactions between these threats, our understanding of the synergistic and compensatory effects on threatened species' range geography remains limited. Our aim was to disentangle the impact of habitat loss, hunting and climate change on species, using the example of the endangered Chacoan peccary (Catagonus wagneri).
Location
Gran Chaco ecoregion in South America.
Methods
Using a large occurrence database, we integrated a time‐calibrated species distribution model with a hunting pressure model to reconstruct changes in the distribution of suitable peccary habitat between 1985 and 2015. We then used partitioning analysis to attribute the relative contribution of habitat change to land‐use conversion, climate change and varying hunting pressure.
Results
Our results reveal widespread habitat deterioration, with only 11% of the habitat found in 2015 considered suitable and safe. Hunting pressure was the strongest single threat, yet most habitat deterioration (58%) was due to the combined, rather than individual, effects of the three drivers we assessed. Climate change would have led to a compensatory effect, increasing suitable habitat area, yet this effect was negated by the strongly negative and interacting threats of land‐use change and hunting.
Main Conclusions
Our study reveals the central role of overexploitation, which is often neglected in biogeographic assessments, and suggests that addressing overexploitation has huge potential for increasing species' adaptive capacity in the face of climate and land‐use change. More generally, we highlight the importance of jointly assessing extinction drivers to understand how species might fare in the 21st century. Here, we provide a simple and transferable framework to determine the separate and joint effects of three main drivers of biodiversity loss.
... This has resulted in a conversion of about 25% of the Chaco to agriculture (Baumann et al. 2017). Moreover, hunting is widespread across the Gran Chaco, practiced by a range of actors, including indigenous peoples, smallholder subsistence ranchers, large-scale ranchers, and soybean producers, who hunt wildlife for subsistence, leisure, or retaliatory reasons (Altrichter 2005;Camino et al. 2018;Saldivar-Bellassai et al. 2021). Unsustainable hunting practices likely contribute to declines of multiple species (Periago, Chillo, and Ojeda 2014;Romero-Muñoz, Benítez-López, et al. 2020). ...
Aim
We investigated the effects of habitat destruction and hunting on the functional decline of top predators, specifically jaguar and puma, in the Gran Chaco.
Location
The 1.1 million km² South American Gran Chaco.
Methods
We used spatially explicit, individual‐based models for jaguars and pumas, incorporating detailed information on habitat suitability and hunting pressure. We parameterized our models with literature data and calibrated them through a Delphi expert‐elicitation process. We simulated population trajectories under a hypothetical, threat‐free, baseline versus different threat scenarios.
Results
Under combined threats of hunting and habitat loss, jaguar and puma populations declined by 88% and 80%, respectively, compared to range contractions of 48% and 35%, respectively. Both species remained regionally viable, particularly due to large protected areas, which acted as population sources but were surrounded by strong sinks. We observed a widespread weakening of the top carnivore guild function, with at least one species extirpated across 67% of the Chaco and strong declines (> 80%; considered here as functional loss) for both species concurrently across 61% of their area of historical co‐occurrence. Hunting was a much stronger driver of population declines (88% and 77% for jaguars and pumas, respectively) compared to habitat destruction (26% and 22%).
Main Conclusions
Large predators play key functional roles in ecosystems. Our findings reveal that these functions can be lost over vast areas due to the combined effects of habitat destruction and hunting, with functional loss extending far beyond the areas of species' extirpation. Very large protected areas, like Kaa‐Iya in Bolivia, are crucial for maintaining viable populations of top predators, highlighting the pressing need for increased protection and connectivity in the Chaco to prevent further trophic downgrading. More generally, our research underscores the value of spatially detailed, mechanistic models for disentangling the complex dynamics of multiple threats on ecological functioning at broad scales.
The chapter contributes to both archaeological and ethnozoological research by describing the knowledge system of squirrel species use and the connection between squirrel species and the cultural beliefs of the tribes. The study, carried out from December 2018 to November 2019, aimed to document the utilization of squirrel species for various purposes by the Adi, Idu Mishmi, Miju Mishmi, Tangsa, Chakma, and Monpa tribes living near villages adjacent to protected areas in the districts of East Siang, Lower Dibang Valley, Dibang Valley, Lohit, Changlang, and West Kameng of Arunachal Pradesh, India. The study found that eleven squirrel species are used by these tribes for cultural, food, and medicinal purposes. The chapter details the various tools and techniques used by the tribes to hunt squirrels and their use of certain squirrel species as part of their traditional culture, including their names in English, the vernacular, and Latin.
Habitat destruction and overexploitation are the main threats to biodiversity and where they co‐occur, their combined impact is often larger than their individual one. Yet, detailed knowledge of the spatial footprints of these threats is lacking, including where they overlap and how they change over time. These knowledge gaps are real barriers for effective conservation planning. Here, we develop a novel approach to reconstruct the individual and combined footprints of both threats over time. We combine satellite‐based land‐cover change maps, habitat suitability models and hunting pressure models to demonstrate our approach for the community of larger mammals (48 species > 1 kg) across the 1.1 million km² Gran Chaco region, a global deforestation hotspot covering parts of Argentina, Bolivia and Paraguay. This provides three key insights. First, we find that the footprints of habitat destruction and hunting pressure expanded considerably between 1985 and 2015, across ~40% of the entire Chaco – twice the area affected by deforestation. Second, both threats increasingly acted together within the ranges of larger mammals in the Chaco (17% increase on average, ± 20% SD, cumulative increase of co‐occurring threats across 465 000 km²), suggesting large synergistic effects. Conversely, core areas of high‐quality habitats declined on average by 38%. Third, we identified remaining priority areas for conservation in the northern and central Chaco, many of which are outside the protected area network. We also identify hotspots of high threat impacts in central Paraguay and northern Argentina, providing a spatial template for threat‐specific conservation action. Overall, our findings suggest increasing synergistic effects between habitat destruction and hunting pressure in the Chaco, a situation likely common in many tropical deforestation frontiers. Our work highlights how threats can be traced in space and time to understand their individual and combined impact, even in situations where data are sparse.
El pecarí del Chaco conocido localmente en Para-guay como tagua (Catagonus wagneri) es una es-pecie en peligro de extinción endémica del Chaco Americano, cuya situación se mantiene en dete-rioro como consecuencia de la pérdida y transfor-mación de su hábitat y de la caza excesiva en toda su área de distribución. Este trabajo presenta los resultados obtenidos y la información recopilada durante el taller " Estrategia Regional para la Con-servación del Tagua " realizado en la ciudad de Asunción del Paraguay durante marzo del año 2016. En base a datos biológicos, parámetros poblaciona-les, puntos de presencia de la especie, datos de de-forestación y cacería, describimos la situación de la especie en cada país, modelamos la distribución de la especie y aptitud del hábitat con el programa Maxent y los efectos de la cacería en la viabilidad poblacional con el programa Vortex. La ecoregión Chaqueña posee una de las mayores tasas de de-forestación mundial, debido a la expansión de la ganadería y de la agricultura generando como con-secuencia una pérdida de hábitat que representa la mayor amenaza para la supervivencia de la espe-cie. En Paraguay, la deforestación en el centro del Chaco amenaza las poblaciones remanentes de ta-gua. En Argentina la rápida degradación de la vege-tación nativa y las falencias en la implementación de normativas que manejan el bosque indican que la situación del tagua es precaria. La información disponible para la especie en Bolivia se restringe al Parque Nacional Kaa-Iya, sin embargo, la aptitud del hábitat dentro del parque y en el resto del Chaco boliviano es alta lo cual indicaría que el tagua po-dría estar en mejores condiciones de conservación que en los otros dos países. Los modelos de aptitud del hábitat muestran que la cobertura del suelo, la isotermalidad y la elevación son las variables me-jor correlacionadas con la presencia de la especie. Aproximadamente 46% de la superficie del Gran Chaco sería apta para la especie, y únicamente el 12% del área con la mejor aptitud está incluido en un sistema oficial de protección. Según el modelo de viabilidad poblacional se requieren poblaciones mínimas de entre 1000 y 1300 individuos, en ausen-cia de amenazas de origen humano (ej.: caza), para que la especie sobreviva por lo menos 100 años sin perder variación genética. Con tasas anuales de cacería del 20% y del 10% la especie debería extin-guirse en 20 y 100 años respectivamente. Sin embargo , una cacería que coseche el 5% de la pobla-ción podría ser sustentable, si no hubiera pérdida de hábitat. La dramática conversión de superficies naturales sumada a la reducida superficie de áreas aptas protegidas y a la presión de caza determina que la conservación del tagua a largo plazo se vea amenazada. Es necesario continuar con trabajos de investigación que permitan obtener datos de cali-dad para posibilitar la gestión y manejo sostenible de la especie. Es indispensable que se revisen las políticas de uso del suelo y se implementen contro-les a la deforestación masiva que ponen en peligro el tagua y el resto de la biodiversidad del Chaco.
The Chacoan peccary known locally in Paraguay as tagua (Catagonus wagneri) is an endangered species endemic to the Gran Chaco. Its situation continues to deteriorate as a consequence of habitat loss and transformation, as well as excessive hunting throughout its range. This study presents results and information obtained during the workshop " Regional strategy for the conservation of the tagua " , held in Asunción, Paraguay, in March 2016. Using population parameters as well as biological, species presence, hunting and deforestation data, we describe the conservation status in each country, model the species distribution and habitat suitabil-ity using Maxent software and the effects of hunting on population viability using Vortex software. The Chaco region has one of the highest deforestation rates in the world due to the expansion of agriculture and pastures, leading to habitat loss, which is currently the largest threat to the species survival. In Paraguay, high deforestation in the center of the Chaco threatens the remnant tagua populations. In Argentina, rapid degradation of the native vegetation and deficient implementation of land management legislation indicate a precarious situation for the species. The information about the species in Bolivia is restricted to the Kaa-Iya National Park, however, high habitat suitability in the park and outside indicate that the species may have a better conservation status than in the other countries. Habitat suitability models show that land cover, isothermal-ity and elevation are the variables that best explain the species' presence. Approximately 46% of the Gran Chaco is suitable for the species, but only 12% of the area with high suitability is under some type of protection. According to the population viability model done with the software Vortex, a minimum population of 1000 to 1300 individuals is required, with no human threats, to ensure that the species will survive for 100 years without losing genetic diversity. With annual hunting rates of 20% and 10% of the population, the species would go extinct in 20 and 100 years respectively, however, a harvest rate of 5% could be sustainable in the absence of habitat loss. The dramatic conversion of natural habitat, in addition to the small area that is protected and the persistence of illegal hunting threaten the future of the species. Further research is required to generate the data necessary to manage the conservation and potential use of the species. Land use policies must be revised, and the deforestation and illegal hunting that jeopardize the tagua and the entire Chaco biodiversity must be controlled.
Abstract
The Chacoan peccary (Catagonus wagneri), or Tagua, an endemic species living in the Chaco ecoregion, is endangered by highly increasing deforestation rates across the region, particularly
in the last decade. This situation highlights the need to better understand the current distribution of the species, as well as how environmental conditions affect habitat suitability. This study
predicts the distribution of the Chacoan peccary and evaluates the current environmental conditions in the Chaco for this species. Using six environmental variables and 177 confirmed occurrence records (from 2000 to 2015) provided by researchers, we developed a Species Distribution Model (SDM) applying the Maxent algorithm. The final model was highly accurate and significant (p < 0.001; AUC 0.860 ± 0.0268; omission error 1.82 %; posthoc validation of
omission error using independent presenceonly records 1.33 %), predicting that 46.24 % of the Chacoan Peccary Chaco is suitable habitat for the Chacoan peccary, with the most important areas concentrated in the middle of Paraguay and northern Argentina. Land cover, isothermality and elevation were the variables that better explained the habitat suitability for the Chacoan peccary. Despite some portions of suitable areas occurring inside protected areas, the borders and the central portions of suitable areas have recently suffered from intensive deforestation and development, and most of
the highly suitable areas for the species are not under protection. The results provide fundamental insights for the establishment of priority Chacoan peccary conservation areas within its range.
The Amazon basin is the largest and most species-rich tropical forest and river system in the world, playing a pivotal role in global climate regulation and harboring hundreds of traditional and indigenous cultures. It is a matter of intense debate whether the ecosystem is threatened by hunting practices, whereby an “empty forest” loses critical ecological functions. Strikingly, no previous study has examined Amazonian ecosystem resilience through the per- spective of the massive 20th century international trade in furs and skins. We present the first historical account of the scale and impacts of this trade and show that whereas aquatic species suffered basin-wide population collapse, terrestrial species did not. We link this differential resilience to the persistence of adequate spatial refuges for ter- restrial species, enabling populations to be sustained through source-sink dynamics, contrasting with unremitting hunting pressure on more accessible aquatic habitats. Our findings attest the high vulnerability of aquatic fauna to unregulated hunting, particularly during years of severe drought. We propose that the relative resilience of terres- trial species suggests a marked opportunity for managing, rather than criminalizing, contemporary traditional sub- sistence hunting in Amazonia, through both the engagement of local people in community-based comanagement programs and science-led conservation governance.
The Sustainable Development Reserve (RDS) model in Brazil provides legal context for monitoring wildlife with the involvement of local populations in gathering data and developing strategies for sustainable use. We present results of one year of self monitoring by hunters in five communities within the RDS-PP, discuss how the observed patterns reflect local hunting regulations, and suggest how this information could be incorporated into a formal management system. In addition to the offtake data, we interviewed hunters, inquiring about informal community hunting norms and agreements, and analysed the content of 19 rules in the reserve's management plan. 509 hunting events were recorded by 37 of the 104 families present (35%). Self monitoring permitted the evaluation of temporal and spatial fluctuations of hunting activities, notably regarding ease of canoe transport during the high-water season. Though communities have been apprehensive about developing regulations for subsistence hunting, one of the communities had developed a set of formal rules. Hunting for commercial sale to outsiders and restrictions on external hunters are concerns shared by the local population and the reserve management agencies. Such data and understanding are crucial to the management of protected areas in the Brazilian Amazon, where governance is often limited.
Hunting is one of the principal causes of wildlife declines throughout the tropics. Even with an increase in the number of reserves, protecting wildlife has proven difficult and many reserves remain little different from unprotected areas. In Brazil, private landowners are being encouraged by federal and state governments and non-governmental organizations to participate in a national conservation strategy by setting aside land for preservation. However, due to chronic hunting pressure, the role that private reserves might play remains to be determined. In this study we analyze the potential of private reserves through a case study of the Reserva Ecológica Michelin in Bahia, Brazil. We measured the relative abundances of medium and large mammals before and after the implementation of guard patrols, to determine the efficacy of this management strategy for protecting wildlife. The relative abundance of the fauna increased by 72.6 % after the initiation of guard patrols, from 5.07 to 8.68 encounters/10 km, with preferred game species (Dasypus novemcinctus, Cuniculus paca, Pecari tajacu, and Mazama americana) increasing by 146.7-300%. Similarities between the relative abundances of preferred game species at our site after the initiation of the guard patrols and those of other protected Neotropical reserves indicate that the Michelin reserve is now being effectively protected. Although the cost of $9.4/ha to protect the reserve is high, this study shows that the private reserve initiative can be an effective component of the national conservation strategy.
Land-use and land-cover change has been a topic that has called the attention of the scientific community for decades. Because of the importance of tropical and subtropical forest ecosystems, investigations into the causes and processes (e.g., underlying and proximate causation) that drive land use and land-cover change have typically concentrated on these regions. Consequently, little work has been done to understand the proximate and underlying drivers of land use and land-cover change in one of the least disturbed forests worldwide, the Paraguayan dry Chaco in South America. This article attempts to fill this gap in the literature by focusing on the processes and drivers behind land-cover change in the Paraguayan Chaco. More specifically, this article links underlying and proximate causes to regional land-cover change. To accomplish this task the study makes use of Moderate Resolution Imaging Spectroradiometer (MODIS) data and census data. Results show major land-cover changes. Different from other dry regions in South America where soybean expansion has been pointed out as main driver of land-cover change, in the Paraguayan Chaco, cattle ranching is a major driver of forest loss.
We report a range-wide status assessment of a key Neotropical ecosystem architect, the white-lipped peccary Tayassu pecari, categorized as Near Threatened on the IUCN Red List, using published information and unpublished data from 41 scientists in 15 range countries. We estimate that the white-lipped peccary has been extirpated in 21% of its historical range over the last 100 years, with reduced abundance and a low to medium probability of long-term survival in another 48% of its current range. We found major range declines in Argentina, Paraguay, southern Brazil, Colombia, Venezuela, north-east Brazil, Mexico and Costa Rica. This species is particularly at risk in more xeric ecosystems, especially the caatinga, cerrado and pampas. Hunting and habitat destruction are the most severe threats, although there are also unexplained sudden die-offs suggestive of disease. We evaluate our results in light of this species’ important interspecific interactions and its role as an ecosystem architect. One of our recommendations is that conservation efforts should focus on landscape conservation of large, continuous and ecologically intact areas containing a mosaic of different habitat types.
Hunting is an important component of native subsistence strategies in Amazonia. It is also a serious threat to biodiversity in some areas. We present data on the faunal harvests of two native Neotropical subsistence hunting peoples, Machiguenga bow-hunters and Piro shotgun hunters of Peru. The rate of annual harvest per square kilometer of catchment is estimated and compared to rates of sustainable harvest calculated by Robinson and Redford (1991). We used indicators of prey abundance to test for the depletion of species that hunters killed in numbers greater than what the model predicts to be sustainable. As predicted, we found the strongest evidence for local depletion of the large primates at the Piro site. The woolly monkey ( Lagothrix lagothricha) harvest at the Machiguenga village and the deer ( Mazama americana) and collared peccary (Tayassu tajacu) harvests at both sites were not predicted to be unsustainable and we found no evidence for depletion. Machiguenga bow hunters killed spider monkeys (Ateles paniscus) in quantities that were slightly above what the model predicted to be sustainable, yet we found no evidence for depletion. Differential species vulnerability, catchment size, and consumer population size could be important factors in determining sustainability.
Subsistence hunting practiced by poor rural and indigenous people in Latin America differentially affects the three species of peccaries (Artiodactyla: Tayassuidae). Sustainability of subsistence hunting of peccaries in the Argentine semi-arid Chaco, where the three species coexist, was unknown. My objectives were to determine the importance of peccaries for the local people, describe the current pattern of hunting and its impact on the three species of peccary and identify the factors that affect hunting sustainability. I found that many rural (70%) and village people (40%) consumed peccaries. White-lipped and chacoan peccaries were more susceptible to overharvesting than collared peccary. Current rates of hunting of white-lipped and chacoan peccaries are likely not sustainable because: (a) density of both species was between two to three times higher inside a protected area than outside; (b) populations have declined near larger villages and in older settlements; (c) herds sizes were small in comparison with other regions; (d) large number of juveniles less than one year old were harvested; (e) hunting did not discriminate based on sex or reproductive status and (f) The unified harvest model indicated unsustainable harvest because more than 40% of the reproductive production was taken and populations densities were less than 60% carrying capacities. In contrast, harvest of collared peccary seems sustainable at the current rates of hunting by rural peasants. Other threats such as forest exploitation, however, are accelerating, and are likely to reduce sustainability.
Jaguar and puma depredation on livestock may be influenced by (1) innate and learned behavior; (2) health and status of individual cats; (3) division of space and resources among jaguar and puma; (4) cattle husbandry practices; and (5) abundance and distribution of natural prey. Our study in Los Llanos of Venezuela aimed to establish how all these elements related to cattle being lost to cat depredation. Prey distribution was influenced by forest composition, topographical characteristics, and degree of habitat interspersion. The biomass of natural prey in the study area was adequate to support the resident large cats without a subsidy of livestock. Selective rather than opportunistic hunting by the cats reinforced that conclusion. Puma were responsible for more attacks on livestock than jaguar, frequently in maternity pastures in upland areas of relatively low prey availability. Management recommendations are discussed that may be relevant to other savanna/forest mosaics of South America.
Protein from forest wildlife is crucial to rural food security and livelihoods across the tropics. The harvest of animals such as tapir, duikers, deer, pigs, peccaries, primates and larger rodents, birds and reptiles provides benefits to local people worth millions of US$ annually and represents around 6 million tonnes of animals extracted yearly. Vulnerability to hunting varies, with some species sustaining populations in heavily hunted secondary habitats, while others require intact forests with minimal harvesting to maintain healthy populations. Some species or groups have been characterized as ecosystem engineers and ecological keystone species. They affect plant distribution and structure ecosystems, through seed dispersal and predation, grazing, browsing, rooting and other mechanisms. Global attention has been drawn to their loss through debates regarding bushmeat, the “empty forest” syndrome and their ecological importance. However, information on the harvest remains fragmentary, along with understanding of ecological, socioeconomic and cultural dimensions. Here we assess the consequences, both for ecosystems and local livelihoods, of the loss of these species in the Amazon and Congo basins.
The concept of ecosystem engineering has catalysed novel approaches and models for non-trophic species interactions and ecosystem functions. Ecosystem engineers physically modify abiotic and biotic environments, thereby creating new habitats that can be colonized by a new suite of species. In the Peruvian Amazonas, we tested whether peccaries (Tayassuidae) function as ecosystem engineers by creating and maintaining wallows. Such wallows could be critical aquatic habitats and breeding sites for anuran species during dry seasons. We compared hydroperiods of 21 peccary wallows and 13 naturally formed ponds across three dry seasons and found that wallows had a consistently higher mean water surface area than ponds. We also examined the pH, dissolved oxygen and temperature, and found no significant differences in these parameters between water bodies. Wallows had a significantly higher density of tadpoles, metamorphs and adult anurans, as well as higher -diversity and species richness than ponds. This study not only provides the first systematic evidence of the ecosystem engineering processes of peccaries, but also reveals the positive consequences of such for anuran species.
Wild animals are an important source of protein for the rural peoples living in or near tropical forests. However, the resource can easily be overexploited and game species can become locally depleted, or even extinct. This paper discusses attempts to measure the sustainability of hunting in tropical forests. It examines five indices of sustainability in current use and two models that attempt to model sustainability.
Subsistence game bunting has profound negative effects on the species diversity, standing biomass, and size structure of vertebrate assemblages in Amazonian forests that otherwise remain largely undisturbed. These effects are likely to be considerably aggravated by forest fragmentation because fragments are more accessible to hunters, allow no (or very low rates of) recolonization from nonharvested source populations, and may provide a lower-quality resource base for the frugivore-granivore vertebrate fauna. I examined the likelihood of midsized to large-bodied bird and mammal populations persisting in Amazonian forest fragments of variable sizes whenever they continue to be harvested by subsistence hunters in the aftermath of isolation. I used data from a comprehensive compilation of game-harvest studies throughout Neotropical forests to estimate the degree to which different species and populations have been overharvested and then calculated the range of minimum forest areas required to maintain a sustainable harvest. The size distribution of 5564 Amazonian forest fragments-estimated from Landsat images of six regions of southern and eastern Brazilian Amazonia-clearly shows that these are predominantly small and rarely exceed 10 ha, suggesting that persistent overhunting is likely to drive most midsized to large vertebrate populations to local extinction in fragmented forest landscapes. Although experimental studies on this negative synergism remain largely unavailable, the prospect that increasingly fragmented Neotropical forest regions can retain their full assemblages of avian and mammalian species is unlikely.
Over 1,400,000 m of line transect data were collected in collaboration with Ache Indians to determine encounter rates with all large vertebrates in the Mbaracayu Reserve Paraguay. The data were analyzed using logistic regression in order to determine the impact of human hunting on animal encounter rates in the reserve. The method controlled for effects of season, weather, time of day, and habitat in order to statistically isolate the human predation effect. Encounters with the animals themselves as well as fresh signs of their activity allowed us to determine whether lower encounter rates in hunted zones are simply due to increased wariness by target species. Our results show that areas near hunters are hunted more frequently, and that Dasypus novemcinctus, Cebus apella, Tapirus terrestris, and Mazama spp. are all encountered at lower rates in those areas than in unhunted zones. We were unable to show that encounter rates with other important game species have been affected by human hunting. Demonstration of local depletion by central place foragers is expected, however, and cannot be used to conclude that prey species are in danger of regional extirpation.
Impacto de la Captura de Vertebrados Mayores en la Reserva de Mbaracayu, Paraguay
Datos de mas de 1,400,000 m de transectos en linea fueron colectados en colaboración con los indios Ache para determinar las tasas de encuentro con vertebrados mayores en la reserva Mbaracayu del Paraguay. Los datos fueron analizados usando regresión logística para determinar el impacto de la cazería sobre la tasa de encuentros en la reserva. El método fue controlado para aislar el efecto de la depredación humana de los efectos de la estación, el clima, la hora del día y el tipo de habitat. Los encuentros con animales, así como marcas frescas de su actividad nos permitieron determinar si las tasas bajas de encuentros en las zonas de caza son simplemente debidas al incremento en la alerta de las especies blanco. Nuestros resultados muestran que las áreas cercanas a los cazadores son utilizadas mas frecuentemente y que Dasypus novemcinctus, Cebus apella, tapirus terrestris y Mazama spp. se encuentran todos en menor proporción que en las áreas no utilizadas para la cazería. No pudimos demostrar que las tasas de encuentros con otras especies de caza importantes han sido afectadas por la caza humana. Esperamos una disminución local debida a la presencia de forrajeros centrales, aunque esto no puede ser utilizado para concluir que las especies de presas se encuentran en peligro de una extirpación regional.
We calculated extraction and production rates of bushmeat species in two main tropical, moist-forest regions, the Amazon and Congo basins. Extraction was estimated from the average number of animals consumed per person per year from anthropological studies that reported animal kills brought into settlements in the regions. W e calculated extraction rates (kg/km(2)/year) for 57 and 31 mammalian taxa In the Congo and Amazon, respectively. We then examined the sustainability of these extraction rates by basin and by taxa, using extraction-to-production (E:P) mass-balance equations. Production (tonnes/year) was calculated as the product of r(max)(the intrinsic rate of natural increase), mammal biomass, and total area of forest in each region. Species exploitation rates at specific body masses were significantly greater in the Congo than in the Amazon. The E:P ratio for the Congo was 2.4, 30 times the Amazon's ratio of 0.081. Thus, Congo Basin mammals must annually produce approximately 93% of their body mass to balance current extraction rates, whereas Amazonian mammals must produce only 4% of their body mass. We calculated sustainability levels derived from Robinson and Redford's harvest model for each taxa. On a basin-wide level, 60% and none of the mammal taxa in the Congo and Amazon basins, respectively were exploited unsustainably. To evaluate the effect of error on the estimates of E:P, we conducted a sensitivity analysis, which suggests that the mass-balance was most sensitive to error in standing stock but that our results are robust. We estimated that over 5 million tons of wild mammal meat feed millions in Neotropical (0.15 million) and Afrotropical (4.9 million),forests annually. Our Congo basin estimates are four times bigger than those calculated for the region by other workers, and we conclude that the current situation of bushmeat extraction in African rainforests is More precarious than previously thought.
We examine the abundance and distribution of Sumatran tigers (Panthera tigris sumatrae) and nine prey species in Bukit Barisan Selatan National Park on Sumatra, Indonesia. Our study is the first to demonstrate that the relative abundance of tigers and their prey, as measured by camera traps, is directly related to independently derived estimates of densities for these species. The tiger population in the park is estimated at 40–43 individuals. Results indicate that illegal hunting of prey and tigers, measured as a function of human density within 10 km of the park, is primarily responsible for observed patterns of abundance, and that habitat loss is an increasingly serious problem. Abundance of tigers, two mouse deer (Tragulus spp.), pigs (Sus scrofa) and Sambar deer (Cervus unicolor) was more than four times higher in areas with low human population density, while densities of red muntjac (Muntiacus muntjac) and pigtail macaques (Macaca nemestrina) were twice as high. Malay tapir (Tapirus indicus) and argus pheasant (Argusianus argus), species infrequently hunted, had higher indices of relative abundance in areas with high human density. Edge effects associated with park boundaries were not a significant factor in abundance of tigers or prey once human density was considered. Tigers in Bukit Barisan Selatan National Park, and probably other protected areas throughout Sumatra, are in imminent danger of extinction unless trends in hunting and deforestation are reversed.
Long-term studies in a 2,178ha fragment of semideciduous Atlantic Forest demonstrated important interactions between white-lipped
peccaries (Tayassu pecari) and the common palms, Syagrus romanzoffiana and Euterpe edulis. We conducted fruit removal and medium-to-large-sized mammalian exclusion experiments to: (1) quantify seasonal fruit consumption
from high-density patches beneath parent trees by T. pecari and other consumers, and (2) measure impacts of T. pecari rooting and foraging activities on seedling dynamics in E. edulis stands. A diverse array of fauna consumed S. romanzoffiana fruits. During the dry season, when S. romanzoffiana palms provided 68% of fruit dry weight in the fragment, T. pecari consumed significantly greater amounts than other consumers, and along with Pecari tajacu and Tapirus terrestris, were potential seed dispersers. The rodents, Sciurus ingrami and Agouti paca, consumed most S. romanzoffiana fruits in the wet season, acting as both seed dispersers and predators. More than 95% of E. edulis fruit removal was due to seed predation by T. pecari. Intense removal during the dry season was closely linked with previously documented range shifts and habitat preferences
by T. pecari. Exclusion plot experiments in E. edulis (palmito) stands showed that the number and proportion of nonpalmito (not E. edulis) seedlings increased dramatically in the absence of T. pecari rooting and foraging activities that disturbed soil and thinned seedlings. We discuss the importance of these ecosystem engineering
activities and palm-peccary trophic interactions for long-term maintenance of E. edulis stands and T. pecari populations, as well as water balance, in the forest fragment.
Comprehensive assessments of Paraguay's forest cover (FC) change from the 1970s to the 2000s using Landsat observations were conducted, including a wall-to-wall mapping of changes across the whole country between the 1990s and 2000s, and an assessment of forest area in the Atlantic Forest ecoregion in the 1970s using a systematic sampling approach. The derived wall-to-wall FC change map was evaluated using available high resolution satellite images and aerial photos. The overall accuracy values were 92% or higher in the areas covered by those high resolution data sets. The results revealed that the Atlantic Forest ecoregion experienced the most forest loss, with the 73.4% forest cover in the 1970s decreasing precipitously down to 40.7% by the 1990s and further down to 24.9% by the 2000s. The rapid loss of Atlantic forests was driven by complex social economic forces, including widespread land disputes arising from long time inequalities and profits from exporting agricultural products. Forest changes in the Humid Chaco and the Chaco ecoregions were relatively moderate. However, extensive forests were converted to non-forest land use near a major population center. The results also revealed that so far the established protected areas were effective in protecting forest within their border. However, most of the forests surrounding the protected areas were lost by the 2000s. Loss of Atlantic forest is a major threat to the rich biodiversity found in this region. The alarming deforestation rates over the last three decades and the low percentage of Atlantic forest left by the 2000s call for immediate actions to halt the trends of forest loss.
In the Argentine Chaco, the three species of peccaries (Artiodactyla) are likely affected by habitat destruction and hunting, yet basic information on peccary distribution and status in this region is poorly known. This study identifies human factors associated with relative abundance and distribution of each species. Estimation of relative abundance was based on interviews with local hunters, and variables potentially related to distribution and relative abundance of peccaries were estimated for 153 circular sample sites of 10 km diameter in the Argentine Chaco. Peccaries were found in sites of high forest cover, low human density, far from towns and with low density of roads. After accounting for forest cover and other variables, number of settlements was identified as the main variable negatively associated with relative abundance of the three species, which may be a result of local hunting. Density of roads was also negatively associated with presence of chacoan peccaries. Collared peccary seems to be the least susceptible to human perturbations. It was the most widely distributed and found in a wider range of conditions than the other species. Chacoan peccary was relatively rare. Because colonization and development programs are increasing in the region, areas still uninhabited should be protected, construction of roads controlled, and hunting managed.
Assessing Biodiversity Declines
Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation. Hoffmann et al. (p. 1503 , published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.
Soil is a physical, chemical, and biological medium at the upper surface of Earth’s land areas capable of accepting plant roots and thereby enabling plants to extend their photosynthetic tissues upward and intercept radiant energy from the sun. Each day, chemical and biological activities in soil change in response to temperature and moisture dynamics. Each soil has a range of physical, chemical, and biological properties determined by inherited mineral composition and biogeochemical processes existing in a quasi-steady state of flux. Most primary minerals in soil formed in geologic environments of high temperature and pressure. When exposed to lower temperatures and pressures, meteoric water, and organic compounds near Earth’s surface, primary minerals slowly decompose in response to weathering processes. As primary minerals weather, some elements necessary for plant growth are released as inorganic ions, some reassemble to form secondary silicate and oxide clay minerals, and some elements are lost via dissolution and leaching. After prolonged or intense weathering, few minerals containing elements necessary for plant growth remain. Weathering most often occurs in or slightly below the soil but may not be entirely related to the present soil. Material from which a present soil is formed may have been weathered in a soil environment, and eroded and deposited many times before coming to rest in its present location. Such materials are often almost devoid of nutrient- bearing minerals, and the soils formed provide scant amounts of the elements essential for plant growth. In contrast, minerals exposed to a soil environment for the first time on rapidly eroding slopes, fluvial deposits, or as volcanic ejecta succumb more rapidly to weathering and release essential elements in forms needed by plants. Plants ingest inorganic ions and water from the soil through their roots and combine them with carbon secured as carbon dioxide from the air, and with hydrogen and oxygen from water to form organic tissues. Organic residues are added to the soil as various plant parts, insects, and animals die. Microorganisms in and above the soil then decompose the organic residues, carbon returns to the air as carbon dioxide, and essential elements contained in the organic compounds are released as inorganic ions within the soil.
The Chacoan Peccary was thought extinct until it was rediscovered as a living species in the
Chaco region of Paraguay in the 1970s. At present, the region is going through an unprecedented
wave of deforestation, with over 1000 hectares of forest cleared daily. Wild populations of the
endangered Chacoan peccary are currently facing the fastest and most extensive habitat loss
ever recorded in recent history. To better understand the current conservation status we carried
out surveys and interviews throughout the species former range in the Chaco region of Paraguay.
From gathered location data, an ecological niche model was created using the Maxent program,
to create an updated distribution map. The model showed that most of the species former range
remains the same. However, the central southern portion of its range has suffered intense land
transformation, which has negatively affected the presence of the species. On the other hand, the
northern portion of its range, consisting of national parks and private lands that still mostly remain
undeveloped, currently has the highest probabilities of occurrence of Chacoan peccaries. Our
survey offers vital information, giving us the ability to create an updated species distribution map
for Paraguay. Helping identify habitat limits, boundaries and possible barriers as well as, specific
sites that need immediate attention. Similarly, our interviews have provided important information
that needs consideration when implementing conservation policies, management plans, or
community work to raise awareness regarding the importance of conserving the Chacoan
peccary and the rich Gran Chaco biodiversity.
We report results of a 2-year field study on the ecology of the endangered Chacoan peccary (Catagonus wagneri) in the Paraguayan Gran Chaco. Stable groups averaged 4.5 individuals. Two intensively tracked groups used ranges of 1,095-1,551 ha by minimum-convex polygons. Animals were active from dawn to dusk, with variations due to season, individual, and temperature. They travelled on average 2.2 km/day, not always returning to the same nightrest position. Ground cacti on which they fed were aggregated in infrequent patches scattered within their habitat of thorn forest. Daily ranges averaged 18.25 ha and were used on ca. 42-day cycles. Core areas were associated with cactus patches. Mutual avoidance between groups was indicated by low overlap of home ranges and the presence of scat stations. A dispersing group of one male and one female occupied three temporally and spatially discrete ranges, and moved 4.6 km over 9 months. The study area contained 0.43 individuals/km2. The population in the study area was in decline, explained by an annual mortality of 47% (five deaths recorded), probably low survival of young, a single farrowing season during the year, and a probable age of 2 years for first reproduction. We discuss implications of these results for conservation of the species.
Studies of published records and of about 36,900 specimens of native mammals from Bolivia reveal that at least 327 species occur there. Probably more than 20 other species, either new to science or new to Bolivia, remain to be discovered. In addition to these species names, some 44 additional subspecies names are used. Most of the subspecies names reflect taxonomic history more than detailed knowledge of geographic variation. In this report, the taxonomic status of each taxon within Bolivia is noted. Scientific names that have been used for Bolivian specimens are given for each species and subspecies, and all known publications that have specifically referred to Bolivian specimens are cited, along with a few other works selected for special reasons. Specimens are listed, and localities are mapped, including the prediction of the probable distribution of each species within Bolivia. Illustrated keys are based primarily on external, cranial, and dental characters and include 10 domestic and introduced species in addition to native species. The number of species present in most local areas ranges from about 50 to 180. Analysis indicates four major faunal areas: lowland tropics, lowland temperate zone (including the chacoan area), forested yungas, and highlands (altiplano). The highland and lowland faunas are almost mutually exclusive; the break between temperate and tropical is indistinct.
American marten (Martes americana), fisher (M, pennanti), wolverine (Gulo gulo), and lynx (Lynx lynx) are forest carnivores believed threatened by disturbance of late-successional forests. To manage forested ecosystems for these species, effective methods for their detection must be available. Recently, the U.S. Forest Service proposed standardized survey procedures for the detection of forest carnivores; this report presents the first critical assessment of these protocols. We compared dual sensor remote cameras and soot-coated open and covered track plates in the same study areas over an 8-month period. Of the 4 species targeted by these procedures, we detected 3 (American marten, fisher, wolverine). The remote camera method ranked highest with respect to ease of use, effectiveness, and accuracy of identifications. However, track plates performed well for 2 species and, under certain circumstances, may be the method of choice. We suggest improvements for each method and encourage that such standardized procedures be applied over wide regions.
The unsustainable harvest of wildlife is a major threat to global biodiversity and to the millions of people who depend on wildlife for food and income. Past research has called attention to the fact that commonly used methods to evaluate the sustainability of wildlife hunting perform poorly, yet these methods remain in popular use today. Here, we conduct a systematic review of empirical sustainability assessments to quantify the use of sustainability indicators in the scientific literature and highlight associations between analytical methods and their outcomes. We find that indicator type, continent of study, species body mass, taxonomic group and socio-economic status of study site are important predictors of the probability of reported sustainability. The most common measures of sustainability include population growth models, the Robinson & Redford (1991) model and population trends through time. Indicators relying on population-specific biological data are most often used in North America and Europe, while cruder estimates are more often used in Africa, Latin America and Oceania. Our results highlight both the uncertainty and lack of uniformity in sustainability science. Given our urgent need to conserve both wildlife and the food security of rural peoples around the world, improvements in sustainability indicators are of utmost importance.
Food habits of jaguar and puma were studied in two regions of the Paraguayan Chaco. Biochemical analysis of 280 scats attributed 106 to jaguar and 95 to puma. Overall dietary overlap was 65 percent and they shared six of seven main prey types. For both cats 43 percent of prey items and 15 percent of prey biomass taken were mammal species kg, 23 percent of items and 29 percent of the biomass were from species 1–15 kg, and 27 percent of items and 53 percent of the biomass were from larger species. Birds, reptiles, and insects made up the remainder. In a developed region no significant differences between their diets were found, while in an undeveloped area more small mammals were taken by both species, and jaguar took more large prey than puma. The potential roles of competition and of differences in habitat structure and prey availability between the two areas on these species’ diets are discussed.
Se estudiaron los hábitos alimenticios de jaguar y puma en dos regiones del Chaco paraguayo. A través de un análisis bioquímico de 280 heces se asignaron 106 a jaguar y 95 a puma. La superposición trófica total fue 65 por ciento y compartieron 6 de 7 items presa principales. Para ambos gatos las especies de mamíferos de < 1 kg fueron el 43 por ciento de los items presa y el 15 por ciento de la biomasa de presas consumidas, 23 por ciento de items y 29 por ciento de la biomasa fueron de especies de 1–15 kg y 27 por ciento de items y 53 por ciento de biomasa heron de especies mayores. El resto heron aves, reptiles e insectos. En una región desarrollada no se encontraron diferencias significativas entre las dietas, mientras que en una región no desarrollada ambas especies consumieron más pequeños mamíferos y los jaguares consumieron más presas grandes que puma. Se discuten los posibles roles en la dieta de estas especies de la competencia y de diferencias en la estructura del hábitat, y la disponibilidad de presas entre las dos áreas.
Summary 1. Many aspects of human behaviour impact on ecological systems. Ecologists therefore need information on changes in these behaviours and are increasingly using methods more familiar to social scientists. 2. Understanding patterns of wildlife harvesting is important for assessing the sustainability of harvests. Interviews are commonly used in which informants are asked to summarize their activities over a period of time. However, few studies have investigated the reliability of such data, the usefulness of interviews for monitoring trends, and how their information content can be maximized. 3. We carried out rapid assessment interviews with villagers in Madagascar about the quantity, timing and spatial patterns of crayfish Astacoides granulimanus and firewood collection. We compared the results with information from daily interviews with the same informants. We used mixed models to investigate how accurately people reported their activities in the rapid assessment interviews, and estimated the probability of detecting a change in harvesting from two such interviews using a Bayesian approach. 4. The interviews provided reliable information on quantities, effort, and the spatial pattern of harvesting. Simulations suggested the interviews would detect changes in catches and harvesting effort with reasonable power; for example, a 20% change in the amount of time spent crayfish harvesting could be detected with 90% power. Power is higher when the same informants are questioned in repeat interviews. 5. Synthesis and applications . Ecologists are increasingly using social techniques and it is vital that they are subject to rigorous testing to ensure robustness in trend detection. This study suggests that interviews can be used to monitor changes in harvesting patterns by resource users, but whether the power is adequate will depend on the needs of the study. To maximize the power of interviews, informants should be interviewed independently and the same informants interviewed in subsequent years.
A digital land cover map of South America has been produced using remotely sensed satellite data acquired between 1995 and the year 2000. The mapping scale is defined by the 1 km spatial resolution of the map grid-cell. In order to realize the product, different sources of satellite data were used, each source providing either a particular parameter of land cover characteristic required by the legend, or mapping a particular land cover class. The map legend is designed both to fit requirements for regional climate modelling and for studies on land cover change. The legend is also compatible with a wider, global, land cover mapping exercise, which seeks to characterize the world's land surface for the year 2000. As a first step, the humid forest domain has been validated using a sample of high-resolution satellite images. The map demonstrates both the major incursions of agriculture into the remaining forest domains and the extensive areas of agriculture, which now dominate South America's grasslands.
This paper analyses two processes acting on vegetation dynamics in the dry Chaco region of Argentina. The major one is the response of herbaceous/woody species to overgrazing. The second process is the dynamics of gallery forest resulting from intensive river-bed migrations which characterize the region. A main process model relates the largest and most frequent floods to the complex structure, high diversity and Amazonian lineage of the floristic composition of the forests. A model is presented which, by analysing river bank community dynamics in terms of the geomorphological instability (constant river-bed migration, river-bed filling, bank formation and disintegration), shows how the structure and composition of these forests would be determined by past floods rather than by the present one. -from Authors
Growing threats to biodiversity in the tropics mean there is an increasing need for effective monitoring that balances scientific rigor with practical feasibility. Alternatives to professional techniques are emerging that are based on the involvement of local people. Such locally based monitoring methods may be more sustainable over time, allow greater spatial coverage and quicker management decisions, lead to increased compliance, and help encourage attitude shifts toward more environmentally sustainable practices. Nevertheless, few studies have yet compared the findings or cost-effectiveness of locally based methods with professional techniques or investigated the power of locally based methods to detect trends. We gathered data on bushmeat-hunting catch and effort using a professional technique (accompanying hunters on hunting trips) and two locally based methods in which data were collected by hunters (hunting camp diaries and weekly hunter interviews) in a 15-month study in Equatorial Guinea. Catch and effort results from locally based methods were strongly correlated with those of the professional technique and the spatial locations of hunting trips reported in the locally based methods accurately reflected those recorded with the professional technique. We used power simulations of catch and effort data to show that locally based methods can reliably detect meaningful levels of change (20% change with 80% power at significance level [α]= 0.05) in multispecies catch per unit effort. Locally based methods were the most cost-effective for monitoring. Hunter interviews collected catch and effort data on 240% more hunts per person hour and 94% more hunts per unit cost, spent on monitoring, than the professional technique. Our results suggest that locally based monitoring can offer an accurate, cost-effective, and sufficiently powerful method to monitor the status of natural resources. To establish such a system in Equatorial Guinea, the current lack of national and local capacity for monitoring and management must be addressed.
Resumen: Las crecientes amenazas a la biodiversidad en los trópicos significan que hay una necesidad imperiosa de monitoreo efectivo que balancee el rigor científico con la factibilidad práctica. Están emergiendo alternativas a las técnicas profesionales que se basan en la participación de los habitantes locales. Tales métodos de monitoreo basados localmente pueden ser más sustentables con el tiempo, permiten mayor cobertura espacial y tomar decisiones de manejo más rápidamente, llevan a mayor cumplimiento y ayudan a estimular cambios hacia prácticas más sustentables ambientalmente. Sin embargo, pocos estudios han comparado los resultados o la rentabilidad de los métodos basados localmente con los de técnicas profesionales o investigado el poder los métodos basados localmente para detectar tendencias. Reunimos datos sobre el esfuerzo y la captura de la cacería de carne silvestre mediante una técnica profesional (acompañamiento de cazadores en viajes de cacería) y mediante dos métodos basados localmente en los que la información fue obtenida por cazadores (diarios de caza y entrevistas semanales a cazadores) en un estudio de 15 meses en Guinea Ecuatorial. Los resultados de esfuerzo y captura de los métodos basados localmente se correlacionaron fuertemente con los de la técnica profesional y los sitios espaciales de los viajes de cacería reportados en los métodos basados localmente reflejaron con precisión los registrados con la técnica profesional. Utilizamos simulaciones del poder de datos de esfuerzo y captura para demostrar que los métodos basados localmente pueden detectar niveles de cambio confiables y significativos (cambio de 20% con 80% de poder en un nivel de significancia [α]= 0.05) en la captura por unidad de especies. Los métodos basados localmente fueron los más rentables para el monitoreo. Las entrevistas a cazadores recolectaron datos de esfuerzo y captura de 240% más cacerías por persona/hora y 94% más cacerías por unidad de costo que la técnica profesional. Nuestros resultados sugieren que el monitoreo basado localmente puede ofrecer un método preciso, rentable y suficientemente poderosos para monitorear el estatus de los recursos naturales. Para establecimiento de tal sistema en Guinea Ecuatorial se debe atender la escasez de capacidad nacional y local para el monitoreo y manejo.
Mazama gouazoubira. The IUCN Red List of Threatened Species
- P A Black-Decima
- A Vogliotti
Managing wildlife with local communities in the Peruvian Amazon: the case of the Reserva Comunal Tamshiyacu-Tahuayo
- Bodmer
Subsistence hunting by three ethnic groups of the Lacandon Forest
- Naranjo
Terrestrial ecoregions of the world: a new map of life on earth. A new global map of terrestrial ecoregions provides an innovative tool for conserving biodiversity
- Olson
Atlas Geografico del Chaco Paraguayo
- Red de Inversiones y Exportaciones, U.G
Why neotropical forest ungulates matter
- Taber
The IUCN Red List: a key conservation tool
- Vié