The areas devoted to agriculture that depend on pollinators have been sharply increased in the last decades with a concomitant growing global demand for pollination services. This forces to consider ...new strategies in pollinators' management to improve their efficiency. To promote a precision pollination towards a specific crop, we developed two simple synthetic odorant mixtures that honey bees generalized with their respective natural floral scents of the crop. We chose two commercial crops for fruit production that often coexist in agricultural settings, the apple (Malus domesticus) and the pear trees (Pyrus communis). Feeding colonies with sucrose solution scented with the apple mimic (AM) or the pear mimic (PM) odour enabled the establishment of olfactory memories that can bias bees towards the flowers of these trees. Encompassing different experimental approaches, our results support the offering of scented food to improve foraging and pollination activities of honey bees. The circulation of AM-scented sucrose solution inside the hive promoted higher colony activity, probably associated with greater activity of nectar foragers. The offering of PM-scented sucrose solution did not increase colony activity but led to greater pollen collection, which is consistent with pear flowers offering mainly pollen as resources for the bees. Results obtained from apple and pear crops suggest that the offering of AM- and PM-scented sucrose solution increased fruit yields. This preliminary study highlights the role of in-hive olfactory learning to bias foraging preferences within pome fruit crops.
The marsh deer (Blastocerus dichotomus, Illiger, 1815) is the largest contemporary South American deer, and its habitat includes the floodplains and wetlands of eastern South America. Throughout the ...Holocene these deer were widely used by indigenous societies, from the southern banks of the Amazon River to the Río de la Plata River, and from the Andean foothills to the Atlantic Ocean. However, despite the enormous ecological and archaeological importance of this ungulate in the region, our knowledge of the isotopic values of their diet is almost nonexistent. This paper is the first systematic approach to the study of the isotopic values of this mammal's diet, using archaeological and present-day samples from interconnected watersheds of the Paraná and Uruguay rivers in east-central Argentina. The results obtained from 24 measurements indicate an average value of −21.09 ± 1.46‰ in δ13C collagen, with a low coefficient of variation (6.92%). The data indicate a marked preference for consumption of plants with a C3 photosynthetic pathway. Most of the observed variability in the isotopic values corresponds to the period 900–1430 14C years BP, a time range during which the values show higher consumption of C4 plants. This it could be related with a period where temperature and associated humidity increased, synchronous in the area with the Medieval Climate Anomaly.
Display omitted
► The marsh deer is of enormous archaeological importance in South America. ► This represents the first systemic work on its isotopic diet (δ13C collagen). ► This deer has a plant-based diet C3 and C4 plants secondarily. ► Values average is (δ13Cco) −21.09‰ ± 1.46; variation coefficient 6.92‰. ► Major isotopic intake of C4 plants is synchronous to the medieval warm pulse.
Abstract
Anthropization processes confront local wildlife with a new set of conditions that may lead to local extinctions or allow the expansion of some species. This is what happens with the coypu ...(Myocastor coypus) in gated communities in the metropolitan area of Buenos Aires (Argentina), where its rapid population growth results in continuous conflicts with the local inhabitants. The aim of this study was to document the daily and seasonal activity patterns and behavior of the coypu in an urban landscape within their natural distribution range. To achieve this, we conducted a camera-trap survey within areas occupied by the species from February to November 2018. The coypu activity was mainly crepuscular and nocturnal with variations between seasons. We found that the seasons with the greatest activity patterns overlap were winter and autumn (84%), while the least overlap was observed between summer and winter (53%). During the active periods, time spent on foraging behavior was dominant. Time dedicated to vigilance was greater in summer than in winter. This result, alongside an increase in nocturnal activity during summer, shows that coypu in this urban landscape shift its behavior when exposed to an increasing human activity. This study brings up more ecological data of this species, which is key to find alternative control methods within gated communities to lead to a harmonic relationship between inhabitants and the species in its native distribution.
El carpincho (Hydrochoerus hydrochaeris) es un roedor semiacuático que habita en los humedales de tierras bajas tropicales, subtropicales y templados de Sudamérica. En este trabajo se analizó la ...mortalidad de una población de carpinchos y su relación con la disponibilidad de recursos en dos estaciones climáticohidrológicas contrastantes en una zona libre de presión de caza de los Esteros del Iberá, Argentina. Para ello, a fines del verano y del invierno, se estimó el número de individuos encontrados muertos y la estructura etaria y la proporción de sexos en los individuos muertos y la de 18 grupos sociales presentes en la población. Paralelamente, se analizaron las variaciones estacionales en la disponibilidad de alimento y refugio. El relevamiento de individuos muertos y la colección del material óseo se realizaron en 14 transectas de 3 km cada una. Se estimó la categoría etaria de los individuos en base al grado de osificación de las suturas basicraneales y el sexo de los adultos por el ancho de los incisivos. La mayor mortalidad de individuos se observó durante el invierno (140 vs. 49 en verano), siendo mayor para los adultos y, dentro de esta clase etaria, para los machos. Los estimadores de la disponibilidad de forraje y refugio fueron menores en el invierno. La disponibilidad de recursos sumado a las condiciones físicas del ambiente durante el invierno parecería estar incidiendo en la mortalidad de carpinchos y en su estructura poblacional.
The aim of this study is to propose a methodology to estimate the age of individuals of capybaras (
) using some morphometric measurements of the skull and femur. A sample of 250 individuals from ...different age categories was analyzed. These categories were estimated based on the ossification degree of the cranial sutures. Out of 28 morphocranial measurements taken, nine of them allow us to adequately determine the degree of bone maturation and the relative age: pre maxillonasal maximum width (MNW), pre maxillonasal minimum width (MNMW), parietal width (PW), intermaxillary width (IMW), maximum width of the 3rd molar (MW), minimum width of the 3rd molar (MMW), 3rd molar length (M3), molar length (ML), and molar 1 and 2 length (M12). In case of the femur, the measurements did not show differences among age categories, thus, we discarded these morphometric magnitudes as possible age indicators. This work proposes new measures to estimate and to analyze the relative age structure of the capybara population, providing a useful tool in the management and conservation of this species, and to evaluate paleontological and archaeological assemblages.
Within a species, home-range size can vary due to intrinsic and extrinsic factors. In this study we test the hypotheses that social group sizes (intrinsic) of capybaras (Hydrochoerus hydrochaeris) ...and food availability in their habitat (extrinsic) affect their home-range sizes. We used the minimum convex polygon method to estimate home-range sizes and core areas (the area in which each group was present during all seasons). Home-range size estimates varied from 11.3 ha to 27.6 ha (X̄ = 19 ha ± 1.89 SE). Core area accounted for a mean 22.5% of the total home-range size. Home ranges measured during autumn and winter were significantly larger than those recorded in spring and summer. The correlation between home-range size and mean number of adults in groups was marginally significant, whereas that between home-range size and the overall average group size was not significant. We observed a significant negative linear correlation between home-range size and estimators of food availability. The evidence that we determined does not allow us to establish any relationship between group size and home-range size, but it lends support to the hypothesis that the abundance of food resources is a major limiting factor in determining home-range size.
Pampas deer, armadillos and coypus: autochthonous mammals and land use changes, agricultural managements and presence of new elements in the rural landscape. Agriculture has been and still remains as ...a huge transforming power of our planet. In Argentina, agroecosystems of the pampas have also changed accordingly, led by agricultural expansion and the massive adoption of no-till system, along with territorial reorganization and intensification of livestock production. In turn, infrastructure (roads, channels, trenches) imposed new configurations to the rural landscape. How mammals have responded to these changes? Here we summarize the results recorded, among which we note: 1) a marked differential use of plots by the two most common species of armadillos, large hairy armadillos (Chaetophractus vittosus) more active in crop stubbles and southern long-nosed armadillos (Dasypus hybridus) more active in paddocks under livestock use, 2) the coexistence of Pampas deer (Ozotoceros bezoarticus) and cattle is only possible under grazing systems that provide resting periods to paddocks or under low stocking schemes, and 3) that coypu (Myocastor coypus) differentially use artificial channels in drier periods. Opportunities and challenges derived from these responses are discussed for the conservation of endangered species or the management of potentially conflicting species, as well as some future research needs are identified in terms of changes that continue to operate on these systems.
The capybara (Hydrochoerus hydrochaeris) is a selective herbivore that may show a preference for certain plant species. Such a preference is likely to be explained by the nutritional benefits ...hypothesis, stating that the nutritional value of species selected by capybaras is higher than that of avoided ones. Therefore, the objectives of this work are to evaluate the nutritional value of the plant species eaten by capybaras in the Lower Delta of the Paraná River, and to test the nutritional benefits hypothesis by analyzing forage quality. Samples of consumed plant species were collected from habitats located in the study area. We also collected plant species that are very abundant in the field but absent in the capybara's diet, some of which are consumed by other native herbivores such as coypus (Myocastor coypus). Their nutritional quality was analyzed by estimating the following variables: water content, ash percentage, percentage of organic matter, acid detergent fiber, nitrogen percentage, crude protein, and caloric energy. The protein to fiber ratio was calculated and the water content was determined. The species consumed and not consumed by capybaras had a similar nutritional composition for all the variables analyzed (P < 0.05). A similar result was observed when comparing within consumed species, except for the caloric energy content, which was significantly higher in species consumed in greater proportion than availability (P < 0.05). Water content was at its minimum in species consumed in greater proportion than availability, and at its maximum in unconsumed species. No significant differences were found between consumed Poaceae and the rest of the consumed plant species for any of the analyzed variables. Diet selection by capybaras in the studied area may only be partially related to nutritional quality, and there would be other factors involved in foraging, such as physiological mechanisms of the animal or chemical and structural characteristics of food.
En las poblaciones de carpinchos de los Esteros del Iberá se registran anualmente altas tasas de morbilidad/mortalidad durante las temporadas invernales, especialmente en ambientes artificiales. En ...este trabajo se estudiaron los parámetros poblacionales invernales de carpinchos en ambientes artificiales del área mencionada, y se analizó su estado sanitario. Se estimó la abundancia, tamaño de grupo, proporción de sexos, condición física y estructura etaria, y se evaluaron sanitariamente 25 carpinchos seleccionados al azar. Se realizaron estudios hematológicos y serológicos (brucelosis, tripanosomiasis y leptospirosis) y se identificaron los ectoparásitos y endoparásitos intestinales. Se observó una elevada abundancia poblacional (141.7 + ó - 55.9 individuos/km) y un tamaño de grupo de adultos de 13.9 + ó - 1.9 individuos. El índice de condición obtenido fue bajo (2.96). Se observó una alta prevalencia de ectoparásitos (Sarcoptes scabiei 90% y Ambíyomma dubitatum 95%) y endoparásitos (100%). No se detectó la presencia de brucelosis y tripanosomiasis, mientras que el 45.5% de los sueros estudiados para leptospirosis fueron seropositivos al menos para un serovar. Las hembras presentaron mayores valores de hemoglobina y concentración de hemoglobina corpuscular media. Las características físicas y biológicas de los tajamares y la alta densidad poblacional, parecerían afectar los parámetros poblacionales asociados (proporción de sexo y tamaño de grupo) y las condiciones sanitarias de sus poblaciones. Así, las altas cargas parasitarias y la mortalidad asociada a posibles infecciones secundarias, podrían actuar como moduladores de las poblaciones de carpinchos, especialmente en áreas protegidas y en ausencia de grandes depredadores.
PDF
