Scielo RSS <![CDATA[Revista chilena de historia natural]]> http://www.scielo.cl/rss.php?pid=0716-078X20140001&lang=pt vol. 87 num. lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<b>Rolling Pampas agroecosystem</b>: <b>which landscape attributes are relevant for determining bird distributions?</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100001&lng=pt&nrm=iso&tlng=pt BACKGROUND: Agricultural intensification is among the main factors affecting biodiversity. The Rolling Pampas of Argentina have undergone through a process of landscape transformation and agricultural intensification that altered avian diversity patterns. Grassland area loss is argued to be the main reason for grassland bird species declines, but there is a lack of studies that compare cropland vs. pastures including other landscape features as determinants of species richness and distribution. Also, it is needed to understand how these relations are modified at different spatial scales. In this study, we explored how species are associated to different landscape attributes and elements like land use, roadside vegetation, trees, homesteads, and water bodies. Our aim was to explore how bird species are associated to the new elements of the Pampas agroecosystem at different spatial scales to reveal which are important for avian management. RESULTS: We ran field surveys covering a range of land use and landscape complexity, defined by the variety of component features. We performed canonical correspondence and diversity partition analyses to determine the association of species with land use, landscape complexity, and particular anthropogenic elements. Our results show that land use type is an important driver of bird species distributions, but it is also controlled by the presence of trees, houses, and water bodies that provide nesting and food resources. Simple landscapes have higher species turnover rates (beta diversity) than complex ones with similar gamma diversity, demonstrating that the effect of landscape simplification on bird diversity differs across spatial scales, leading to different possible management and conservation strategies. CONCLUSIONS: New approaches are needed to manage agroecosystems for avian conservation. We need to take pragmatic approaches, and in highly disturbed ecosystems, anthropic elements have to be included as constituent parts of the system. <![CDATA[<b>Latitudinal diversity patterns of Chilean coastal fishes</b>: <b>searching for causal processes</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100002&lng=pt&nrm=iso&tlng=pt BACKGROUND: Several particular aspects of diversity patterns of Chilean littoral fishes are still poorly understood, and existing studies within this scope are fundamentally based on bibliographic compilations. In this study, we use empirical data to assess whether the diversity patterns of fish fauna along 4000 km of the Chilean coast (20° - 55° S)can be explained in relation to the environmental latitudinal gradient. Fish were collected from intertidal pools and subtidal habitats (<35 m). Analyses focused on the spatial scales of diversity patterns and latitudinal breaks in species diversity, comparing the observed patterns among intertidal and subtidal habitats. Correlations between variance in environmental factors and species richness were calculated. RESULTS: Richness was positively autocorrelated at spatial scales <1000 km. Overall, richness was observed to progressively decrease toward higher latitudes, but values for intertidal fish in particular decreased towards the north and south from the point of maximum richness. This is a pattern that has already been recorded for other intertidal organisms. Similarity was seen to decrease with distance, and turnover point for intertidal fishes was high around 30° - 32° S, while northern species disappeared between 36° - 39° S. Subtidally, there is an invasion of subantarctic species between 53° - 55° S. CONCLUSIONS: Environmental variables are significant to the diversity patterns recorded. However, richness variations could result from many types of variables acting together and not from one single factor. <![CDATA[<b>A new population of Darwin's fox (<i>Lycalopex fulvipes</i>) in the Valdivian Coastal Range</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100003&lng=pt&nrm=iso&tlng=pt BACKGROUND: Several particular aspects of diversity patterns of Chilean littoral fishes are still poorly understood, and existing studies within this scope are fundamentally based on bibliographic compilations. In this study, we use empirical data to assess whether the diversity patterns of fish fauna along 4000 km of the Chilean coast (20° - 55° S)can be explained in relation to the environmental latitudinal gradient. Fish were collected from intertidal pools and subtidal habitats (<35 m). Analyses focused on the spatial scales of diversity patterns and latitudinal breaks in species diversity, comparing the observed patterns among intertidal and subtidal habitats. Correlations between variance in environmental factors and species richness were calculated. RESULTS: Richness was positively autocorrelated at spatial scales <1000 km. Overall, richness was observed to progressively decrease toward higher latitudes, but values for intertidal fish in particular decreased towards the north and south from the point of maximum richness. This is a pattern that has already been recorded for other intertidal organisms. Similarity was seen to decrease with distance, and turnover point for intertidal fishes was high around 30° - 32° S, while northern species disappeared between 36° - 39° S. Subtidally, there is an invasion of subantarctic species between 53° - 55° S. CONCLUSIONS: Environmental variables are significant to the diversity patterns recorded. However, richness variations could result from many types of variables acting together and not from one single factor. <![CDATA[<b>Conservation of biodiversity in private lands</b>: <b>are Chilean landowners willing to keep threatened species in their lands?</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100004&lng=pt&nrm=iso&tlng=pt BACKGROUND: The biological conservation in private lands largely depends upon landowners' willingness to keep populations of wild species on them, an issue highlighted by the Convention on Biological Diversity. In this study, we aim (i) to understand small landowners' behavioural intentions, or relative intensity to adopt a given behaviour, towards threatened wildlife and (ii) to assess the role of local ecological knowledge, awareness of protected area, and forest ownership on landowners' behavioural intentions towards threatened biodiversity. We interviewed peasants living around Los Queules National Reserve in Central Chile. RESULTS: Interview results showed that behavioural intentions towards threatened species were species-dependant. Results also showed that higher ecological knowledge and awareness of a protected area were associated with positive behavioural intentions towards wildlife. Peasants who owned land with larger forest cover reported positive behavioural intentions towards wildlife more frequently than peasants with less forest cover on their lands, although associations were not consistent across species. CONCLUSIONS: We conclude that (i) opportunities for getting peasants to support species conservation depend on the particular species and vary across peasants and (ii) there is a relevant social heterogeneity among peasants in terms of behavioural intentions towards species. As both factors likely influence conservation outcomes, they should be considered in the design of biodiversity conservation efforts. <![CDATA[<b>Temporal and spatial variation of the pollinator assemblages in <i>Alstroemeria ligtu</i> (Alstroemeriaceae)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100005&lng=pt&nrm=iso&tlng=pt BACKGROUND: The biological conservation in private lands largely depends upon landowners' willingness to keep populations of wild species on them, an issue highlighted by the Convention on Biological Diversity. In this study, we aim (i) to understand small landowners' behavioural intentions, or relative intensity to adopt a given behaviour, towards threatened wildlife and (ii) to assess the role of local ecological knowledge, awareness of protected area, and forest ownership on landowners' behavioural intentions towards threatened biodiversity. We interviewed peasants living around Los Queules National Reserve in Central Chile. RESULTS: Interview results showed that behavioural intentions towards threatened species were species-dependant. Results also showed that higher ecological knowledge and awareness of a protected area were associated with positive behavioural intentions towards wildlife. Peasants who owned land with larger forest cover reported positive behavioural intentions towards wildlife more frequently than peasants with less forest cover on their lands, although associations were not consistent across species. CONCLUSIONS: We conclude that (i) opportunities for getting peasants to support species conservation depend on the particular species and vary across peasants and (ii) there is a relevant social heterogeneity among peasants in terms of behavioural intentions towards species. As both factors likely influence conservation outcomes, they should be considered in the design of biodiversity conservation efforts. <![CDATA[<b>At-sea abundance and distribution of skuas and jaegers (Charadriiformes: Stercorariidae) at coastal waters off central Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100006&lng=pt&nrm=iso&tlng=pt BACKGROUND: Skuas and jaegers (Charadriiformes: Stercorariidae) are seabirds breeding at moderate to high latitudes and some perform extensive post-breeding transequatorial migrations. Most species overwinter and perform significant portions of their migratory flyways along the Pacific coast of South America, but scant information is available on their at-sea ecology in this waters. Our aims in this study were to determine: 1) the timing of occurrence and fluctuations in abundance of skua and jaeger species, 2) their spatial distribution within the coastal zone and 3) at-sea behavior of birds, including flock size and interactions with other seabird species. RESULTS: Between July 2006 and October 2013, we conducted at-sea bird counts at Valparaiso Bay (33°S) in central Chile and confirmed the occurrence of Chilean skuas (Stercorarius chilensis), Brown skuas (S. antarcticus), and Parasitic jaegers (S. parasiticus). Parasitic jaegers are regular austral summer visitors (November to March), whereas Brown skuas occur in the area only in winter (July to October). Chilean skuas were regularly recorded year-round in the area with higher abundances between late winter and early spring (August to October). Brown and Chilean skuas where observed comparatively offshore, whereas Jaegers presented a more coastal distribution, probably associated to host presence. Chilean skuas kleptoparasitized similar-sized (shearwaters and fulmars) and larger seabird species (boobies), whereas jaegers chased only smaller coastal birds (gulls and terns). Brown skuas engaged in no kleptoparasitic behaviors. All three species were observed mostly as solitary individuals. CONCLUSIONS: Skuas and jaegers showed in general a marked seasonality in their occurrence and abundance (only Chilean skua occurs year-round) and use this area as a commuting and stopover zone within their extensive migratory flyway along the southeastern Pacific. <![CDATA[<b>Pollination ecology and breeding system of two<i> Calceolaria</i> species in Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100007&lng=pt&nrm=iso&tlng=pt BACKGROUND: Skuas and jaegers (Charadriiformes: Stercorariidae) are seabirds breeding at moderate to high latitudes and some perform extensive post-breeding transequatorial migrations. Most species overwinter and perform significant portions of their migratory flyways along the Pacific coast of South America, but scant information is available on their at-sea ecology in this waters. Our aims in this study were to determine: 1) the timing of occurrence and fluctuations in abundance of skua and jaeger species, 2) their spatial distribution within the coastal zone and 3) at-sea behavior of birds, including flock size and interactions with other seabird species. RESULTS: Between July 2006 and October 2013, we conducted at-sea bird counts at Valparaiso Bay (33°S) in central Chile and confirmed the occurrence of Chilean skuas (Stercorarius chilensis), Brown skuas (S. antarcticus), and Parasitic jaegers (S. parasiticus). Parasitic jaegers are regular austral summer visitors (November to March), whereas Brown skuas occur in the area only in winter (July to October). Chilean skuas were regularly recorded year-round in the area with higher abundances between late winter and early spring (August to October). Brown and Chilean skuas where observed comparatively offshore, whereas Jaegers presented a more coastal distribution, probably associated to host presence. Chilean skuas kleptoparasitized similar-sized (shearwaters and fulmars) and larger seabird species (boobies), whereas jaegers chased only smaller coastal birds (gulls and terns). Brown skuas engaged in no kleptoparasitic behaviors. All three species were observed mostly as solitary individuals. CONCLUSIONS: Skuas and jaegers showed in general a marked seasonality in their occurrence and abundance (only Chilean skua occurs year-round) and use this area as a commuting and stopover zone within their extensive migratory flyway along the southeastern Pacific. <![CDATA[<b>Mesophyll conductance constrains photosynthesis in three common sclerophyllous species in Central Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100008&lng=pt&nrm=iso&tlng=pt BACKGROUND: Quillaja saponaria Mol., Cryptocarya alba Mol. Looser, and Lithraea caustica Molina Hook et Arn., are common sclerophyllous species in Mediterranean Central Chile. Mesophyll conductance, g m, may strongly limit photosynthesis in these semiarid environments. RESULTS: Simultaneous measurements of gas exchange and chlorophyll fluorescence were carried out in 45 nursery plants from these species to determine diffusional and biochemical limitations to photosynthesis. Values of stomatal conductance, g s, were greater than those of mesophyll conductance, g m, while their ratio (g m/g s) was not influenced by species being on average 0.47. Relative limitations posed by mesophyll conductance to photosynthesis, Lm, (0.40 ± 0.02) were high compared to those imposed by stomata, Ls (0.07 ± 0.01). The average CO2 concentration in the intercellular air spaces (Ci) was 32 µmol mol-1 lower than in the atmosphere (Ca), while the average CO2 concentration in the chloroplasts (Cc) was 131 µmol mol-1 lower than Ci independent of species. Maximal rates of Rubisco carboxylation, Vcmax, and maximal electron transport rates driving regeneration of RuBP, Jmax, ranged from 13 to 66 µmol CO2 m-2 s-1 and from 33 to 148 µmol electrons m-2 s-1, respectively, and compare well to averages for C3 plants. CONCLUSIONS: Photosynthetic performance was in the series: Q. saponaria > C. alba ≥ L. caustica, which can be attributed first to mesophyll conductance limitations, probably mediated by leaf anatomical traits and then to species specific foliage N partitioning strategies. <![CDATA[<b>Arbuscular mycorrhizal fungi associated with the rhizosphere of seedlings and mature trees of <i>Swietenia macrophylla</i> (Magnoliophyta: Meliaceae) in Los Tuxtlas, Veracruz, Mexico</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100009&lng=pt&nrm=iso&tlng=pt BACKGROUND: Big-leaf mahogany (Swietenia macrophylla King) is the woody species with the highest economic value in Latin America. Currently, it is subject to intensive exploitation, diminishing its natural populations. Due to this decline, the species is a preferred species for reforestation and establishment of commercial tropical plantations. Mycorrhizal symbiosis is a biotic factor scarcely studied in the ecology of this species. Therefore, the objective of this research was to identify the diversity of arbuscular mycorrhizal fungi (AMF) species associated with the rhizosphere of seedlings and mature trees of big-leaf mahogany growing in its natural habitat, a tropical rain forest in Los Tuxtlas, Veracruz, Mexico. Soil samples from a 20-cm depth were taken from the rhizosphere of big-leaf mahogany seedlings and mature trees. Additionally, spores from the rhizosphere soil were propagated on Sorghum vulgare, isolated and identified. The percentage of AMF colonization was also evaluated. RESULTS: Twenty-three AMF morphospecies belonging to four genera were registered: 11 corresponded toGlomus, 10 to Acaulospora, one to Gigaspora and one to Ambispora. Ambispora gerdemannii, Acaulospora spinosa, A. scrubiculata, A. foveata, Septoglomus constrictum, Claroideoglomus etunicatum, Glomus tenebrosum, Sclerocystis sinuosum, Diversispora aurantium,and Rhizophagus fasciculatus were identified to species level. We report for first time the presence of G. tenebrosum and C. etunicatum in natural areas of the humid Mexican tropics. The rhizosphere soil of the trees harbor more morphospecies than soil from seedlings (21 and 11 morphospecies, respectively). Sorghum plants inoculated with rhizosphere soil from big-leaf trees showed higher percentages of total mycorrhizal colonization, arbuscules and hyphae (P < 0.01) compared with plants inoculated with rhizosphere soil from seedlings. CONCLUSIONS: Twenty-three AMF morphospecies included in the genera Glomus, Acaulospora, Gigaspora andAmbispora were found associated with rhizosphere soil of mahogany trees growing in its natural habitat. The diversity of AMF genera and species found was around two times greater in mature trees than in seedlings. Some AMF species were only detected when trap-plants culture methods were employed, stressing the importance of this technique. This information has great potential for biotechnological application when performing reintroductions or reforestation with the tropical tree mahogany. <![CDATA[<b>Phenological synchrony between the austral thrush <i>Turdus falcklandii</i> (Passeriformes: Turdidae) and its food resources within forests and prairies in southern Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100010&lng=pt&nrm=iso&tlng=pt BACKGROUND: Frugivorous birds are phenologically linked to the fruits that they eat. When there is less fruit in seasonal environments, frugivorous birds complement their diet by eating invertebrates. The depth of the phenological link between frugivorous birds and their dietary resources has not been studied until now. The objective was to determine the possible phenological synchrony between the Austral thrush (Turdus falcklandii) and its dietary resource, fruits and annelids, found in the fragmented forests in the South of Chile. RESULTS: The numbers of thrushes, annelids, and fruits in fragments of native forest and anthropogenic grassland in Chile's Lake District were estimated annually. Spatial variation (i.e., forest and grassland) and seasonal variation (i.e., the period of greatest fruit growth and least fruit growth) on thrushes, annelids, and fruits were analyzed with a nonparametric Scheirer-Ray-Hare extension for the Kruskal-Wallis test. The graphic representation of the seasonal variation of thrushes, annelids, and fruits was carried out using cubic spline routines. It was found that there are seasonal changes in the dietary resources of these birds. During the period of greatest fruit production, there was a trend towards a higher number of thrushes in the forest where there was a greater availability of ripe fruit in relation to the nearby grasslands. In the grasslands, the annelids demonstrated a trend towards greater quantities in comparison with the forest. There was a positive and significant correlation between the thrushes and the annelids and fruits, indicating phenological synchrony between this bird and its dietary resources. CONCLUSIONS: Therefore, we concluded that the thrush responded numerically and functionally to the variations in its resources. The result of our research underlines the importance of grasslands in maintaining thrush populations, with this bird acting as one of the most important seed dispersers in the temperate southern forests of Chile. <![CDATA[<b>Multidisciplinary approach to assess the water self-depuration characteristics of Suquía River (Córdoba, Argentina)</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100011&lng=pt&nrm=iso&tlng=pt BACKGROUND: We analyzed the following characteristics of water self-depuration capacity along a polluted river (Suquía River) in Argentina: (a) abundance of microbial metabolic groups, (b) cover and type of vegetation, and (c) type and concentration of soil and sediment humic substances. The objective was to establish the modifications of water self-depuration characteristics of the polluted sites in comparison to a reference site in order to provide basic data for ecological restoration programs. Five samples of riparian soil, water, and sediments were collected at a reference site and five polluted sites during low- and high-flow water periods. In each site the vegetation type and soil cover were recorded. In all samples the abundance of ammonifiers, nitrate reducers, sulfate reducers, cellulolytic microorganisms, aerobic heterotrophs, and fermenters was measured. Besides, soil and sediment organic matter and humic and fulvic acids content were analyzed. RESULTS: Our results showed that all sites differed in their water self-depuration characteristics with respect to the reference site and that these variations are due to a combination of natural and anthropic factors. The Suquía River presents a great heterogeneity of water self-depuration characteristics but it does not achieve a mitigation of the anthropogenic impact produced by Córdoba city. CONCLUSIONS: We concluded that restoration actions in lotic ecosystems should be adapted for each river sector. <![CDATA[<b>Relationships between leaf anatomy, morphology, and water use efficiency in <i>Aloe vera</i> (L) Burm f. as a function of water availability</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100012&lng=pt&nrm=iso&tlng=pt The effects of water availability were evaluated on the photosynthetic tissue anatomy in Aloe vera(L) Burm f. and its relationship with morphological, physiological parameters, and water use efficiency as a function of aerial biomass and gel production. Plants were subjected to four levels of water availability equivalent to 20% (T1), 15% (T2), 10% (T3), and 5% (T4) of the atmospheric evaporative demand. The plants exhibited anatomical, morphological, and physiological responses to the different watering treatments. The extreme treatments produced negative responses due to excess water in T1 and water deficit in T4. Treatments T2 and T3 elicited positive responses in cell characteristics and productivity. Anatomical and structural characteristics were closely linked to physiology. Increased stomata number was negatively related to leaf length, width, and thickness (r = -0.85, -0.81, and -0.59, respectively) and to biomass production (r = -0.84), and positively related to the increase of cuticle thickness (r = 0.78). Treatment T2 showed the maximum efficiency of water use for biomass production (24.6 g L-1), which was closely related to cell size (r = 0.68) and number of stomata (r = -0.70). <![CDATA[<b>Cooperation and bacterial pathogenicity</b>: <b>an approach to social evolution</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100013&lng=pt&nrm=iso&tlng=pt Kin selection could provide an explanation for social behavior in bacteria. The production of public goods such as extracellular molecules is metabolically costly for bacteria but could help them to exploit nutrients or invade a host. Some bacterial cells called social cheaters do not produce public goods; however, they take advantage of these extracellular molecules. In this review, the relationships between social behavior, cooperation, and evolution of bacterial pathogenicity are analyzed. This paper also examines the role of horizontal transfer of genes encoding for virulence factors and how the movement of mobile genetic elements would influence the pathogenicity and social relationships. Moreover, the link between ecological relationships and evolution in entomopathogenic bacteria, focusing on Bacillus thuringiensis is considered. Finally, the findings obtained with B. thuringiensis are extrapolated on Bacillus pumilus 15.1, an entomopathogenic strain whose pathogenicity is not understood yet. <![CDATA[<b>Diet of the Chilean flamingo <i>Phoenicopterus chilensis</i> (Phoenicopteriformes: Phoenicopteridae) in a coastal wetland in Chiloé, southern Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100014&lng=pt&nrm=iso&tlng=pt BACKGROUND: The geographical distribution of the Chilean flamingo (Phoenicopterus chilensis) includes the southern-central Neotropics. Despite its wide distribution, currently there is no dietary information on its southern distribution range. From June to September 2011, we quantified the diet and prey availability of the Chilean flamingo in the marine wetland of Caulín (41°48' S, 73°37' W), southern Chile. RESULTS: The prey availability related to both plankton and benthos were four species of copepods, four polychaetes, one foraminifera, and two amphipods. The diet of the Chilean flamingo was composed of foraminifera (Ammonia beccarii), copepods (Harpacticus sp.) and polychaetes. The most abundant prey items from feces of flamingos were Ammonia beccarii and Harpacticus sp. The diameter of A. beccarii consumed by flamingos ranged between 400 and 900 µm, while its width varied between 100 and 300 µm. The width of Harpacticus sp. consumed ranged between 160 and 260 µm. The similarity between flamingo diet and prey availability was 0.553. The diversity of prey organisms in the benthos was higher than that observed from plankton and feces of birds. A. beccarii was preferred over other prey consumed by flamingos. This preference is not related to the size of Harpacticus sp. but to their ability to swim and escape from flamingos. CONCLUSIONS: The dietary similarity of the Chilean flamingo versus the availability of prey in the environment (plankton and benthos) was 55%, indicating that the Chilean flamingo is a partially selective predator. <![CDATA[<b>Genetic, morphological, and chemical patterns of plant hybridization</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100015&lng=pt&nrm=iso&tlng=pt Natural hybridization is a frequent phenomenon among vascular plants. Hybridization is considered an important evolutionary force since it may lead to (1) an increase of the intraspecific genetic diversity of the participating populations, (2) the creation of new species, (3) species extinction through genetic assimilation, and (4) the generation of highly invasive genotypes. Because of the importance of plant hybridization in evolution, it is of great importance to accurately identify hybrid individuals. In this review, we give a general historical background of the study of plant hybridization. Also, we review some of the tools employed for hybrid recognition and their pattern of expression in hybrid individuals (morphological, chemical, chromosome number, and DNA fingerprinting techniques). We emphasize that even when chromosome number, morphological characters, and chemical characters are of limited use for hybrid recognition in the absence of DNA fingerprinting techniques, their exploration may give insights of the ecological performance of hybrids. This is of special importance when hybridization leads to evolutionary novelty in the form of polyploidy, transgressive character expression, or the expression of new secondary metabolites not present in the parental species. <![CDATA[<b>Density and abundance of <i>Rhea pennata garleppi</i> (Struthioniformes: Rheidae) in the Puna ecoregion of Argentina</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2014000100016&lng=pt&nrm=iso&tlng=pt BACKGROUND: Rhea pennata is classified internationally as a near-threatened species, with the subspecies R. p. garleppi being listed as endangered. FINDING: The aim of this study was to provide updated information on the density and abundance of R. p. garleppi in the southern Puna ecoregion of Argentina. Density was estimated indirectly on the basis of monthly feces counts during 2011 and 2012, using line-transect surveys. Monthly abundance was calculated by multiplying the density of each month by the area of the reserve (400 km²). Population size range was calculated considering the average of the months with the highest abundance (and density) as the upper limit and the average of the months with the lowest abundance (and density) as the lower limit. The population size of this subspecies varied between 300 individuals (±60), with a density of 0.75 individuals/km² (±0.15) during the non-breeding season, and 188 individuals (±40), with a density of 0.47 individuals/km² (±0.10), during the reproductive season. CONCLUSION: This work shows the highest density record for R. p. garleppi so far and highlights changes in population size related to life history characteristics of rheas, as well as human factors that negatively affect the survival of wild populations.