Browsing by Author "Rau, Jaime R."

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    COMPOSITION, DIVERSITY AND SIZE OF DIATOMS CONSUMED BY THE ANDEAN FLAMINGO (PHOENICOPARRUS ANDINUS) IN SALAR DE PUNTA NEGRA, ANTOFAGASTA REGION, NORTHERN CHILE
    (2012) Tobar, Claudio; Rau, Jaime R.; Iriarte, Agustin; Villalobos, Rodrigo; Lagos, Nicolas; Cursach, Jaime; Diaz, Carolina; Fuentes, Norka; Gantz, Alberto
    In April 2009, at the Salar de Punta Negra (24 degrees 35'S, 68 degrees 58'W) in the Antofagasta Region of northern Chile, we quantified the composition, diversity, and size of diatoms, the only consumed prey by both adults and nestlings of Andean Flamingos (Phoenicoparrus andinus). We identified a total of 39 species, 34 in the faeces of nestlings and 25 in adult faeces. The most abundant species in both was Surirella se//a and Denticula thermal/s. The most frequent diatoms observed in the nestlings' faeces were S. se/la, D. thermalis, Pinnularia sp. and Haloroundia speciosa, whereas in the adult faeces they were Denticula thermalis, Surirella se//a, Pinnularia sp. and Haloroundia speciosa. There was no statistically significant difference in diatoms consumed by adults and nestlings. The dietary similarity between adults and nestlings was 0.644. The nestlings consumed a greater diversity of diatoms than adults. The most consumed diatom by adults (S. sea) was sized between 58 and 140 mu m, with a greater frequency for organisms between 70 and 100 mu m. The size of the diatoms consumed by nestlings was between 40 and 120 mu m with a greater frequency of organisms between 60 and 90 pm. Comparing the sizes of the consumed diatoms, we found that adults preferred individuals of greater size than nestlings. Accepted 18 June 2012.
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    Density, abundance, and activity of the chilla or grey fox (Lycalopex griseus) in Isla Grande de Tierra del Fuego, Chile
    (2024) Zurita Redón, Carlos Nicolás Felipe; Oporto, Javier; Valverde, Ignacio; Bernales, Borja; Soto, Nicolás; Rau, Jaime R.; Jaksic Andrade, Fabián
    Background: The chilla or grey fox (Lycalopex griseus) is a native species from continental Chile and neighboring areas of Argentina. It was introduced to Isla Grande de Tierra del Fuego in 1951 and began to increase its abundance, to the chagrin of local sheep ranchers. Since 1998, its hunting has been authorized. Here we update information on the density, abundance, and activity of this fox in the Chilean sector of Tierra del Fuego Island, to evaluate its population trend since the last census conducted by the Servicio Agrícola y Ganadero (SAG) in 2007. Methods and results: We carried out two fox censuses on a 941-km transect on public roads, divided into eight routes, from October to November (spring) of 2021 and 2022, following the same design used by SAG for the fox assessments carried out from 1999 to 2007. We report a reduction of>50% in the density and abundance of chilla foxes with respect to the 2007 estimate, which could be attributed to the interference by free-ranging dogs (Canis lupus familiaris), through restricting the use of space by the fox, while transmitting diseases and parasites, and to human hunting pressure and vehicle collisions. Discussion: The chilla fox decline highlights the need for an in-depth study to determine the ecological and socioeconomic impact of this exotic species on the ecosystems of Tierra del Fuego Island and the desirability of its management, if needed.
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    EVIDENCE OF HIGH CONSUMPTION OF WASTE BY THE ANDEAN CONDOR (VULTUR GRYPHUS) IN AN ANTHROPIZED ENVIRONMENT OF CHILE
    (2019) Pavez, Eduardo F.; Duclos, Melanie; Rau, Jaime R.; Sade, Soraya; Jaksic, Fabian M.
    Anthropogenic food subsidies and waste disposals have become a new food resource for wildlife, including the Andean Condor (Vultur gryphus), a situation that implies benefits and health risks. To increase understanding of Andean Condor feeding habits in the most anthropized area in Chile, we analyzed 280 pellets collected during 2016 from one roost in the Metropolitan Region, central Chile. We identified the main diagnostic elements microscopically and expressed them as percentage of occurrence (percentage of each item in relation to all pellets). We found 12 prey categories (including mammals, birds, and plant material) and 9 waste categories. Condors fed mainly on mammals (99%); livestock was their main feeding source (52%), followed by native (22%) and exotic wild species (19%). Birds were detected less frequently (8%). We found a high occurrence of waste (31%), of which plastic remains were the main item (27%). According to our results, landfills serve as a complementary food source for condors, probably a low-quality but easily accessible, and which exposes them to a variety of health and mortality risks. Despite the fact that Andean Condors can reach distant places in foraging flights to find food resources, a high proportion of the population is attracted to rubbish dumps and landfills. Despite the spatio-temporal limitations of our results, this is the first record that describes and quantifies a high presence of waste as a component of the Andean Condor diet. We recommend a more comprehensive study to assess their feeding habits and habitat preferences in a broader spatio-temporal context, and to determine the possible impact of the use of waste disposals on Andean Condor populations.
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    Fire Severity Causes Temporal Changes in Ground-Dwelling Arthropod Assemblages of Patagonian Araucaria-Nothofagus Forests
    (2022) Zuniga, Alfredo H.; Rau, Jaime R.; Fierro, Andres; Vergara, Pablo M.; Encina-Montoya, Francisco; Fuentes-Ramirez, Andres; Jaksic, Fabian M.
    Fire is one of the main drivers of anthropogenic disturbances in temperate forest ecosystems worldwide, with multiple effects spread across ecological networks. Nevertheless, the biodiversity effects of fire are poorly known for species-diverse groups such as arthropods. In this research, we used a burn gradient generated two and three years after a large fire event to assess how different levels of fire severity affect arthropod diversity in the forest with the main forest forming long-living tree species Araucaria araucana, in southern Chile. The species richness and abundance of arthropods among trophic guilds was estimated annually in four fire-severity levels. We found that arthropods responded differently to fire severity levels, depending on their trophic guilds and years after fire (two and three years after fire). During the second year after fire, zoophages, phytophages, and parasitoids were more diverse in areas with high fire severity within the second year after fire, as compared to those in areas with low severity or unburned stands. In the third year after fire, a change in this trend was observed, where the abundance of all groups dropped significantly, with positive changes in the diversity in zoophages, phytophages, polyphages and saprophages, which is more noticeable in sites with high severity. These results indicate that annual variation in environmental conditions triggers bottom-up cascading effects for arthropods. Forests stands severely impacted by fires support highly fluctuating and possibly unstable arthropod assemblages. Hence, restoration efforts should be focused on recovering microhabitat conditions in these stands to allow the persistence of arthropods.
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    Population status of the Peruvian Pelican (Pelecanus thagus) in Chile: initial survey
    (NEOTROPICAL ORNITHOLOGICAL SOC, USGS PATUXENT WILDLIFE RESEARCH CTR, 2018) Cursach, Jaime A.; Rau, Jaime R.; Gelcich, Stefan; Rodriguez Maulen, Juan
    The Peruvian Pelican (Pelecanus thagus) is an endemic seabird of the Humboldt Current System in South America, inhabiting the Pacific coast from the south of Ecuador, Peru to the south of Chile. In Peru it is classified as an Endangered species, while globally it is considered Near Threatened. Although more than 50% of the habitat used by the Peruvian Pelican occurs on the coast of Chile, its population trends and conservation status remain unknown in this country. For this reason, the objective of the present work was to diagnose the population situation of the Peruvian Pelican in Chile, through the analysis of databases and perceptions of local ornithologists. Between the years 2010 and 2015 the abundance of Peruvian Pelican in Chile decreased significantly in the central zone of the country. There is seasonality in its presence, with greater abundances during the winter season. The perception of local ornithologists indicated a population increase towards the south of the country. Along the Chilean coast, 24 nesting sites of the Peruvian Pelican have been described, of which 29.1% are located inside of protected areas. Finally, we identify future research questions, suggest the need to apply a meta-population approach, and establish international collaboration frameworks for the study and conservation of the Peruvian Pelican.
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    World-level ecologists in Chile : oldtimers, newcomers, and the bypassed
    (2022) Rau, Jaime R.; Jaksic Andrade, Fabián
    Background: A team of 3 scientometrists led by John Ioannidis published in 2020 an extensive and updated database (ca. 6.9 million researchers in 22 disciplines and 176 sub-disciplines), ordering them according to a composite bibliometric index that measures their whole trajectory (career-long) impact and their annual impact at year 2019. They reported the top 100,000 scientists (1.45% across all disciplinary felds) or the top 2% of each subfeld discipline, thus publishing the ranking of ca. 150,000 researchers worldwide. Methods and fndings: We fltered that information for the disciplinary and sub-disciplinary areas corresponding to Ecology and identifed a total of 14 ecologists with residence in Chile that appear in either of those two worldwide rankings. We report their measured productivity as both whole trajectory (career-long) and as annual impact at year 2019. We attribute their high registered productivity to their training at the doctoral level in prestigious foreign universities, their academic positions in internationally recognized Chilean universities, and their participation in statefunded research centers of scientifc excellence. Exceptions to the rule are presented. Conclusions: The 14 ecologists identifed with the scientometric algorithm proposed by Ioannidis and coworkers include, but are not restricted, to the most cited ecologists in Chile. We put forth possible reasons for some puzzling omissions from these rankings.