Abstract:

El visón Americano es una especie introducida con una amplia distribución en Patagonia y por su comportamiento de forrajeo es el carnívoro invasor con el mayor potencial para afectar a la biodiversidad en la región. La información disponible acerca de la presencia/ ausencia del visón en la región y de estimaciones poblacionales es muy escasa aun cuando esto es vital para la planificación de acciones de manejo. En este trabajo integramos la información disponible acerca de la presencia del visón hasta la fecha y evaluamos su presencia en sitios donde hay vacíos de información, basándonos en la ubicación de los puntos de liberación de individuos, distribución confirmada y estimaciones de la capacidad de dispersión. Proponemos una Herramienta de Priorización de Áreas (HPA) para definir sitios prioritarios para el manejo, superponiendo mapas de distribución de la especie, de hábitat adecuado y de áreas de importancia para la conservación de la biodiversidad. Entre las áreas prioritarias, seleccionamos tres y sugerimos un Protocolo de Tareas de Erradicación (PTE) como estrategia de manejo del visón americano, basado en experiencias de erradicación Europeas exitosas. Finalmente, estimamos costos relativos asociados a la implementación de tal PTE en cada una de las áreas seleccionadas. Presentamos este trabajo como una herramienta aplicada, enfocada en mostrar una forma simplificada para afrontar el problema de las especies invasoras en Patagonia y su manejo.

The American mink is a widespread invasive carnivore in Patagonia, and due to its foraging behavior that allows it to exploit a wide variety of prey, it is the exotic carnivore with the highest potential impact on the region’s biodiversity. Available regional information on mink presence/absence, as well as abundance estimations, is scarce even though it is vital to plan management actions. Here, we integrate the confirmed distribution of mink in Patagonia with its potential presence for areas where information is lacking, based on the location of animal releases and estimated dispersal rates. We propose an Area Prioritization Tool (APT) for invasive species management by overlapping habitat suitability, current known range, colonization fronts and areas deemed important for biodiversity conservation. Among the prioritized areas, we selected three and suggested a Protocol for Eradication Tasks (PET), based on successful mink eradication experiences in Europe. Finally, we estimated the relative costs associated with the PET’s implementation in each area. We present this work as a systematic, applied tool to show a feasible way to face the invasive species problems in Patagonia and their management.

Abstract:

The critically endangered hooded grebe Podiceps gallardoi has suffered a population reduction of 80% in the last 25 years. Although climatic conditions have been mentioned as important causes of this decline, invasive species are also playing a main role. Hooded grebes have the lowest recruitment rate within the Podicepodiformes, but this is compensated by high adult survival. Considering these life history traits and threats, we designed the "colony guardian programme", which ed to protect nesting grebes. We describe the methods used to reduce the negative impacts of American mink and kelp gull on breeding colonies of grebes in central-western Santa Cruz Province, Argentina. Since the breeding season of 2011-2012, 10 colonies were protected using a total of 755 fieldwork days. Colonies guarded throughout the breeding season had higher recruitment (0.64 juveniles/breeding pair) than colonies with no or little protection (0.39 juveniles/breeding pair).

Author affiliation: Roesler, Carlos Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología y Comportamiento Animal; Argentina

Author affiliation: Fasola, Laura. Administración de Parques Nacionales. Delegación Regional Patagonia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Casañas, Hernán. Aves Argentinas, Asociación Ornitológica del Plata; Argentina

Author affiliation: Hernández, Pablo Martín. Aves Argentinas, Asociación Ornitológica del Plata; Argentina

Author affiliation: de Miguel, Andrés. Aves Argentinas, Asociación Ornitológica del Plata; Argentina

Author affiliation: Giusti, Maria Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Aves Argentinas, Asociación Ornitológica del Plata; Argentina

Author affiliation: Reboreda, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

Abstract:

Knowledge of food habits of invasive species is necessary to predict invasion success and potential interactions in the invaded community. The Asiatic red-bellied squirrel Callosciurus erythraeus has been introduced in Asia, Europe and South America. We studied feeding habits of red-bellied squirrels in Argentina in two sites 600 km apart where wild populations have become established. We used both faecal microhistological analysis and behavioural records to describe diet composition and feeding habits. We also analysed diet selection and the potential role of the squirrels as seed disperser. Squirrels consumed items from 35 species of exotic trees and shrubs and one native tree species; fruits and seeds represented the bulk of the diet in all seasons (faeces analysis: >44%; behavioural observations: >38%). Squirrels also consumed epiphytic and climbing plants, ferns, invertebrates, fungi, lichens, mosses and bird eggs. Diet composition varied throughout the year according to food availability. We did not find evidence of endozoochoric dispersal but we observed squirrels carrying and dropping nuts and acorns during transport. The consumption of a wide range of food items and species, the ability to modify the diet according to food availability, and the capacity to hoard food indicate that feeding habits of red-bellied squirrels favour their invasive potential.

Author affiliation: Zarco, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentina

Author affiliation: Benitez, Verónica Victoria. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Funes, G.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Author affiliation: Guichon, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Provincia del Neuquén. Subsecretaría de Producción y Recursos Naturales. Centro de Ecología Aplicada del Neuquén; Argentina

Abstract:

El visón Americano es una especie introducida con una amplia distribución en Patagonia y por su comportamiento de forrajeo es el carnívoro invasor con el mayor potencial para afectar a la biodiversidad en la región. La información disponible acerca de la presencia/ ausencia del visón en la región y de estimaciones poblacionales es muy escasa aun cuando esto es vital para la planificación de acciones de manejo. En este trabajo integramos la información disponible acerca de la presencia del visón hasta la fecha y evaluamos su presencia en sitios donde hay vacíos de información, basándonos en la ubicación de los puntos de liberación de individuos, distribución confirmada y estimaciones de la capacidad de dispersión. Proponemos una Herramienta de Priorización de Áreas (HPA) para definir sitios prioritarios para el manejo, superponiendo mapas de distribución de la especie, de hábitat adecuado y de áreas de importancia para la conservación de la biodiversidad. Entre las áreas prioritarias, seleccionamos tres y sugerimos un Protocolo de Tareas de Erradicación (PTE) como estrategia de manejo del visón americano, basado en experiencias de erradicación Europeas exitosas. Finalmente, estimamos costos relativos asociados a la implementación de tal PTE en cada una de las áreas seleccionadas. Presentamos este trabajo como una herramienta aplicada, enfocada en mostrar una forma simplificada para afrontar el problema de las especies invasoras en Patagonia y su manejo.

The American mink is a widespread invasive carnivore in Patagonia, and due to its foraging behavior that allows it to exploit a wide variety of prey, it is the exotic carnivore with the highest potential impact on the region's biodiversity. Available regional information on mink presence/absence, as well as abundance estimations, is scarce even though it is vital to plan management actions. Here, we integrate the confirmed distribution of mink in Patagonia with its potential presence for areas where information is lacking, based on the location of animal releases and estimated dispersal rates. We propose an Area Prioritization Tool (APT) for invasive species management by overlapping habitat suitability, current known range, colonization fronts and areas deemed important for biodiversity conservation. Among the prioritized areas, we selected three and suggested a Protocol for Eradication Tasks (PET), based on successful mink eradication experiences in Europe. Finally, we estimated the relative costs associated with the PET's implementation in each area. We present this work as a systematic, applied tool to show a feasible way to face the invasive species problems in Patagonia and their management.

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Valenzuela, Alejandro Eduardo Jorge. Administración de Parques Nacionales. Delegación Regional Patagonia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Abstract:

We describe nest-site characteristics and studied breeding habitat use of Kelp geese (Chloephaga hybrida) and Flightless Steamer ducks (Tachyeres pteneres) along 137km of coastline on the northern shore of the Beagle Channel, Argentina, and 87 km of island coastline. Also, we examined the importance of vegetation cover, predation and tourism on the distribution of nests among islands. We found all nests only on islands and islets. Nesting sites for both species were strongly associated with higher proportions of high vegetation cover (shrubs), and for Kelp geese they were also associated to the absence of terrestrial predators. Tourist presence on islands was not associated to the presence of nest for neither species. The northern coasts of the Beagle Channel and the islands and islets along the channel have similar habitat types. However, the islands and islets are relatively inaccessible to mammalian terrestrial predators compared to the coast of the channel were terrestrial predators are frequently recorded. Therefore, islands and islets seem to provide a relatively safe nesting habitat for Kelp geese and Flightless Steamer ducks by offering refuge mainly from ground predators. Additionally, habitat changes caused by increased human disturbance along the northern shore of the Beagle Channel may also explain the presence of nests only on islands and islets, though further studies are needed to assess these effects. This study provides new information on the breeding habitat and nesting sites of Flightless Steamer ducks and Kelp geese in the Beagle Channel, which in the future may contribute to the identification of priority breeding sites, and habitats and habitat features to protect. Also, it highlights the importance of islands and islets of the Beagle Channel as a safe breeding refuge for these two ground nesting seabirds.

Author affiliation: Liljesthrom, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Schiavini, Adrian Carlos Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Saenz Samaniego, Ricardo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Raya Rey, Andrea Nélida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Abstract:

Understanding processes and impacts of biological invasions is fundamental for ecology and management. Recent reviews summarized the mechanisms by which invasive species alter entire ecosystems, but quantitative assessments of these mechanisms are lacking for actual assemblages to determine their relative importance, frequency and patterns. We updated information on introduced vertebrates in the Tierra del Fuego Archipelago (TDF) via an exhaustive literature review and new data to evaluate ecosystem impact mechanisms and provide management recommendations. To date, 24 exotic vertebrates have naturalized in TDF, outnumbering natives nearly 2:1, with the North American beaver (Castor canadensis) and muskrat (Ondatra zibethica) being the most widely distributed species and also impacting the ecosystem through the greatest number of mechanisms. Introduced vertebrates occupied most parts of the archipelago with human-inhabited islands having greater taxa richness. All exotics potentially altered ecosystems by one or more mechanisms: 100% food webs, 92% invasional meltdown, 42% habitat modification, 38% disease or parasite transmission, 21% soil property and disturbance regime changes. Impact to habitat structure was the main clustering criterion for this assemblage. Within the species that physically alter habitats, we found two sub-groups: 1) large herbivores and 2) ?others? including beavers and muskrats. Species that did not alter habitat were divided further into those with predatory trophic effects (carnivorous mammals and trout, sub-group 4) and the rest with assorted impacts (sub-group 3). By establishing high quality information on archipelago-wide assemblage, distribution, impacts and mechanisms for exotic vertebrates, we recommend, based on ecological criteria, prioritizing the management of sub-group 2. A secondary priority might be given to the carnivores in sub-group 4, while species in sub-groups 1 and 3 are less urgent. As the first systematic survey of introduced fauna on an archipelago-scale, we identified knowledge gaps, such as population abundance and dynamics for specific species, which are needed to orient future work, but the notable progress made to date is highlighted.

Author affiliation: Valenzuela, Alejandro Eduardo Jorge. Administración de Parques Nacionales Argentinos; Argentina

Author affiliation: Anderson, Christopher Brian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de Tierra del Fuego; Argentina. Omora Sub-Antarctic Research Alliance; Estados Unidos

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Cabello, José Luís. Patagonia Wildlife Ltda.; Argentina

Abstract:

A combination of infrared cameras and plasticine eggs were used to identify potential nest predators of Flightless Steamer-Ducks (Tachyeres pteneres) and Flying Steamer-Ducks (T. patachonicus) and to evaluate the relative efficacy of these methods for identifying predators. Cameras were set up at 31 artificial nests with plasticine eggs and at four Flightless and two Flying steamer-duck nests. Two avian predators, Chimango Caracara (Milvago chimango) and Southern Crested Caracara (Caracara plancus), and two mammalian predators, Fuegian Culpeo fox (Pseudalopex culpaeus lycoides) and American mink (Neovison vison), were identified as depredating artificial nests from photos. Active Flightless and Flying steamer-duck nests were found only on islets, and from the photos the Chimango and Southern Crested caracaras were identified as nest predators. Mammalian predators were not photographed on islets (neither on artificial nor natural nests). Though the potential predator community at Lapataia Bay was small, there were considerable similarities in physical evidence and marks left at nests, especially within avian predators. Also, depredated nests were sometimes revisited by other predators and these multi-predator visits sometimes caused changes to the appearance of the depredated nest following departure of the initial predator. The cameras provided an objective method for definitive identification of nest predators.

Author affiliation: Liljesthrom, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Valenzuela, Alejandro Eduardo Jorge. Administración de Parques Nacionales. Delegación Regional Patagonia; Argentina

Author affiliation: Raya Rey, Andrea Nélida. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Schiavini, Adrian Carlos Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Abstract:

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.

Author affiliation: Pietrek, Alejandro G.. University Of Duke; Estados Unidos

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Abstract:

Background: American mink forage on land and in water, with aquatic prey often constituting a large proportion of their diet. Their long, thin body shape and relatively poor insulation make them vulnerable to heat loss, particularly in water, yet some individuals dive over 100 times a day. At the level of individual dives, previous research found no difference in dive depth or duration, or the total number of dives per day between seasons, but mink did appear to make more dives per active hour in winter than in summer. There was also no difference in the depth or duration of individual dives between the sexes, but there was some evidence that females made more dives per day than males. However, because individual mink dives tend to be extremely short in duration, persistence (quantified as the number of consecutive dives performed) may be a more appropriate metric with which to compare diving behaviour under different scenarios. Results: Mink performed up to 28 consecutive dives, and dived continually for up to 36 min. Periods of more loosely aggregated diving (termed ‘aquatic activity sessions’) comprised up to 80 dives, carried out over up to 162.8 min. Contrary to our predictions, persistence was inversely proportional to body weight, with small animals more persistent than large ones, and (for females, but not for males) increased with decreasing temperature. For both sexes, persistence was greater during the day than during the night. Conclusions: The observed body weight effect may point to inter-sexual niche partitioning, since in mink the smallest animals are females and the largest are males. The results may equally point to individual specialism’s, since persistence was also highly variable among individuals. Given the energetic costs involved, the extreme persistence of some animals observed in winter suggests that the costs of occasional prolonged activity in cold water are outweighed by the energetic gains. Analysing dive persistence can provide information on an animal’s physical capabilities for performing multiple dives and may reveal how such behaviour is affected by different conditions. Further development of monitoring and biologging methodology to allow quantification of hunting success, and thus the rewards obtained under alternative scenarios, would be insightful.

Author affiliation: Bagniewska, Joanna M.. University Of Oxford; Reino Unido. University Of Reading; Reino Unido

Author affiliation: Harrington, Lauren A.. University Of Oxford; Reino Unido

Author affiliation: Hart, Tom. University Of Oxford; Reino Unido

Author affiliation: Harrington, Andrew L.. University Of Oxford; Reino Unido

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Macdonald, David W.. University Of Oxford; Reino Unido

Abstract:

The Ruddy-headed Goose Chloephaga rubidiceps has two separate and genetically distinct populations, one sedentary that inhabits the Malvinas/Falklands Islands and another migratory, which inhabits continental southern South America. New information suggests that these populations should be considered as different evolutionarily significant units. The latter population breeds in Austral Patagonia (Argentina and Chile) and overwinters in Central Argentina. It was a very common species in Austral Magellanic steppe grasslands before 1931, when it was declared an agricultural pest by the Argentinian government, together with other sheldgeese species. Since then, the continental Ruddy-headed Goose population has declined becoming one of the scarcest species in Austral Magellanic steppe. Nowadays, its population is categorised as critically endangered in Argentina and endangered in Chile. We present data from six road censuses conducted in the breeding areas of Santa Cruz and Tierra del Fuego provinces, Argentina, during 2013-2014 and 2014-2015 (>4600 km, 70 days) and review population trends of the Ruddy-headed Goose since the early 1900s. We counted a maximum of 19 individuals in Santa Cruz and 49 in Tierra del Fuego throughout the breeding season. A literature review indicates that during the last 40 years the size of continental population of Ruddy-headed Goose has been < 800 individuals, approximately 10% of the estimated population in the 1900s. This decline matches the period following the application of control techniques and the introduction of exotic predator species in the breeding grounds of Tierra del Fuego. We review and discuss formerly proposed conservation actions that may have a positive and rapid effect on sheldgoose numbers recovery. We suggest that the continental population of Ruddy-headed Goose should on a precautionary basis be treated as a critically endangered population until genetic studies determine whether we are in the presence of a new 'Critically Endangered' species.

Author affiliation: Cossa, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

Author affiliation: Fasola, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Author affiliation: Roesler, Carlos Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina

Author affiliation: Reboreda, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina