Excavations of giant armadillos alter environmental conditions and provide new resources for a range of animals in their southernmost range

Burrowing species can be considered important ecosystem engineers that increase landscape heterogeneity, create subterranean shelters and provide foraging opportunities. We measured and described different aspects of giant armadillo (Priodontes maximus) excavations (size, age), and differences generated in relation to the surrounding environment (vegetation, humidity, temperature) in three sites of the Argentine Chaco Region. We used camera-traps in two protected areas to monitor the use of burrows by other species and tested two primary and non-mutually exclusive hypotheses: Giant armadillo burrows are used as thermal protection from temperature extremes and provide new foraging opportunities for other species. Greater litter cover and depth were recorded in giant armadillo burrows, and more bare ground in spoil piles, producing habitat heterogeneity. Burrows had higher humidity and more moderate temperatures, with lower temperatures during hot months and higher temperatures during cold months. Out of 48 vertebrate species recorded by camera-traps, 27 taxa (17 mammals, 9 birds and one reptile) were recorded using burrows. White-lipped peccaries (Tayassu peccari) and collared peccaries (Pecari tajacu) used burrows more frequently than other mammals. Medium-sized carnivores such as Pampas fox (Lycalopex gymnocercus) and Geoffroy´s cat (Leopardus geoffroyii) tended to only investigate burrows, probably searching for prey. In no instances, animals other than giant armadillos were recorded staying inside burrows for more than a few seconds. Medium-sized species interacted more frequently than large-sized species, and smaller species used giant armadillo burrows less than larger ones, suggesting that the benefits provided by excavations to other species depend on their body weight. The probability of use of burrows decreases with time, suggesting that burrows provide a finite resource used opportunistically. Further reduction in the distribution of the giant armadillo is therefore likely to have effects on habitat heterogeneity and biodiversity, probably impacting the fitness of species that use their burrows as foraging sources.Fil: Di Blanco, Yamil Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; Argentina. Centro de Investigaciones del Bosque Atlántico; Argentina. Universidad Nacional de Misiones. Facultad de Ciencias Forestales; ArgentinaFil: Desbiez, Arnaud L. J.. Instituto de Conservação de Animais Silvestres; Brasil. Royal Zoological Society Of Scotland; Reino UnidoFil: Di Francescantonio, Débora. Centro de Investigaciones del Bosque Atlántico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Di Bitetti, Mario Santiago. Centro de Investigaciones del Bosque Atlántico; Argentina. Universidad Nacional de Misiones. Facultad de Ciencias Forestales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; Argentin

Relationship between morphology and trophic ecology in an assemblage of passerine birds in riparian forests of the Paraná River (Argentina)

We describe the ecomorphology of an assemblage of bird species found in riparian forests of the Middle Paraná River, Argentina. We sought to determine (1) the more important morphological characteristics that separate coexisting species, (2) whether such separation was related to the trophic ecology of each species and (3) whether a priori guilds showed morphological similarity. We tested the hypotheses that (a) a species' morphology is related to the trophic ecology of that species and (b) that species of a priori guilds are morphometrically more similar to each other than to species of different a priori guilds. For this, we considered an assemblage of 29 species of birds from riparian forest that were sampled with mist nets during the 2011 and 2014 breeding seasons. We obtained morphometric measurements of captured individuals and supplemented those data with measurements from museum specimens. Trophic characterisation (diet and trophic microhabitat) was based on a literature review. Results showed a separation of bird species as a function of variables related to trophic ecology (diets and trophic microhabitats) and morphology. After controlling for phylogenetic constraint, species' morphology partially reflected the trophic ecology of the species, supporting the central hypothesis of the ecomorphological discipline and showing that the use of trophic and morphometric data provides complementary data to improve the guild organisation of riparian bird assemblages.Fil: Quiroga, Virginia Mariela. 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: Lorenzón, Rodrigo Ezequiel. 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: Maglier, Gisela. Universidad Nacional del Litoral; ArgentinaFil: Ronchi Virgolini, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Autónoma de Entre Ríos; Argentin