Origen e historia de la introducción del castor en América del Sur

The introduction of the North American beaver (Castor canadensis) to Tierra del Fuego is a widely known example of a successful biological invasion. However, the origin and history of this introduction bears closer scrutiny. Using historical documentation we provide evidence that beaver introduction occurred as a single release event of 20 beavers from northern Manitoba, Canada. This not only clarifies the origin of the invasion, but also suggests that the beaver population of Patagonia descends from a smaller number of individuals than previously assumed.La introducción del castor norteamericano (Castor canadensis) en Tierra del Fuego es un ejemplo ampliamente conocido de una invasión biológica exitosa. Sin embargo, el origen y la historia de su introducción merecen mayor análisis. Usando documentación histórica, presentamos evidencia de que la introducción del castor se originó en un único evento de liberación de 20 castores que arribaron desde el norte de Manitoba en Canadá. Esto no solo aclara el origen de la invasión, sino que sugiere que la población de castores en Patagonia deriva de un número de individuos menor que el que se asumía hasta el momento.Fil: Pietrek, Alejandro G.. University Of Duke; Estados UnidosFil: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Habitat occupancy of the threatened Diademed Plover (Phegornis mitchellii) is not affected by llama grazing or peatland size, but declines with peatland humidity

Fil: Pietrek, Alejandro G. University of California Santa Cruz. Ecology and Evolutionary Biology Department. Santa Cruz, CA; United States of America.Fil: Pietrek, Alejandro G. Universidad Nacional de Salta; Argentina.Fil: Pietrek, Alejandro G. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Bio y Geociencias del NOA; Argentina.Fil: Cockle, Kristina L. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología Subtropical, Puerto Iguazú, Misiones; Argentina.Fil: Izquierdo, Andrea E. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Izquierdo, Andrea E. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Berrios, Viviana S. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina.Fil: Berrios, Viviana S. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Lyon, Bruce E. University of California Santa Cruz. Ecology and Evolutionary Biology Department. Santa Cruz, CA; United States of America.Fil: Lyon, Bruce E. Universidad Nacional de Salta; Argentina.Fil: Lyon, Bruce E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Bio y Geociencias del NOA; Argentina.Many habitat-specialist organisms occur in distinct, patchy habitat, yet do not occupy all patches, and an important question is why apparently suitable habitat remains unoccupied. We examined factors influencing patch occupancy in near-threatened, little-known Diademed Plovers (Phegornis mitchellii), arguably the bird most specialized to life in High Andean peatlands. Andean peatlands are well-suited to occupancy modelling because they are discrete patches of humid habitat within a matrix of high-altitude steppe. We hypothesized that Diademed Plovers occupy preferably larger and more humid peatlands, and avoid peatlands used for grazing by llamas and vicuñas, which may trample vegetation and nests. From December 2021 to February 2022 (breeding season), we conducted plover occupancy surveys (2–4) on 40 peatlands at Lagunas de Vilama, a landscape of arid steppe and wetlands above 4,500 m in NW Argentina. We measured peatland size, grazing pressure, topographic and remotely-sensed variables that correlate with humidity, and incorporated these as covariates in occupancy models. Occupancy models showed that more than 50% of the studied peatlands were used by Diademed Plovers and most showed signs of reproduction, highlighting the importance of the Vilama Wetlands for Diademed Plover conservation. Within peatlands, Diademed Plovers were most often associated with headwaters. The top ranked occupancy model included constant detection, random spatial effects, and a single occupancy covariate: mean NDWI (Normalized Difference Water Index, an index correlated with water content and humidity) over the previous three years. Contrary to our prediction, Diademed Plovers preferred less water-saturated peatlands (lower NDWI), possibly to avoid nest flooding. This may be especially important in wet years, like the year when we conducted our surveys. Neither peatland size nor grazing by llamas and vicuñas affected peatland use by Diademed Plovers, suggesting that llama grazing at current levels may be compatible with plover conservation. For organisms that specialize on humid habitats, such as peatlands, factors affecting occupancy may vary temporally with variation in climate, and we recommend follow-up surveys across multi-year timescales to untangle the impact of climate on animals’ use of humid habitats.info:eu-repo/semantics/publishedVersionFil: Pietrek, Alejandro G. University of California Santa Cruz. Ecology and Evolutionary Biology Department. Santa Cruz, CA; United States of America.Fil: Pietrek, Alejandro G. Universidad Nacional de Salta; Argentina.Fil: Pietrek, Alejandro G. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Bio y Geociencias del NOA; Argentina.Fil: Cockle, Kristina L. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología Subtropical, Puerto Iguazú, Misiones; Argentina.Fil: Izquierdo, Andrea E. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Izquierdo, Andrea E. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Berrios, Viviana S. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina.Fil: Berrios, Viviana S. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Lyon, Bruce E. University of California Santa Cruz. Ecology and Evolutionary Biology Department. Santa Cruz, CA; United States of America.Fil: Lyon, Bruce E. Universidad Nacional de Salta; Argentina.Fil: Lyon, Bruce E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Bio y Geociencias del NOA; Argentina

Why Do Beavers Leave Home? Lodge Abandonment in an Invasive Population in Patagonia

Research Highlights: Lodge abandonment by beavers is apparently a common phenomenon in Patagonia, but it is still poorly understood and we ignore what drives it. In relatively slow growth Nothofagus forests, resource depletion can impact abandonment while water availability may be a major driver in the semiarid steppe. Background and Objectives: North American beaver (Castor canadensis) was introduced in 1946 on the island of Tierra del Fuego (TDF) in southern Argentina. Since then, beavers have become a major disturbance affecting not only forest but also treeless steppe landscapes. Our goal was to determine the factors affecting lodge abandonment by beavers in two habitats of TDF: forest and steppe. Materials and Methods: A total of 47 lodges were surveyed between February and March from 2012 to 2014 in both habitat types, 22 in the forest and 25 in the steppe. To explain factors involved in lodge abandonment by beavers, we measured the following variables: water level variation, stream gradient, vegetation cover adjacent to shore and forest structure. Results: We recorded 24 abandonments events, with a similar proportion of lodges abandoned in both habitats. Our results revealed that lodge abandonment was mostly linked to water level fluctuations irrespective of habitat type. The water level at the entrances of the lodge generally decreased in abandoned lodges. Variables that characterize understory cover had some influence on lodge abandonment in the forest, and no effect in the steppe. Conclusions: Water level variation was associated with lodge abandonment in both habitats, and we found some evidence of resource depletion in the forest. However, we caution that changes in water level may be not only due to extrinsic factors but rather to beaver's own activities or to a decay in pond maintenance following abandonment

Disruption of an ant-plant mutualism shapes interactions between lions and their primary prey

Mutualisms often define ecosystems, but they are susceptible to human activities. Combining experiments, animal tracking, and mortality investigations, we show that the invasive big-headed ant (Pheidole megacephala) makes lions (Panthera leo) less effective at killing their primary prey, plains zebra (Equus quagga). Big-headed ants disrupted the mutualism between native ants (Crematogaster spp.) and the dominant whistling-thorn tree (Vachellia drepanolobium), rendering trees vulnerable to elephant (Loxodonta africana) browsing and resulting in landscapes with higher visibility. Although zebra kills were significantly less likely to occur in higher-visibility, invaded areas, lion numbers did not decline since the onset of the invasion, likely because of prey-switching to African buffalo (Syncerus caffer). We show that by controlling biophysical structure across landscapes, a tiny invader reconfigured predator-prey dynamics among iconic species

Neotropical ornithology: Reckoning with historical assumptions, removing systemic barriers, and reimagining the future

A major barrier to advancing ornithology is the systemic exclusion of professionals from the Global South. A recent special feature, Advances in Neotropical Ornithology, and a shortfalls analysis therein, unintentionally followed a long-standing pattern of highlighting individuals, knowledge, and views from the Global North, while largely omitting the perspectives of people based within the Neotropics. Here, we review current strengths and opportunities in the practice of Neotropical ornithology. Further, we discuss problems with assessing the state of Neotropical ornithology through a northern lens, including discovery narratives, incomplete (and biased) understanding of history and advances, and the promotion of agendas that, while currently popular in the north, may not fit the needs and realities of Neotropical research. We argue that future advances in Neotropical ornithology will critically depend on identifying and addressing the systemic barriers that hold back ornithologists who live and work in the Neotropics: unreliable and limited funding, exclusion from international research leadership, restricted dissemination of knowledge (e.g., through language hegemony and citation bias), and logistical barriers. Moving forward, we must examine and acknowledge the colonial roots of our discipline, and explicitly promote anti-colonial agendas for research, training, and conservation. We invite our colleagues within and beyond the Neotropics to join us in creating new models of governance that establish research priorities with vigorous participation of ornithologists and communities within the Neotropical region. To include a diversity of perspectives, we must systemically address discrimination and bias rooted in the socioeconomic class system, anti-Blackness, anti-Brownness, anti-Indigeneity, misogyny, homophobia, tokenism, and ableism. Instead of seeking individual excellence and rewarding top-down leadership, institutions in the North and South can promote collective leadership. In adopting these approaches, we, ornithologists, will join a community of researchers across academia building new paradigms that can reconcile our relationships and transform science. Spanish and Portuguese translations are available in the Supplementary Material.• Research conducted by ornithologists living and working in Latin America and the Caribbean has been historically and systemically excluded from global scientific paradigms, ultimately holding back ornithology as a discipline.• To avoid replicating systems of exclusion in ornithology, authors, editors, reviewers, journals, scientific societies, and research institutions need to interrupt long-held assumptions, improve research practices, and change policies around funding and publication.• To advance Neotropical ornithology and conserve birds across the Americas, institutions should invest directly in basic field biology research, reward collective leadership, and strengthen funding and professional development opportunities for people affected by current research policies.Peer reviewe