East-central Argentina Research Articles

The latest Carboniferous-earliest Permian palynological assemblage from the Sauce Grande Formation, Claromecó Basin, Argentina: Implications for the local palynostratigraphic scheme and correlations in Western Gondwana

The Sauce Grande Formation of the Ventania System and Claromecó Basin, east-central Argentina, is a geological unit of glaciomarine origin showing evidence of the glaciation that affected the supercontinent of Gondwana during the late Paleozoic. The age of this unit was previously determined from scarce and poorly preserved fossils, but mainly from radiometric dating and the fossil content of the overlying geological units. This study presents a palynological assemblage obtained from the Sauce Grande Formation in the PANG 0002 borehole, drilled in the Upper Paleozoic Claromecó Basin. Based on the identification of key species, such as Converrucosisporites confluens, Pakhapites ovatus, P. fusus, Vittatina spp., and Weylandites magmus, an age no older than Gzhelian is inferred for the interval studied. The inferred age allows us to relate the glaciomarine deposits of the Sauce Grande Formation to the last episode of the late Paleozoic Ice Age. The palynological assemblage of the Sauce Grande Formation is correlated with the Converrucosisporites confluens-Vittatina vittifera (CV) Biozone of the Claromecó Basin. Based on updated information and new correlations of the CV Biozone with palynostratigraphic schemes established in neighboring basins (Chacoparaná, Paraná, and central-western Argentina), its age is adjusted to the Gzhelian-late Artinskian interval, encompassing the Carboniferous-Permian boundary. This new information contributes to refining the current biostratigraphic scheme of the late Paleozoic Claromecó Basin.

Urban Parks Are Related to Functional and Phylogenetic Filtering of Raptor Assemblages in the Austral Pampas, Argentina

Urban parks are hot spots of bird diversity in cities. However, their role as urban filters for raptor species has not been assessed yet. This study aimed to compare the functional and phylogenetic traits of raptor assemblages in urban parks with the regional species pool of raptors in east–central Argentina. Diurnal raptors were surveyed in 51 urban parks in six cities during breeding and nonbreeding seasons. The regional species pool was assessed through raptor surveys and published maps surrounding the cities. The observed functional and phylogenetic relatedness of urban raptors was compared with 999 simulated raptor assemblages from the regional species pool. A total of five species were recorded in urban parks. The Chimango Caracara (Milvago chimango) was the numerically dominant species, comprising 95% of the 172 individuals recorded. The regional species pool was composed of 20 diurnal species. The functional and phylogenetic relatedness of urban raptors was higher than expected by chance, suggesting filtering induced by urban parks. Urban raptors were, in general, generalist species with small body sizes. Moreover, species tended to be part of the Falconidae family. Based on the results obtained here and in other published work, a model of raptor assembling in urban parks is proposed. The design of urban parks needs to be more heterogeneous, promoting the occurrence of specialist raptors.

Nesting biology of the Small-billed Elaenia (Elaenia parvirostris) in a forest with high conservation value in east-central Argentina

ABSTRACT Habitat loss and fragmentation significantly affect avian breeding success. East-central Argentina’s few native forests have become increasingly degraded by humans over time. Understanding the relationship between forest health and nesting success is critical since this information will be valuable as a point of comparison with future research if management actions are not taken. The study had two objectives: 1) describe the nesting biology of the Small-billed Elaenia (Elaenia parvirostris) and 2) assess whether a set of habitat features and time-specific variables had an effect on nest survival. We monitored 99 nests during three breeding seasons (2015–2018). Of all nests, 39% were successful, with predation causing the majority of nest failures (59%). We did not find important effects of habitat features on daily nest survival rate (DNSR). There was a cubic effect of nest age on the DNSR. Estimates of the cumulative probability to survive the entire nesting cycle was 41.2% (55.5% for egg laying, 16.1% for incubation, and 52% for nestling period). Our results add to the scientific understanding of life history strategies for south temperate birds while highlighting the need for additional research on native forest disturbances.

Soil and vegetation water content identify the main terrestrial ecosystem changes.

Environmental change is a consequence of many interrelated factors. How vegetation responds to natural and human activity still needs to be well established, quantified and understood. Recent satellite missions providing hydrologic and ecological indicators enable better monitoring of Earth system changes, yet there is no automatic way to address this issue directly from observations. Here, we develop an observation-based methodology to capture evidence of changes in global terrestrial ecosystems and attribute these changes to natural or anthropogenic activity. We use the longest time record of global microwave L-band soil moisture and vegetation optical depth as satellite data and build spatially explicit maps of change in soil and vegetation water content and biomass reflecting large ecosystem changes during the last decade, 2010-20. Regions of prominent trends (from [Formula: see text] to 9% per year) are observed, especially in humid and semi-arid climates. We further combine such trends with land cover change maps, vegetation greenness and precipitation variability to assess their relationship with major documented ecosystem changes. Several regions emerge from our results. They cluster changes according to human activity drivers, including deforestation (Amazon, Central Africa) and wildfires (East Australia), artificial reforestation (South-East China), abandonment of farm fields (Central Russia) and climate shifts related to changes in precipitation variability (East Africa, North America and Central Argentina). Using the high sensitivity of soil and vegetation water content to ecosystem changes, microwave satellite observations enable us to quantify and attribute global vegetation responses to climate or anthropogenic activities as a direct measure of environmental changes and the mechanisms driving them.

Multi-scale nest survival analysis suggests new cavities improve nest success for the Green-barred Woodpecker, but not the Campo Flicker, in a threatened woodland of Argentina

Abstract Understanding factors affecting nest survival of woodpeckers in threatened landscapes is a key tool for land managers, particularly when conservation depends on public policies. However, information of Neotropical woodpeckers breeding in southern temperate forests is noticeably sparse despite the worrying conservation status of these ecosystems and woodpeckers’ key role as cavity providers. Our objective was to assess the relationship between tree cavity features, vegetation structure, and landscape configuration on the nest survival of the Green-barred Woodpecker (Colaptes melanochloros) and the Campo Flicker (C. campestris). We monitored nests of these woodpeckers during 3 breeding seasons from 2015 to 2018 in a woodland of east-central Argentina threatened by selective tree logging and soil material extraction. We recorded features that presumably influence nest survival at a micro-scale (cavity, cavity-tree features, and foliage cover around the cavity) and a macro-scale (forest cover and shape index within a 500-m circle around the nest). We did not find support for a relationship between daily nest survival rates (DSR) and cavity features, vegetation structure, or landscape configuration. However, new cavities were more successful than reused ones for the Green-barred Woodpecker. We also found a surprisingly high rate (~33% of nest failures) of nest abandonment for both species. Abandonment may be a factor regulating this population and causes of abandonment warrants further investigation. Given the importance of new cavities to the success of Green-barred Woodpeckers, our results indicate the preservation of medium-size trees (20 cm < diameter at breast height [DBH] < 50 cm) with wood softened by degradation processes (preferred by the species to excavate cavities) would facilitate persistence both of this woodpecker and the cavity nesting community. Effective audit of soil material extraction and controlled selective timber logging practices (including preservation of mature trees) in compliance with existing regulations could contribute to this type of habitat maintenance.

Combined effects of agrochemical contamination and forest loss on anuran diversity in agroecosystems of east-central Argentina

Agricultural expansion and intensification has led globally to a rapid landscape structure change and high agrochemical use resulting in habitat loss and degraded environmental quality. Co-occurrence of landscape change and agrochemical contamination threatens biodiversity and might have interactive effects especially for organisms with complex life-cycles such as amphibians. We evaluated effects of landscape structure and agrochemical contamination at different spatial scales on anurans in Entre Rios, Argentina. We selected 35 independent stream headwaters along an agricultural expansion and intensification gradient. We conducted anuran call surveys from spring 2012 to summer 2013 and obtained detection-non detection data to estimate mean richness and focal species occupancy. We quantified forest area and riparian forest width at two spatial scales (sub-basin and local reach scale). We measured nutrients and pesticides in water and sediment. We evaluated anuran response to landscape and contamination variables using GLMs for richness and single season single-species occupancy models for focal species. Anuran diversity increased with forest area and riparian forest width, and decreased at sites with herbicide and nutrient contamination, particularly glyphosate; 2,4-D and nitrates. Also, most focal frog species responded mainly to basin forest and 2,4-D. Negative effects of agrochemical contamination on anuran diversity was mitigated in areas with larger basin forest cover. Agricultural management should ensure the reduction of herbicide and fertilizer use, the sparing of adequate forested habitat within drainage areas, and preservation of riparian forests around anuran breeding habitat to reduce and mitigate the negative effects of agrochemical contamination on anurans diversity in agroecosystems.

High levels of natal philopatry and no difference in reproductive success between philopatric and non-philopatric songbirds breeding in a native forests of east-central Argentina

ABSTRACT Philopatric birds have a number of advantages when breeding in familiar habitats, such as learning the locations of food, efficient movement throughout the breeding area, or effective escape from predators. However, few investigators have examined the possible effect of site familiarity on reproductive success, even less for Neotropical songbirds. We studied a breeding population of Masked Gnatcatchers (Polioptila dumicola) and Vermilion Flycatchers (Pyrocephalus rubinus), two south temperate songbirds, and examined the possible reproductive benefits of natal philopatry. In our population, 13.9% and 6.9% of breeding adults, respectively, for Masked Gnatcatchers and Vermilion Flycatchers, were philopatric. We found no difference in the breeding success between philopatric and non-philopatric individuals. Our results showed higher levels of philopatry for both species than previously reported for other songbirds. Because the remnants of native forests in our study area were located within a matrix of highly disturbed habitats, these intermediate-to-high values of natal philopatry could be linked to the structural characteristics of the forest that may force birds to use the few suitable forest patches available in the area.

The costs of ignoring species detectability on functional diversity estimation

AbstractFunctional diversity (FD) approaches have been increasingly used to understand ecosystem functioning in bird communities. These approaches typically rely on the assumption that species are perfectly detected in the field, despite the fact that imperfect detection represents a ubiquitous source of bias in biodiversity studies. This may be notably important in FD studies, because detection may depend on the functional traits used to compute FD metrics. However, little effort has been devoted to account for imperfect detection in FD studies, and therefore the degree to which species traits and detectability affects FD remains poorly understood. We predict that observed FD metrics may either underestimate or overestimate detection-corrected FD, because FD has multiple independent dimensions with different data properties. We assessed whether detection was related to bird traits (body mass, diet, and foraging stratum), accounting for habitat type, season, and phylogeny. We then used a multi-species occupancy model to obtain detection-corrected FD metrics (functional richness [FRic], functional evenness [FEve], and functional divergence [FDiv]), and compared observed and detection-corrected FD estimates in bird communities from east-central Argentina. Some functional types of birds (raptors and insectivores) were more easily overlooked, whereas others (seed and leaf eaters) were more easily detected. Some observed FD metrics underestimated detection-corrected FD (FRic and FDiv), whereas some others (FEve) overestimated detection-corrected FD. Both observed and detection-corrected FRic revealed differences between seasons, but not between habitat types. However, detection-corrected FEve and FDiv showed differences between seasons, contrary to observed estimates. Our results indicate that failure to account for unequal ease of detecting species can lead to erroneous estimates of FD because some functional types of birds are more easily overlooked. We outline some guidelines to help ornithologists identifying under which circumstances detection may be a concern and warn against the indiscriminate use of FD metrics without accounting for species detection.

Exotic trees fail as a support for Red-crested Cardinal (Paroaria coronata) nests in a native forest of east-central Argentina

Different tree species offer birds different types of bases for building the nests; those with thorns have been reported as important structural supports to contain and protect the nest from predators. We evaluate whether the tree used for nest support of the Red-crested Cardinal (Paroaria coronata) influences the durability and viability of the nests. Because the native forests of east-central Argentina are heavily altered by anthropic activity and coexist with a large number of exotic tree species, we assessed whether the frequency of broken-down nests before completing the nesting cycle varied between native and exotic trees. We monitored 207 nests in natural areas (all built on native trees) and 22 in modified habitats (seven on native trees and 15 on exotic trees). Among the nests built on native trees, the frequency of broken-down nests was lower in the Spiny Hackberry (Celtis ehrenbergiana) than in Scutia buxifolia and Schinus longifolius trees. Although all of them have thorns, we attribute this result to the tangled and zigzagging arrangement of C. ehrenbergiana branches that offer better support for the nests. On the other hand, the frequency of broken-down nests before completing the nesting cycle was higher in exotic trees, which raises concerns about the negative effect of the presence of exotic trees in the breeding areas of the Red-crested Cardinal. Considering the continuous invasion and expansion of exotic trees in these remnants of native forests, we suggest the authorities take measures to avoid new introductions and to control the progress of those that are already expanding, such as the worrying invasive tree Gleditsia triacanthos.

Craft Beer Market in Argentina: An Exploratory Study of Local Brewers’ and Consumers’ Perceptions in Mar del Plata

AbstractDuring the last twenty years, Argentina’s craft beer industry has experienced steady growth, which led to an increase in the number of both breweries and consumers. One of the first and most important craft beer clusters in the country is in Mar del Plata, a popular tourist destination on the coast in east-central Argentina. The sustained popularity of craft beer in this city provides an interesting case study to analyze thoroughly the evolution of a craft beer cluster in a developing country. This article aims to analyze producers’ perceptions as well as consumers’ preferences toward craft beer, in order to understand the craft beer drinkers’ decisions and choices. We interviewed five craft brewers and conducted two focus groups with local craft beer consumers. The results show that neolocalism is highly valued in the industry by both producers and consumers. We identify two groups of craft beer consumers: beginners or social consumers and sophisticated or craft beer lovers. The attributes most appreciated by consumers are quality, flavor, and bitterness.

The Craft Beer Market in Argentina: An Exploratory Study of Local Brewers’ and Consumers’ Perceptions in Mar del Plata

During the last twenty years, Argentina’s craft beer industry has experienced steady growth, which led to an increase in the number of both breweries and consumers. One of the first and most important craft beer clusters in the country is in Mar del Plata, a popular tourist destination on the coast in east-central Argentina. The sustained popularity of craft beer in this city provides an interesting case study to analyze thoroughly the evolution of a craft beer cluster in a developing country. This article aims to analyze producers’ perceptions as well as consumers’ preferences toward craft beer, in order to understand the craft beer drinkers’ decisions and choices. We interviewed five craft brewers and conducted two focus groups with local craft beer consumers. The results show that neolocalism is highly valued in the industry by both producers and consumers. We identify two groups of craft beer consumers: beginners or social consumers and sophisticated or craft beer lovers. The attributes most appreciated by consumers are quality, flavor, and bitterness.

Resource partitioning in a snake assemblage from east-central Argentina.

Two dimensions of the ecological niche (diet and habitat) of a snake assemblage from an endemic rich area in east-central Argentina, the Sierras de Ventania mountain chain, were analyzed. Field data collection was performed in 15-week study periods between 2010 and 2014. Snakes were hand-captured using transect surveys. Field observations on diet were analyzed together with stomach content data from museum specimens. Our results supported the partitioning of the snake assemblage by both habitat use and diet into at least three functional groups: species restricted to microhabitats under rocks and with a diet composed exclusively of ants (Epictia australis); species found mostly in stream microhabitats and feeding mainly upon anurans (Erythrolamprus poecilogyrus and Lygophis elegantissimus); and species found mostly in grassland microhabitats, with specialized diets of terrestrial prey items (Philodryas patagoniensis and Bothrops alternatus). Consistent with previous work, diet was more important than habitat in explaining ecological niche partitioning of this snake assemblage. Our results showed that high overlap values of microhabitat use were compensated by low overlap values of the trophic niche dimension, thus matching the traditional complementary niches hypothesis.

Comparative composition of the snake assemblage from Sierras de Ventania mountain range, east-central Argentina

ABSTRACTThe composition of a snake assemblage from an orographic island in east-central Argentina, the Sierras de Ventania mountain chain, was analyzed. The aim was to determine the biogeographic resemblance to other snake assemblages from neighboring regions. Species composition of each region was obtained from an exhaustive review of the literature, and both fieldwork and museum records. The higher biogeographic resemblance of the Sierras de Ventania occurred with the Sierras de Tandilia and the Coastal Dunes. These regions formed a well-defined group according to their snake assemblages. On the other hand, the Sierras de Lihué Calel linked to the Sierras de Ventania, and also to the rest of the compared regions, at very low values of biogeographic resemblance. The results obtained in this study contrasted with the classic zoogeographic scheme. Snake assemblages allowed recognizing a more significant division between Central and Pampean domains. In this scheme, the limit between these two regions moved to the southwest of the classical scheme; therefore the Sierras de Ventania was part of the Pampean domain. Also, the recognition of the Subtropical domain was evident, as well as its faunistic link with the Pampean domain.

Bacterial bioerosion in human and animal bones from subtropical environments (Northern Pampa/Middle Paraná River Basin, República Argentina)

Microbial bioerosion is a major diagenetic factor determining the long-term survival of archaeological bones as well as the quantity and quality of the biological information retrievable from them. In spite of this, information about bioerosion is still scarce from a worldwide perspective, with most of the data coming from the European continent. In this connection, the primary aim of this paper is to present the first results of an ongoing study oriented at identifying patterns of bacterial bioerosion in human and animal bone samples recovered at different Late Holocene archaeological sites from the subtropical environments of the Middle Paraná River Basin and the Northern Pampa Plain, República Argentina. These results differ in some respects from those obtained in other regions and climates, particularly the temperate belt of Europe, but are consistent with data from a nearer zone, the southern Pampas of East-Central Argentina. The main differences with most of the European samples investigated so far lie in the higher intensity of the bacterial attack on bones, which is reflected in the placement of the first and second frequency distribution modes at lower values of the Oxford Histological Index (0 and 3, respectively), an absence of cases with excellent histological preservation (i.e. OHI = 5) and, finally, a higher frequency and intensity of bioerosion in disarticulated animal bones and in those of humans interred as secondary burials. The causes of the observed differences are still not well understood, being probable that they are linked to higher levels of bacterial activity in the soils of this subtropical region of southern South America.

Urbanization as a driver of taxonomic, functional, and phylogenetic diversity losses in bird communities

Urbanization is one of the most important threats to biodiversity worldwide, as it drives declines in species diversity, functional diversity, and phylogenetic diversity and increases functional redundancy among species. We estimated taxonomic, functional, and phylogenetic diversities, as well as the abundance of several functional groups, in bird communities from a town in east-central Argentina in 1985–1986 and 30 years after (2015–2016). In 1985–1986, we found that taxonomic diversity (abundance, species richness, and alpha diversity), functional richness, and basal phylogenetic diversity were negatively related to building cover, whereas terminal phylogenetic diversity showed a positive relationship with building cover. Moreover, the abundance of specialized functional groups (ground, aerial, and foliage insectivores; nectarivores/insectivores; ground/canopy and ground granivores) decreased with increased building cover, whereas the reverse pattern for the abundance of generalists (medium-sized/large and small omnivores) was found. In 2015–2016, by contrast, taxonomic, functional, and phylogenetic diversities were not related to building cover. Our results not only support the hypothesis that urbanization affects the potential number of ecosystem functions, but also that this relationship may change through time. Given the accelerated rate of urbanization worldwide, an integrative approach between different facets of biodiversity is promoted to gain insight into the response of bird communities in urban environments.

Distributional patterns and conservation planning for a snake assemblage from temperate South America

We analyzed the spatial distribution of a snake assemblage from the Sierras de Ventania mountain range, a rich endemism area in east-central Argentina. We used field-collected and museum specimens combined with high-resolution environmental variables to identify common distributional patterns, estimate the suitable habitat for each species, and develop a conservation proposal related to the Protected Natural Areas (PNAs) system. Distributional models diverged into two opposite patterns: suitable habitats for most species at relatively high altitude in the hills, and suitable habitats for Bothrops ammodytoides and Lygophis anomalus at relatively low altitude in the surrounding hill plain. We assessed two proposals based on different conservation algorithms: the additive benefit function (ABF), which favours hilly environments, prioritizing areas with high specific richness, and the core-area zonation (CAZ), which prioritizes the distribution of all species, further indicating areas with low richness in the surrounding plain. Regardless of the algorithm used, our results indicated that the existing PNAs are not effective in protecting the snake assemblage. Protecting at least 5% of the highest species richness areas (ABF) or 5% of the distribution core areas of all species (CAZ), the existing PNAs only represented 2.2% of these priority areas. Our findings are largely consistent with previous work, highlighting that a widespread area needs to be assigned for conservation purposes. Thus, protection of the snake assemblage should take place both inside and outside the PNAs.

Rodent Abundance and Hantavirus Infection in Protected Area, East-Central Argentina.

We captured 3 hantavirus rodent hosts in Otamendi Natural Reserve, Argentina, during 2007–2012. Hantavirus antibodies were found only in Akodon azarae grass mice, mainly in males and old animals. Higher abundance of this species was associated with warm and rainy weather and high water levels, which peaked after a strong El Niño event.

Patch and landscape responses of bird abundance to fragmentation in agroecosystems of east-central Argentina

Fil: Calamari, Noelia Cecilia. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Entre Rios. Estacion Experimental Agropecuaria Parana; Argentina

Functional role of the invasive European Starling, Sturnus vulgaris, in Argentina

The introduction of exotic species may have severe effects on native ecosystems by disrupting communities and ecosystem services. Consequently, assessing the functional role of a species newly added to a community is an important task in order to identify native species at risk. In Argentina, the ecology of the invasive European Starling (Sturnus vulgaris) is poorly known and studies addressing its ecological role in bird communities are still lacking. We assessed the functional role of the European Starling by sampling bird communities across four vegetation types (Solanum grassland, Cynodon grassland, flood plain and forest patches) and making comparisons of body mass, and dietary and foraging traits of European Starling with native and other introduced bird species in east-central Argentina. The European Starling was functionally most similar to two widespread, generalist native passerines—the Bay-winged Cowbird (Agelaioides badius) and the Chalk-browed Mockingbird (Mimus saturninus)—and to the invasive House Sparrow (Passer domesticus), which together defined a functional group of terrestrial and foliage omnivores. European Starlings were more abundant in Solanum grasslands than in other vegetation types and showed significant vegetation-type overlap with functionally similar species. Moreover, abundance of European Starlings was positively correlated with bird abundance and diversity. Our results identify native species that are functionally equivalent to European Starlings, and, consequently, potentially subject to ecological impacts.

Queen replacement: the key to prevent winter colony losses in Argentina

Honey bee colony losses during winter are a multi-factorial phenomenon. Environmental conditions, beekeeping practices and different pathogens are all considered as potential causes of honey bee colony losses. However, these factors may be diverse in different regions and there are no regional studies about winter losses in South America. The objective of this study was to identify risks factors associated with winter losses in temperate climate honey bee colonies in Argentina. Parasitic mite infestation level, colony strength measures, and percentage of colonies losses during winter 2013 were evaluated in 62 apiaries distributed in four different regions in east-central Argentina. Data regarding management practices in each apiary were collected by means of a questionnaire. A logistic regression model was constructed to associate management variables with the risk of winter losses higher than 10% of the colonies. Beekeepers who reported replacing less than 50% of the queens in their apiaries showed higher winter losses than apiaries who replaced more than 50% of their queens (OR = 18.15; CI 95%: 1.76–187.43; p = 0.01). There were no significant spatial clusters detected in our analysis (p > 0.05). Even considering that the winter colony losses can be explained by a complex interaction of factors, requeening appears as one of the most important management practices to reduce this phenomenon in Argentina.