Seasonal variation in the diet of Lontra longicaudis in the Paraná River basin, Argentina

We studied the Neotropical otter ( Lontra longicaudis ) seasonal diet variations in the middle Paran á River valley, in central-northern Argentina, at the southern limit of its global range. We recorded 745 prey items in 320 scats collected over the course of 1 year in a tributary stream of the Paran á River. Fish, crustaceans, mammals, and insects were the most important items in frequency of occurrence among items. Other items, like mollusks, birds, amphibians, and reptilians were presented in low frequency in all seasons. We recorded seasonal variation in the frequency of the principal categories items: fish, mammals, crustaceans, and insects and in reptilian that had low frequency. Although fish were the most common items consumed by the otter, other groups such as crustaceans, mammals, and insects, were also important in the diet of the Neotropical otter throughout the seasons. Mammals and insects showed a higher frequency in the Neotropical otter diet in our study than in Brazil, Mexico, and even northern Argentina. We noted a marked variation throughout the Neotropical region in the niche breadth indices among studies of Neotropical otter ’ s diet. The Shannon H ′ diversity index showed a higher value in our study than in most of previous diet analyses of this species.Fil: Vezzosi, Raúl Ignacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Eberhardt, María Ayelen Teresita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Cs.veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Ciencias Veterinarias del Litoral; Argentina. Laboratorio de Ecología de Enfermedades; ArgentinaFil: Raimondi, Vanina Belén. Universidad Nacional de Rosario. Facultad de Ciencias exactas, Ingeniería y Agrimensura. Museo "Florentino y Carlos Ameghino"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Gutierrez, Marìa Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Pautasso, Andrés A.. Universidad Nacional de Rosario. Facultad de Ciencias exactas, Ingeniería y Agrimensura. Museo "Florentino y Carlos Ameghino"; Argentin

Selección de presas por el caracolero (Rostrhamus sociabilis) en cuerpos de agua permanentes y temporarios del centro de Argentina.

– En este estudio se analizó el patrón de selección de presas del caracolero (Rostrhamus sociabilis) sobre el caracol de agua dulce Pomacea canaliculata en la provincia de Buenos Aires, Argentina. Para esto se colectaron los restos presa de esta especie bajo las perchas de alimentación del caracolero y se colectaron individuos vivos de P. canaliculata en cinco cuerpos de agua temporarios y en tres lagunas. En cada localidad de muestreo, se comparó la distribución de frecuencias de los tamaños de los caracoles colectados de la población y de los caracoles predados por el caracolero. El caracolero seleccionó el tamaño de sus presas en todas las localidades; sin embargo, al patrón de selección difirió entre los diferentes tipos de ambientes. En las lagunas, el caracolero seleccionó presas de tamaño intermedio, pero en los cuerpos de agua temporarios seleccionó tanto las presas intermedias como las de mayor tamaño. A pesar de esto, el tamaño promedio de los caracoles predados en los cuerpos de agua temporarios fue 8–17 mm menor que en las lagunas. Las estimaciones de abundancia de caracoles (y, presumiblemente, su disponibilidad para los caracoleros) fueron mayores en los cuerpos de agua temporarios que en las lagunas. Las diferencias en la abundancia de presas y en la fisonomía del hábitat entre ambientes podrían ser responsables de las diferencias en el patrón de selección de presas observado.Prey selection by snail kites (Rostrhamus sociabilis) on freshwater apple snails (Pomacea canaliculata) was studied in permanent and temporary wetlands in Buenos Aires province, Central Argentina. Live individuals of P. canaliculata and prey remains of this species left under perches by snail kites were collected in five temporary and three permanent wetlands. Frequency distributions of size of live and preyed-upon snails were compared at each sampling locality. Although snail kites selected prey by size both in temporary and permanent wetlands, the pattern of prey selection differed between wetland types. Snail kites selected prey of intermediate size in permanent wetlands but in temporary wetlands they selected for intermediate and large-sized snails. In spite of this selection pattern, snail preyed by snail kites in temporary wetlands was on average 8–17 mm smaller than in permanent wetlands. Estimates of snail abundance (and presumably prey availability) were higher in temporary wetlands than in permanent wetlands. Differences in habitat physiognomy and in snail abundance between both types of habitat could be responsible for differences in the pattern of prey selection between wetland types.Fil: Mapelli, Fernando Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Kittlein, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Distribution, comportement migratoire et conservation du Synallaxe de Hudson Asthenes hudsoni (Furnariidae): un spécialiste des prairies de la pampa humide

Hudson’s Canastero, Asthenes hudsoni (Furnariidae) is a secretive passerine from the Rio de la Plata grasslands of South America. It is considered near threatened, but little is known about its distribution and seasonal movements. We performed a thorough revision of historical and recent records of the species and estimated its original and current geographic distribution using niche modeling based on climatic and land cover information. We found that A. hudsoni is not widespread across the Río de la Plata grasslands but mostly restricted to the humid pampas in Argentina, with isolated populations in central Argentina and SE Brazil. Most records north of the humid pampas in Argentina and Uruguay correspond to wintering individuals, revealing that the species is a partial seasonal migrant. Our distribution models indicate that its original area of occupancy may have been reduced by 65% to a current ~50,000 km², with a stronghold in the flooding Pampas in eastern Buenos Aires province. However, because of the specific microhabitat requirements of the species, we suspect that this figure underestimates the extent of appropriate habitat available, and that A. hudsoni could be very close to the threshold of area of occupancy for vulnerable species under IUCN criteria. Further research on habitat requirements, distribution, and population trends are urgently needed.Le Synallaxe de Hudson, Asthenes hudsoni (Furnariidae) est un passereau discret des prairies du Rio de la Plata en Amérique du Sud. Il est considéré comme quasi menacé, mais on sait peu de choses sur sa répartition et ses mouvements saisonniers. Nous avons effectué une révision complète des enregistrements historiques et récents de l'espèce et estimé sa distribution géographique originale et actuelle en utilisant un modèle de niche basé sur des informations climatiques et de couverture terrestre. Nous avons constaté que A. hudsoni n'est pas répandu dans les prairies du Río de la Plata, mais qu'il est surtout limité à la pampa humide en Argentine, avec des populations isolées dans le centre de l'Argentine et le sud-est du Brésil. La plupart des enregistrements au nord de la pampa humide en Argentine et en Uruguay correspondent à des individus hivernants, ce qui révèle que l'espèce est un migrateur saisonnier partiel. Nos modèles de distribution indiquent que sa zone d'occupation initiale pourrait avoir été réduite de 65% pour atteindre actuellement ~50 000 km², avec un bastion dans les pampas inondées de l'est de la province de Buenos Aires. Cependant, en raison des exigences spécifiques de l'espèce en matière de microhabitat, nous soupçonnons que ce chiffre sous-estime l'étendue de l'habitat approprié disponible et que A. hudsoni pourrait être très proche du seuil de la zone d'occupation des espèces vulnérables selon les critères de l'UICN. Il est urgent de poursuivre les recherches sur les exigences en matière d'habitat, la distribution et les tendances de la population.Fil: Claramunt, Santiago. University of Toronto; Canadá. Royal Ontario Museum; CanadáFil: Aldabe, Joaquín. Manomet Center For Conservation Sciences; Uruguay. Universidad de la Republica; UruguayFil: Etchevers, Ismael. Universidad de la Republica; UruguayFil: Di Giacomo, Adrian Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Kopuchian, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Milensky, Christopher M.. National Museum of Natural History; Estados Unido

The seasonal role of field characteristics on seed-eating bird abundances in agricultural landscapes

In temperate agroecosystems, avian responses in abundance and distribution to landscape attributes may be exacerbated by the coupling of natural seasons and farming practices. We assessed the seasonal roles of field type, field use in the surroundings, and distance from a field to the nearest woodlot on the abundance of seed-eating birds in a 225,000km2 study area in the Pampas of central Argentina. During spring-summer and autumn of 2011-2013, we randomly selected 392 fields and used transect samples to collect data on abundance and presence of seed-eating bird species. We recorded a total of 11,579 individuals belonging to 15 seed-eating bird species.We used generalized lineal mixed models to relate bird abundance to field type, field use in the surroundings, and distance to the nearest woodlot. In spring-summer (breeding season) most bird responses were associated with their nesting requirements. Species that build their nests in trees, such as eared doves Zenaida auriculata, picazuro pigeons Patagioenas picazuro, and monk parakeets Myiopsitta monachus, were more abundant in fields closer to woodlots, whereas grassland yellow-finches Sicalis luteola, which nest at areas with tall grasses, were more abundant in fields with livestock use patches in the field surroundings. In autumn (non-breeding season), most bird responses were associated with foraging and refuge needs. The high abundance of eared doves in crop stubbles and the association of pigeons at field surroundings dominated by croplands or at crop stubbles surrounded by livestock use fields revealed the intimate association of these species to sites with high availability of food resources. In addition, both picazuro pigeons and spot-winged pigeons Patagioenas maculosa were associated with woodlots, which provide suitable roosting sites. Our results show that in temperate agroecosystems, the relationships between field characteristics and seed-eating bird abundances vary with season.Centro de Estudios Parasitológicos y de Vectore

The seasonal role of field characteristics on seed-eating bird abundances in agricultural landscapes

In temperate agroecosystems, avian responses in abundance and distribution to landscape attributes may be exacerbated by the coupling of natural seasons and farming practices. We assessed the seasonal roles of field type, field use in the surroundings, and distance from a field to the nearest woodlot on the abundance of seed-eating birds in a 225,000km2 study area in the Pampas of central Argentina. During spring-summer and autumn of 2011-2013, we randomly selected 392 fields and used transect samples to collect data on abundance and presence of seed-eating bird species. We recorded a total of 11,579 individuals belonging to 15 seed-eating bird species.We used generalized lineal mixed models to relate bird abundance to field type, field use in the surroundings, and distance to the nearest woodlot. In spring-summer (breeding season) most bird responses were associated with their nesting requirements. Species that build their nests in trees, such as eared doves Zenaida auriculata, picazuro pigeons Patagioenas picazuro, and monk parakeets Myiopsitta monachus, were more abundant in fields closer to woodlots, whereas grassland yellow-finches Sicalis luteola, which nest at areas with tall grasses, were more abundant in fields with livestock use patches in the field surroundings. In autumn (non-breeding season), most bird responses were associated with foraging and refuge needs. The high abundance of eared doves in crop stubbles and the association of pigeons at field surroundings dominated by croplands or at crop stubbles surrounded by livestock use fields revealed the intimate association of these species to sites with high availability of food resources. In addition, both picazuro pigeons and spot-winged pigeons Patagioenas maculosa were associated with woodlots, which provide suitable roosting sites. Our results show that in temperate agroecosystems, the relationships between field characteristics and seed-eating bird abundances vary with season.Centro de Estudios Parasitológicos y de Vectore

Effect of environmental factors on the abundance variations of two native rodents in agricultural systems of Buenos Aires, Argentina

Our aim was to assess the effect of environmental factors on short temporal abundance variations of the two most abundant native rodents of agricultural agroecosystems, Akodon azarae and Calomys laucha. We conducted a 3-year longitudinal sampling of rodents, and recorded meteorological data such as temperature and precipitation, predation rate by Leopardus geoffroyi, Tyto furcata and Athene cunicularia, vegetation cover and height, characteristics of cropfields and their borders. The effect of these factors on rodent abundance was evaluated through generalized linear mixed models. Abundance variations of both rodent species were explained by characteristics of both cropfields and their borders. At the studied temporal scale, meteorological variables did not have a direct effect on abundance variations, but probably influenced through vegetation characteristics and were expressed in seasonal variations. For A. azarae there was also an effect of predation by L. geoffroyi (positive) and T. furcata (negative), while predation by A. cunicularia did not contribute to explain abundance variations of any species.Fil: Guidobono, Juan Santiago. 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; ArgentinaFil: Cueto, Gerardo Ruben. 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; ArgentinaFil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Busch, Maria. 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; Argentin

Diet of Cattle Egrets (Bubulcus ibis ibis) in the flood valley of the Paraná River, northern Argentina

Fil: Ducommun, María de la Paz. Instituto Nacional de Limnología (INALI, CONICET-UNL); Santo Tomé; Santa FeFil: Quiroga, Martín Aníbal. Instituto Nacional de Limnología (INALI, CONICET-UNL); Santo Tomé; Santa FeFil: Beltzer, Adolfo Héctor. Instituto Nacional de Limnología (INALI, CONICET-UNL); Santo Tomé; Santa FeFil: Schnack, Juan Alberto. Facultad de Ciencias Naturales y Museo; Universidad Nacional de La Plat

Lycalopex Gymnocercus (Carnivora: Canidae)

Lycalopex gymnocercus (Fischer, 1814) is a canid commonly called the Pampas fox. A sexually dimorphic fox-like carnivore of medium size with reddish coloration on sides and white on the ventral surface, it is 1 of 6 species in the genus Lycalopex. It occurs in eastern Bolivia, western and central Paraguay, Uruguay, north and central Argentina, and southeastern Brazil. It prefers open habitats but also occurs in areas of Pampas grassland modified by extensive ranching and agriculture activities. It has been assigned to the “Least Concern” category of the International Union for Conservation of Nature and Natural Resources.Fil: Lucherini, Mauro. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Cátedra de Fisiología Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; ArgentinaFil: Luengos Vidal, Estela Maris. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Cátedra de Fisiología Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentin

Arhythmorhynchus comptus (Acanthocephala: Polymorphidae) from shorebirds in Patagonia, Argentina, with some comments on a species of profilicollis

Adult and immature Arhythmorhynchus comptus (Acanthocephala: Polymorphidae) were found parasitizing the Baird’s Sandpiper, Calidris bairdii, and the White-rumped Sandpiper, Calidris fuscicollis (Aves: Scolopacidae), from several locations in Patagonia, Argentina. This is the first record of A. comptus in the southern part of South America and from C. fuscicollis and C. bairdii, expanding both its geographical and host distribution. Additionally, immature specimens belonging to the genus Profilicollis were found in both bird species.Centro de Estudios Parasitológicos y de Vectore

Taxonomy of the American Hebridae and the natural history of selected species

Dissertation (Ph.D.)--University of Kansas, Entomology, 1950