Guanaco Abundance Research Articles

Is tourism impacting pumas in the Torres del Paine UNESCO Biosphere Reserve in southern Chile?

Ecotourism generates $7.6 trillion annually and supports 292 million jobs around the world, and because of these benefits, it has been emphasized as a conservation strategy. Ecotourism, however, is not the solution for every community, and there is growing evidence that tourism can have unintended consequences for local people and wildlife, unless well managed. Here, we assessed the relative impacts of anthropogenic activities related to tourism (e.g. road density, distance to ranches and camping areas) and prey distributions on puma occupancy and abundance in the open steppe habitat of the southeast portions of the Torres del Paine UNESCO Biosphere Reserve, where pumas are protected. In winter, puma abundance and occupancy were explained by both prey and anthropogenic metrics. In summer, puma abundance was explained by both prey and anthropogenic metrics, but occupancy only by anthropogenic metrics. Across both periods, puma abundance was only explained by anthropogenic metrics, and occupancy was explained by both prey and anthropogenic metrics. Guanacos, the most important prey species for local pumas, never appeared in any top model, except in summer, during which puma abundance was explained by lower not higher guanaco abundance. Not unexpectedly, puma abundance and occupancy were negatively correlated with trail and road density across all analyses. In the high tourism season of summer, roads had 2–3 times the impact on puma abundance than prey metrics in top models. During our study, the average number of monthly visitors per month in summer (November-January) was 892 % higher than winter (May- July). As a whole, we believe our analyses suggest that tourism may be negatively impacting pumas, but the severity of this impact remains questionable. Future work should include studying stress in puma populations experiencing heavy tourism, simultaneous with the work needed to understand relative thresholds of impact on puma fitness metrics (e.g. survival, hunting success). We believe our work also highlights the need for standards and guidelines to be created and adopted among those involved in puma tourism in Torres del Paine and beyond.

Human–wildlife conflicts in Patagonia: ranchers’ perceptions of guanacoLama guanicoeabundance

AbstractConflicts between people and wildlife have become widespread as people move to areas previously home to wildlife and as wild populations recover. In Patagonia, one of the main threats to guanacoLama guanicoeconservation is the animosity of sheep ranchers towards the species. As key stakeholders in guanaco conservation we assessed ranchers’ perceptions regarding guanaco abundance in Isla Grande de Tierra del Fuego, Argentina. We contrasted these perceptions with estimated guanaco abundance and explored the socio-ecological factors influencing perceptions and how perceptions of overabundance are rooted in contextual factors rather than actual abundance. We performed semi-structured interviews with ranchers from Isla Grande and estimated guanaco abundance independently using density surface modelling. Ranchers were divided into three categories depending on their perception of guanaco abundance: ‘too many’, ‘many’ and ‘normal’. Those in the ‘many’ and ‘normal’ categories perceived guanaco abundance as being similar to actual abundance, whereas those in the category ‘too many' overestimated guanaco abundance. The perceived issues affecting livestock production varied between categories, although feral dogs emerged as the main problem. Negative perceptions of the guanaco stemmed from ranchers' beliefs that the species reduces forage availability for livestock, and from their disappointment about the government's handling of concerns regarding livestock production. Greater understanding and integration of the human dimension in conservation are needed to design more inclusive and resilient management plans.

Direct and indirect effects of roads on activity patterns of the largest South American artiodactyl (Lama guanicoe) in a hyper-arid landscape

The effects of roads on natural environments have been studied in many places around the world. The presence of roads can be considered for native animals as a disturbance stimulus. Besides, roads can facilitate arrival and entry of alien species, such as domestic and feral ungulates, which sometimes compete with native species. Due to this, we assessed if the presence of roads affect directly or indirectly, through the presence of non-native ungulates, the activity patterns of the guanaco, a native ungulate. Sampling was conducted during three years, in two types of roads. We used camera traps at different distances from these infrastructures. We found that the abundance of guanacos was not affected by that of non-native ungulates, but it was higher in the dry than in the wet season. In relation to activity patterns, the guanaco showed a diurnal activity pattern with an activity peak at 12:00 h. Moreover, donkeys showed cathemeral activity pattern, whereas cattle had the same activity pattern as guanacos, causing a switch to bimodal activity pattern of guanacos in the presence of cattle. We proved an indirect effect of roads, a temporal segregation of guanacos probably caused by cattle. Our results demonstrate that the activity pattern of guanacos changes from unimodal to bimodal near the paved road, probably due to the high abundance of cattle near these areas. Our findings also highlight the need for further studies to discriminate between direct and indirect effects of roads on wildlife in South American deserts.

Choosing what is left: the spatial structure of a wild herbivore population within a livestock-dominated landscape.

Shrublands and grasslands comprise over 30% of the land surface and are among the most exploited ecosystems for livestock production. Across natural landscapes, the distribution and abundance of wild herbivores are affected by interspecific competition for foraging resources, hunting and the development of infrastructure among other factors. In Argentine Patagonia, the abundance of domestic sheep grazing on native vegetation outnumbers the widely distributed guanaco (Lama guanicoe) and sheep ranching monopolizes the most productive lands. In this work, we aimed to assess the spatial variation in the abundance of guanacos in Península Valdés, a representative landscape of Patagonia, investigating the incidence of natural and human-related factors. We conducted ground surveys during the austral autumn in 2017 totaling 383.4 km along areas with and without sheep ranching. We built density surface models to account for the variation in guanaco abundance and obtained a map of guanaco density at a resolution of 4 km2. We estimated an overall density of 11.71 guanacos.km−2 for a prediction area of 3,196 km2, although the density of guanacos tripled in areas where sheep ranching was terminated (in around 20% of the surface of Península Valdés) compared to areas with sheep. Guanacos were more abundant at lower values of primary productivity and sheep stocking rates and further from inhabited ranch buildings, suggesting competition with sheep and conflict with humans. Although guanacos selected open, grass-dominated habitats across sheep-free sites, fences dividing properties and paddocks played a significant role in the spatial structure of their population in Península Valdés affecting negatively the abundance of guanacos. Our results indicate that actions to improve habitat connectivity for guanacos, favor the coexistence among guanacos and sheep ranching, and promote responsible human activities and attitudes towards wildlife are needed.

Modelling the abundance and productivity distribution to understand the habitat–species relationship: the guanaco (Lama guanicoe) case study

Abstract ContextThe conservation of large wild herbivores presents a challenge posed by the fact that their broad habitat requirements overlap with various human activities. Elucidating the factors that explain their distribution patterns provides us with a better understanding of habitat–species relationships and facilitates the design of effective management policies. AimsIdentify the natural (forage availability, weather) and anthropogenic (hunting, interspecific competition) factors that explain the abundance and productivity distribution of the guanaco. Estimate guanaco abundance and productivity and describe their distribution. MethodsWe estimated the abundance and productivity of guanaco by using aerial surveys during the breeding and non-breeding season of two consecutive years, following the strip-transect methodology; we then modelled these as a function of environmental factors by means of density surface models. Key resultsThe highest abundance and productivity of guanaco occurred mostly where mesic grassland was dominant. Guanaco abundance presented three hotspots on the basis of geographic location, and family groups were more productive at low to intermediate livestock level. Abundance was significantly higher in the breeding season for both years (5614 and 14092 individuals) than in the non-breeding season (2922 and 6926 individuals), and it was higher in 2015 than in 2014. Productivity was higher in 2015 than in 2014 (0.54 and 0.46 calves per adult respectively). ConclusionsGuanaco responded to forage availability, occupying zones with low to intermediate food availability in the breeding season, and those with the highest availability in the non-breeding season. This could be due to interspecific competition between livestock and guanaco family groups. We propose that the overall guanaco response could also be explained by social structure or by unassessed factors such as predation risk by feral dogs. ImplicationsThe guanaco could compensate for the use of habitats with a lower food availability during the breeding season by using better-quality habitats during the non-breeding season.

Diffusive dispersal in a growing ungulate population: guanaco expansion beyond the limits of protected areas

Growth of wild ungulate populations within protected areas can cause an expansion towards surrounding non-protected areas and lead to conflicts with human activities. The spatial and demographic structure of colonizing populations inform about their state and potential trends, since the initial colonization by dispersing individuals precedes the establishment of a population with potential for further growth and expansion. Once colonization has succeeded, the spatial pattern of animal abundance is associated with intra- and interspecific interactions and environmental factors (e.g., habitat and food availability) and the population shows similar demographic features throughout the whole occupation area, which has been called a diffusive dispersal pattern. Here, we analyze the current status of colonization by a guanaco population of ranches surrounding a protected area in Chilean Patagonia with data gathered along three consecutive years. We thus compared animal abundance and social structure between the protected and unprotected areas and evaluated throughout the whole area the effect of environmental factors on guanaco abundance, proportion of family groups, and reproductive success. Guanaco abundance significantly declined with increasing distance from the center of the local distribution and marginally with predation risk. Moreover, social structure showed only minor differences between areas, pointing to a diffusive dispersal pattern. These results suggest that the population is already well established and has the potential to grow and continue its expansion. The case exemplifies a challenging outcome of successful animal conservation, and it presents a useful approach to evaluate the state of wild ungulate populations colonizing new areas.

Guanaco abundance and monitoring in Southern Patagonia: distance sampling reveals substantially greater numbers than previously reported.

Guanacos (Lama guanicoe) are thought to have declined in Patagonia mainly as a result of hunting and sheep ranching. Currently accepted estimates of total population size are extrapolated from densities obtained through strip transects in local studies. We used road surveys (8,141 km) and distance sampling to estimate guanaco density and population size over major environmental gradients of Santa Cruz, a large region in southern Patagonia. We also calculated the survey effort required to detect population trends in Santa Cruz. We found considerable spatial variation in density (1.1 to 7.4 ind/km2), with a mean value of 4.8 ind/km2, which is more than twice the mean value guessed for central and northern Patagonia. Consequently, guanaco numbers in Santa Cruz were estimated at 1.1 million individuals (95% CI 0.7 to 1.6), which almost doubles current estimates of guanaco population size in South America. High guanaco abundance was found in arid lands, overgrazed and unable to support profitable sheep stocks. Detecting a 50% change in guanaco population size over a 10-year period requires substantial monitoring effort: the annual survey of between 40 and 80 30-km transects, which becomes up to 120 transects if trends are to be detected over 5 years. Regional patterns in guanaco density can only be detected through large-scale surveys. Coupling these surveys with distance sampling techniques produce robust estimates of density and its variation. Figures so obtained improve currently available estimates of guanaco population size across its geographic range, which seem to be extrapolated from strip counts over small areas. In arid lands degraded by sheep overgrazing, sustainable use of guanaco populations would help harmonize guanaco conservation, socio-economic progress of rural areas, and eventually the restoration of shrub-steppes.

Effects of livestock on guanacoLama guanicoedensity, movements and habitat selection in a forest–grassland mosaic in Tierra del Fuego, Chile

AbstractLocally abundant ungulates often come into conflict with human activities. After a population collapse that reached its nadir in the 1970s, the guanacoLama guanicoepopulation in Tierra del Fuego, Chile, recovered and is now in conflict with sheep ranching and commercial logging. We studied the effects of livestock density and environmental factors on guanaco abundance and spatial ecology, using seasonal counts and radio-telemetry in a private protected area (Karukinka) and neighbouring ranches in a forest–grassland mosaic in Tierra del Fuego. Guanaco density was highest in low-elevation areas with more grassland cover and little snow accumulation in winter. In low-elevation areas, guanaco density decreased with increasing livestock density. Radio-tracked guanacos exhibited a partial migration pattern: two individuals migrated seasonally, selecting grasslands and avoiding forests mainly in summer, whereas six sedentary individuals used habitats according to their availability. Migratory guanacos spent the summer in Karukinka and winter on nearby ranches. High sheep densities and poor range condition on the ranches reduce key forage resources available to guanacos and may promote use of forests by guanacos, affecting forest regeneration and increasing conflict with logging. Current guanaco harvest by loggers may fail to reduce the impact of guanacos on logged-forest regeneration if guanaco spatial ecology and sheep management are not considered. Our results provide insight into the interactions among guanacos, forests and livestock ranching, and may be used to reduce conflicts and guide conservation in the Fuegian ecosystem.

Ecological Correlates of Group-Size Variation in a Resource-Defense Ungulate, the Sedentary Guanaco

For large herbivores, predation-risk, habitat structure and population density are often reported as major determinants of group size variation within and between species. However, whether the underlying causes of these relationships imply an ecological adaptation or are the result of a purely mechanistic process in which fusion and fragmentation events only depend on the rate of group meeting, is still under debate. The aim of this study was to model guanaco family and bachelor group sizes in contrasting ecological settings in order to test hypotheses regarding the adaptive significance of group-size variation. We surveyed guanaco group sizes within three wildlife reserves located in eastern Patagonia where guanacos occupy a mosaic of grasslands and shrublands. Two of these reserves have been free from predators for decades while in the third, pumas often prey on guanacos. All locations have experienced important changes in guanaco abundance throughout the study offering the opportunity to test for density effects. We found that bachelor group size increased with increasing density, as expected by the mechanistic approach, but was independent of habitat structure or predation risk. In contrast, the smaller and territorial family groups were larger in the predator-exposed than in the predator-free locations, and were larger in open grasslands than in shrublands. However, the influence of population density on these social units was very weak. Therefore, family group data supported the adaptive significance of group-size variation but did not support the mechanistic idea. Yet, the magnitude of the effects was small and between-population variation in family group size after controlling for habitat and predation was negligible, suggesting that plasticity of these social units is considerably low. Our results showed that different social units might respond differentially to local ecological conditions, supporting two contrasting hypotheses in a single species, and highlight the importance of taking into account the proximate interests and constraints to which group members may be exposed to when deriving predictions about group-size variation.

Response of guanacosLama guanicoeto changes in land management in Península Valdés, Argentine Patagonia: conservation implications

AbstractThe guanacoLama guanicoewas the only large native herbivore widely distributed across Patagonia until the introduction of domestic sheepOvis aries. Guanacos have declined because of competition with sheep for forage, high hunting pressure and habitat degradation. Península Valdés is a protected area where sheep ranching is the predominant activity. A ranch formerly dedicated to sheep production was converted into a private wildlife reserve, from which all the sheep were removed in 2005. We studied changes in guanaco abundance inside and outside the reserve after sheep removal, and also plant cover of various vegetation types. We found that guanaco abundance was higher inside than outside the reserve, and increased by three-fold within 3 years. Total plant cover and grass cover were higher inside than outside the reserve. Our results showed that guanacos reacted rapidly to changes in management, and suggest that even at a high density guanacos would not be as damaging to the vegetation as sheep. Although management changes resulted in significant changes in guanaco abundance locally, the size of a protected area influences the persistence of wild populations. A large herbivore such as the guanaco needs to be managed across large areas. We believe it is necessary to implement a management plan for Península Valdés that allows for the coexistence of sustainable livestock production and healthy wildlife populations.

Habitat use by guanacos (Lama guanicoe, Camelidae) in northern Patagonia (Mendoza, Argentina)

Strategies of habitat use of the guanaco were analyzed in early and late summer, when parturition and lactation increase nutritional needs and predation risk. The daily distribution of guanacos was followed by scan‐sampling, relief and soil were measured in each habitat, and vegetation was analyzed by the point‐quadrat method. Guanacos showed a selective habitat use, preferring open areas with grasslands, gentle terrain and low hiding cover. The density of guanacos was positively associated with the intensively eaten grass Panicum urvilleanum, and negatively associated with rocky soils, high shrublands and avoided plants. A weakening of the selective habitat use occurred when the abundance of guanacos increased in the study area during late summer, ceasing avoidance of poor and risky habitats.

Habitat use and social structure of an isolated population of guanacos (Lama guanicoe) in the Monte Desert, Argentina

We studied abundance, habitat use and social structure of an isolated population of guanacos in the Lihue Calel National Park in central Argentina, based on data from foot surveys during 1998–2000. Based on topography and vegetation characteristics we distinguished three types of habitat: hills, valleys and piedmonts, and lowlands. Three types of social groups were observed: solitary males, family groups and male groups. The guanacos used hills preferentially, followed by valley and piedmont. The guanacos avoided the lowlands where the vegetation is dense. Habitat selection, both on a coarse and a fine scale, could be explained by habitat quality and possibly also predator avoidance behaviour. Abundance of guanacos increased by 21% over the 3-year-study period. However, the specificity of habitat requirements of guanacos and the susceptibility of the study area to wildfires could cause guanacos to move into sub-optimal areas were they are more vulnerable to predation and human persecution.

Browsing by guanaco ( Lama guanicoe) on Nothofagus pumilio forest gaps in Tierra del Fuego, Chile

The presence of guanaco ( Lama guanicoe, Muller 1776, Camelidae) in forests of Nothofagus pumilio (Poepp. et Endl.) Krasser. (lenga) in Tierra del Fuego has been associated with browsing damage in the regeneration of these forests, but little quantitative data are available. In developing and implementing forest management plans for N. pumilio forests, the effects of guanaco browsing are a major source of variation in attaining regeneration and growth goals, however, guanaco is not generally accounted for in management planning in the region. In this study we examined the browsing damage levels of guanaco and introduced livestock on N. pumilio regeneration occurring in canopy gaps of forests in Tierra del Fuego, Chile (54°12′S, 68°45′W). Relationships were established between browsing levels and gap characteristics like gap size, gap age and abundance of regeneration. Results indicated that 88.7% of regeneration growing in gaps experienced some degree of damage by browsing, and that the degree of damage was higher in smaller gaps, which might depend on the size of guanaco herds. We also found that the degree of damage was positively related with the abundance of guanacos. However, no relationship was found between gap size and abundance of guanacos.

Guanacos and sheep: evidence for continuing competition in arid Patagonia

Guanacos (Lama guanicoe) are the only wild ungulate species widely distributed across the Patagonian steppe and have undergone a precipitous population decline since the introduction of domestic sheep (Ovis aries) 100years ago. There has been speculation that sheep ranching may have played a major role in guanaco population decline after monopolising the most productive land because of competition for forage plants. Our aim in this work was to estimate guanaco abundance and account for its variation across nine different sites, two seasons and two years. We conducted over 100 ground surveys of both guanacos and sheep and estimated the availability of the preferred plant species both animal species might select in their diet. We found that (1) sheep densities were up to 23 times higher than guanaco densities in sympatric conditions, (2) at a protected site without sheep, guanaco density was one order of magnitude higher than at the rest of the sites, (3) across nine different sites, sheep densities alone accounted for around 60% of the variation in guanaco abundance, (4) guanaco densities were negatively related to both total plant cover and availability of the preferred plant species in their diet, which were both positively associated with sheep density, and (5) within-site changes in guanaco densities between seasons and years were negatively related to changes in sheep densities. Our results are consistent with predictions on interspecific competition for food resources, although we cannot rule out possible effects of other human-related activities influencing guanaco abundance. We conclude that sheep compete with guanacos for forage in arid Patagonia.

Diet and abundance of the guanaco (Lama guanicoeMüller 1776) in four habitats of northern Patagonia, Argentina

Guanaco responses to spatial heterogeneity were evaluated in La Payunia Protected Area, Patagonia, through analysis of guanaco diet and density, and food availability, in four habitats. An opportunistic behaviour was suggested by dietary differences among habitats reflecting differences in availability of food plant species. The abundance of guanacos was positively correlated with the availability of the preferred species, and it was stable throughout the year where preferred shrubs were highly available. Switching among habitats may be an adaptive response of guanacos to the low quality of available food. A strong negative influence of the range livestock on the abundance of guanacos, in spite of high food availability, was detected.