Browsing by Autor "Rodrigo Wilber Soria-Auza"

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Deterministic population growth models and conservation translocation as a management strategy for the critically endangered Blue-throated Macaw (Ara glaucogularis): A critique of Maestri et al.
(Elsevier BV, 2018) Sebastián K. Herzog; Jens Bürger; Alejandra J. Troncoso; Renzo R. Vargas; Tjalle Boorsma; Rodrigo Wilber Soria-Auza
Elevational Distribution and Conservation Biogeography of Phanaeine Dung Beetles (Coleoptera: Scarabaeinae) in Bolivia
(Public Library of Science, 2013) Sebastián K. Herzog; A. Caroli Hamel‐Leigue; Trond H. Larsen; Darren J. Mann; Rodrigo Wilber Soria-Auza; Bruce D. Gill; W. D. Edmonds; Sacha Spector
Insect macroecology and conservation biogeography studies are disproportionately scarce, especially in the Neotropics. Dung beetles are an ideal focal taxon for biodiversity research and conservation. Using distribution and body size data on the ecologically important Phanaeini, the best-known Neotropical dung beetle tribe, we determined elevational patterns of species richness, endemism, body size, and elevational range in Bolivia, specifically testing Bergmann's and Rapoport's rule. Richness of all 39 species and of 15 ecoregional endemics showed a hump-shaped pattern peaking at 400 m, but overall declined strongly with elevation up to 4000 m. The relationship between endemic and total species richness appeared to be curvilinear, providing only partial support for the null hypothesis that species-rich areas are more likely to be centers of endemism by chance alone. An elevational increase in the proportion of ecoregional endemics suggests that deterministic factors also appear to influence endemism in the Andes. When controlling for the effect of area using different species-area relationships, the statistically significant richness peak became more pronounced and shifted upslope to 750 m. Larger species did not have higher elevational mid-points, and mean body size decreased significantly with elevation, contradicting Bergmann's rule. Rapoport's rule was supported: species with higher elevational mid-points had broader elevational ranges, and mean elevational range increased significantly with elevation. The elevational decrease of phanaeine richness is in accordance with studies that demonstrated the combined influence of temperature and water availability on species diversity, but also is consistent with niche conservatism. For invertebrates, confirmation of Rapoport's and refutation of Bergmann's rule appear to be scale-invariant general patterns. Analyses of biogeographic patterns across elevational gradients can provide important insights for identifying conservation priorities. Phanaeines with narrow elevational ranges on isolated low-elevation mountains in eastern Bolivia are at greatest climate-change related extinction risk from range-shift gaps and mountaintop extinctions.
First systematic sampling approach to estimating the global population size of the Critically Endangered Blue-throated Macaw<i>Ara glaucogularis</i>
(Cambridge University Press, 2020) Sebastián K. Herzog; Oswaldo Maillard Z.; Tjalle Boorsma; GUSTAVO SÁNCHEZ-ÁVILA; Víctor Hugo García-Solíz; Anahi Cosky Paca‐Condori; MARTA VAÍLEZ DE ABAJO; Rodrigo Wilber Soria-Auza
Summary Reliable population size estimates are imperative for effective conservation and management of globally threatened birds like the ‘Critically Endangered’ Blue-throated Macaw Ara glaucogularis. Endemic to one of South America’s largest grassland floodplains, the Llanos de Moxos in northern Bolivia, the species’ global population size is uncertain. The region’s inaccessibility renders the application of traditional methods for obtaining bird population estimates impracticable or cost prohibitive. We developed a simultaneous, multilocality, double-sampling approach combined with quantitative habitat availability analyses to obtain the first rigorous population size estimate for the Blue-throated Macaw. We established 11 survey areas across its three subpopulations that were visited twice by one team in each subpopulation over a 23-day period in the 2015 dry season and obtained additional count data from two roost sites. We classified suitable habitat (palm forest islands) using Landsat 8 images and CLASlite forest monitoring software. We extrapolated the number of macaws detected (conservative estimate of the total number of macaws [CETN], highest single count [HSC]) per 100 ha of suitable habitat in each survey area to the entire area of suitable habitat in all subpopulations combined, corrected for the species’ range occupancy of 34.3%. The total number of Blue-throated Macaws detected by survey (CETN) and roost site counts was 137. Across all survey areas, the number of macaws per 100 ha of suitable habitat was 4.7 for the first and 4.4 for the second period for CETN and 3.2 and 3.4, respectively, for HSC data. Corresponding global population estimates were 426–455 (CETN) and 312–329 (HSC) individuals. Other recent research and anecdotal data support these estimates. Although it would be premature to propose downlisting the species to ‘Endangered’, our findings indicate that it has a larger population and slightly larger range than previously thought, and that the positive effects of conservation actions are now becoming apparent.
Impact of Fires on Key Biodiversity Areas (KBAs) and Priority Bird Species for Conservation in Bolivia
(Multidisciplinary Digital Publishing Institute, 2022) Oswaldo Maillard; Sebastián K. Herzog; Rodrigo Wilber Soria-Auza; Roberto Vides-Almonacid
Key Biodiversity Areas (KBAs) are sites that contribute significantly to the protection of the planet’s biodiversity. In this study, we evaluated the annual burned areas and the intensity of the fires that affected Bolivia and its 58 KBAs (23.3 million ha) over the last 20 years (2001–2020). In particular, we analyzed the impact of wildfires on the distribution of Bolivian birds at the levels of overall species richness, endemic species and threatened species (Critically Endangered, Endangered, Vulnerable). We found that at the KBA level, the cumulative area of wildfires was 21.6 million ha, while the absolute area impacted was 5.6 million ha. The KBAs most affected by the wildfires are located in the departments of Beni and Santa Cruz; mainly in the KBAs Área Natural de Manejo Integrado San Matías, Oeste del río Mamoré, Este del río Mamoré, Noel Kempff Mercado and Área Natural de Manejo Integrado Otuquis. The wildfires impacted the distribution of 54 threatened species and 15 endemic species in the KBAs. Based on the results of this study, it is a priority to communicate to Bolivian government authorities the importance of KBAs as a strategy for the conservation of the country’s biodiversity and the threats resulting from anthropogenic fires.
Population status of Andean Condors in central and southern Bolivia
(Association of Field Ornithologists, 2015) Diego Méndez; Rodrigo Wilber Soria-Auza; F. Hernán Vargas; Sebastián K. Herzog
Andean Condors (Vultur gryphus) are a Near Threatened species that was formerly distributed along the entire length of the Andes from western Venezuela to Tierra del Fuego. Populations have been severely reduced north of Peru, but several thousand Andean Condors still exist in the southern portion of their range in Argentina and Chile. Little is known, however, about the size of the Andean Condor population in the central part of their range in Peru and Bolivia. From June to September 2012, we used feeding stations to attract Andean Condors and estimate the size and structure of the population in the eastern Andes of central and southern Bolivia. We estimated a minimum population of 253 condors, an adult male-to-female ratio of 1:0.6, an immature male-to-female ratio of 1:0.9, and an adult-to-immature ratio of 1:1.1. At our five survey areas, estimated abundance ranged from 15 to 100 condors per area. Males outnumbered females in three areas and the opposite was true in two areas. Our estimated adult-to-immature ratio, overall and in each area, suggests that the populations could be reproducing at a high rate. As previously observed in other Andean Condor populations, skewed sex ratios could be associated with differences between sexes and age classes in habitat selection. Although our results suggest that Bolivian populations of Andean Condors are still reasonably large, population monitoring is urgently needed, including use of feeding stations throughout the entire Bolivian range of the species and intensive searches for roosting and nesting sites. El estado de la población de cóndores andinos en los Andes del centro y el sur de Bolivia El cóndor andino (Vultur gryphus) es una especie casi amenazada que se distribuye a lo largo de los Andes desde el oeste de Venezuela hasta Tierra del Fuego. Las poblaciones han sido severamente reducidas al norte de Perú, pero varios miles de cóndores andinos todavía existen en la porción sur de su área de distribución en Argentina y Chile. Sin embargo, se conoce poco sobreel tamaño de las poblaciones de cóndor andino en la parte central de su distribución en Perú y Bolivia. Se utilizaron estaciones de alimentación para estimar el tamaño y la estructura de la población de cóndor andino en los Andes orientales del centro y sur de Bolivia. Se estimó una población mínima de 253 cóndores andinos, la proporción de entre machos y hembras adultos fue 1: 0.6, la proporción entre machos y hembras inmaduros fue 1: 0.9, y la proporción entre adultos e inmaduros fue 1:1.1. En nuestras cinco áreas de estudio, la abundancia estimada varió de 15 a 100 cóndores por área. En tres áreas los machos fueron más numerosos que las hembras, en cambio se observó lo contrario en las otras dos áreas. La proporción estimada entre adultos y jóvenes, en general y en cada área, sugiere que las poblaciones podrían tener una alta tasa de reproducción. En otras poblaciones del cóndor andino se observó que las proporciones desiguales entre sexos podrían estar asociadas con diferencias en la selección de hábitat en función al sexo y edad de los cóndores. Aunque nuestros resultados sugieren que las poblaciones de cóndor andino en Bolivia siguen siendo razonablemente grandes, es necesario continuar con su monitoreo, extendiendo el uso de estaciones de alimentación al resto del país, y de la misma forma realizar búsquedas sistemáticas de dormideros y sitios de anidamiento.
Satellite Telemetry of Blue-Throated Macaws in Barba Azul Nature Reserve (Beni, Bolivia) Reveals Likely Breeding Areas
(Multidisciplinary Digital Publishing Institute, 2021) L. Davenport; Tjalle Boorsma; Lucas A. Carrara; Paulo de Tarso Zuquim Antas; Luciene Carrara Paula Faria; Donald J. Brightsmith; Sebastián K. Herzog; Rodrigo Wilber Soria-Auza; A. Bennett Hennessey
The Blue-throated Macaw (Ara glaucogularis) is a Critically Endangered species endemic to the Llanos de Moxos ecosystem of Beni, Bolivia. To aid conservation of the northwestern population that utilizes the Barba Azul Nature Reserve during the non-breeding season, we set out to learn the sites where these birds breed using satellite telemetry. We describe preliminary tests conducted on captive birds (at Loro Parque Foundation, Tenerife, Spain) that resulted in choosing Geotrak Parrot Collars, a metal, battery-operated unit that provides data through the Argos satellite system. In September 2019, we tagged three birds in Barba Azul with Geotrak collars, and received migration data for two birds, until battery depletion in November and December 2019. Our two migrant birds were tracked leaving Barba Azul on the same date (27 September), but departed in divergent directions (approximately 90 degrees in separation). They settled in two sites approximately 50–100 km from Barba Azul. Some details of the work are restricted out of conservation concern as the species still faces poaching pressures. Knowing their likely breeding grounds, reserve managers conducted site visits to where the birds were tracked, resulting in the discovery of breeding birds, although no birds still carrying a transmitter were seen then. A single individual still carrying its collar was spotted 13 August 2021 at Barba Azul. The work suggests that the Blue-throated Macaws of Barba Azul use breeding sites that are scattered across the Llanos de Moxos region, although within the recognized boundaries of the northwestern subpopulation. We conclude that the use of satellite collars is a feasible option for research with the species and could provide further conservation insights.