Diet Selection by the Fossorial Rodent Ctenomys mendocinus Inhabiting an Environment with Low Food Availability (Mendoza, Argentina) (original) (raw)
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Dietary preferences of two sympatric subterranean rodent populations in Argentina
Revista Chilena de …, 1995
We determined the dietary habits of two sympatric and allotopic populations of Ctenomys (C. australis and C. talarum) that inhabit a natural dune grassland on the sea coast at Necochea, Buenos Aires Province, Argentina. Both species were found to be generalist herbivores as they consumed almost all plant species available in the grassland. Contrary to what we had expected, they fed principally on the aerial fraction of the vegetation, and preferred grasses overforbs. The greater proportion of the subterranean fraction in autumn and winter in C. australis diets compared to C. tala rum might be related to differences in the vegetation around the burrows they inhabit. Ctenomys australis and C. talarum diets differed markedly only in September; however, these differences may not have been totally seasonal, there may also have been a spatial effect due to the soil structure of the sympatric area. Ctenomys australis and C. tala rum distributions seem to be related to soil characteristics with individual animals feeding and selecting mainly among the vegetal species in their own home range. The results of this study show that these species of Ctenomys present a feeding strategy which is adaptative in subterranean rodents due to their high digging cost and to the low available energy to explore in their subterranean environment.
Dietary Habits of the Common Rodents in an Agroecosystem in Argentina
Journal of Mammalogy, 1998
Dietary habits of five common rodents in agroecosystems on the central Argentine Pampa were studied for 15 months using microhistological analysis of stomach contents. All five rodent species were omnivorous, but proportions of major dietary items (arthropods, dicot leaves and seeds, monocot leaves and seeds) varied among species and seasons. Akodon azarae largely was entomophagous; arthropods formed 41-62% of the diet in all seasons. The other four species (Calomys musculinus, Calomys Zaucha, Bolomys obscurus, and Oligoryzomys flavescens) consumed most diet items throughout the year, but relative proportions varied among seasons. Leaves fonned a relatively minor proportion of the diet (12-16% overall for all species) throughout the year. All species except A. azarae consumed higher quantities of seeds (50-73% of stomach volume) than arthropods (15-35%) during autumn and winter but switched to higher quantities of arthropods (30-53%) in spring and summer. Diet breadth was narrower and overlap generally highest during winter when all species were forced to subsist on a reduced set of available resources. Of 28 plant species with >2% cover in the environment, 25 were identified in stomachs of one or more of the five rodent species. The most important plant species in the diet were corn and soybeans (mostly grain), seed of Johnson grass (Sorghum halepense), chickweed (Stellaria media), and Amaranthus. High consumption of arthropods, especially by A. azarae, contraindicates the broad-scale use of rodenticides until the role of that rodent species in the control of pest insects can be ascertained.
Dietary Habits of the Common Rodents in an Agrecosystem in Argentina
1998
(KTM) Dietary habits of five common rodents in agroecosystems on the central Argentine Pampa were studied for 15 months using microhistological analysis of stomach contents. All five rodent species were omnivorous, but proportions of major dietary items (arthropods, dicot leaves and seeds, monocot leaves and seeds) varied among species and seasons. Akodon azarae largely was entomophagous; arthropods formed 41-62% of the diet in all seasons. The other four species (Calomys musculinus, Calomys laucha, Bolomys obscurus, and Oligoryzomys flavescens) consumed most diet items throughout the year, but relative proportions varied among seasons. Leaves formed a relatively minor proportion of the diet (12-16% overall for all species) throughout the year. All species except A. azarae consumed higher quantities of seeds (50-73% of stomach volume) than arthropods (15-35%) during autumn and winter but switched to higher quantities of arthropods (30-53%) in spring and summer. Diet breadth was narrower and overlap generally highest during winter when all species were forced to subsist on a reduced set of available resources. Of 28 plant species with >2% cover in the environment, 25 were identified in stomachs of one or more of the five rodent species. The most important plant species in the diet were corn and soybeans (mostly grain), seed of Johnson grass (Sorghum halepense), chickweed (Stellaria media), and Amaranthus. High consumption of arthropods, especially by A. azarae, contraindicates the broad-scale use of rodenticides until the role of that rodent species in the control of pest insects can be ascertained.
Main food categories in diets of sigmodontine rodents in the Monte (Argentina)
Mastozoología …, 2005
The present study aims at improving the characterization of the dietary status of four sigmodontine rodents (Graomys griseoflavus, Akodon molinae, Calomys musculinus and Eligmodontia typus) by quantifying the major food categories (leaves, stems, seeds, Prosopis flexuosa pods, and arthopods) with a modified microhistological technique. The use of this new technique enhances the likelihood of accurately identifying plant parts, such as stems, seeds and fruits that are usually underestimated. Results reveal that hard tissues, like seeds, are a major resource in the diets while other hard tissues, such as stems and P. flexuosa pods, appear for the first time in the diet of all four species of sigmodontine rodents. Rodent species display considerable trophic flexibility that may be particularly advantageous in arid environments where resource availability is unpredictable and heterogeneous.
Mastozoología …, 2005
The present study aims at improving the characterization of the dietary status of four sigmodontine rodents (Graomys griseoflavus, Akodon molinae, Calomys musculinus and Eligmodontia typus) by quantifying the major food categories (leaves, stems, seeds, Prosopis flexuosa pods, and arthopods) with a modified microhistological technique. The use of this new technique enhances the likelihood of accurately identifying plant parts, such as stems, seeds and fruits that are usually underestimated. Results reveal that hard tissues, like seeds, are a major resource in the diets while other hard tissues, such as stems and P. flexuosa pods, appear for the first time in the diet of all four species of sigmodontine rodents. Rodent species display considerable trophic flexibility that may be particularly advantageous in arid environments where resource availability is unpredictable and heterogeneous.
Journal of Arid Environments, 2009
Overgrazing by livestock has caused desertification in the Monte, where ctenomyids and livestock share grasses as main food items. The diet of Ctenomys eremophilus, above-ground food availability and changes related to cattle grazing are analyzed in the arid plain of Mendoza, Argentina. The most available categories were grasses, followed by low shrubs and tall shrubs. Tuco-tucos showed dietary generalism, ate mainly above-ground plant parts, preferred grasses and avoided shrubs at both grazed and ungrazed sites. Plant cover, grass diversity and availability decreased under livestock grazing, which was reflected in the diet by a lower percentage of grasses, a shift toward low shrubs and higher number of frequently used resources. Tuco-tucos in the grazed paddock compensated for lower consumption of vegetative plant parts by increasing the use of Prosopis flexuosa pods stored inside burrows. Moreover, greater dietary variation among individuals suggests foraging restricted to the items closest to burrow holes. These feeding tactics would allow them to reduce above-ground foraging as a response to high raptor predation risk due to increased bare soil. The plant recovery detected during the rest period, favoured by moderate stocking rate and rotational grazing system, would allow coexistence of tuco-tucos and cattle.
Diet of a sigmodontine rodent assemblage in a Peruvian montane forest
Journal of Mammalogy, 2015
Knowledge of feeding habits of small rodents is necessary for understanding food webs, trophic structure, and plant-animal interactions in Neotropical forests. Despite several studies that have investigated community structure and feeding behavior of rodents, large gaps remain in our understanding of their guild occupancy. Our objective was to investigate the diets of 7 species of small (< 100 g) sympatric sigmodontine rodents in a high (3,500 m) Andean montane rainforest in Peru. We qualitatively and quantitatively assessed diet items in fecal samples from livetrapped rodents from 2009 to 2012. Frequency data for 4 diet categories indicated that all 7 species of rodents contained 4 diet categories in fecal samples: arthropods (88%), remains of leaves and fibers from plants (61%), intact seeds (with or without fruit pulp; 50%), and mycorrhizal spores (45%). Omnivory was found to be a strategy used by all species, although contingency table analysis revealed significant differences among and within species in diet categories. Cluster analysis showed 2 main groupings: that of the Thomasomys spp. plus Calomys sorellus group which included high amounts of intact seeds and plant parts in their fecal samples, and those of the genera Akodon, Microryzomys, Oligoryzomys, which included a greater proportion of arthropods in their fecal samples, but still consumed substantial amounts of fruit and plant parts. Intact seed remains from at least 17 plant species (9 families) were found in fecal samples. We concluded that this assemblage of sigmodontine rodents is omnivorous but that they likely play an important role as frugivores and in seed dispersal in tropical montane forests in Peru.
Journal of Arid Environments, 2010
The feedback between organisms and their environment is of great relevance to the understanding of ecosystem functioning. Particularly, subterranean mammals living on desert systems play an important role in ecosystem processes modifying their environment and influencing the life strategies of plants and animals. The mendocino tuco-tuco Ctenomys mendocinus, is a fossorial rodent inhabiting a wide range of soil and climate conditions in the central arid lands of Argentina. The purpose of our study was to quantify the degree of environmental segregation: soil properties and vegetation in four habitat types, their impact on woody vegetation, and diet. The highest activity was recorded in sand dunes and was associated with high habitat heterogeneity and soft soils. Degree of herbivory varied among habitats, with Lycium (Solanaceae) being the most gnawed shrub. Tuco-tucos behave like folivorous grazers, feeding on leaves of grasses, mostly Panicum (Poaceae). This is the first study integrating multiple approaches of tucos' auto-ecology in a heterogeneous desert matrix, suggesting a differential use of its environment, possibly according to food supply and soil hardness. Despite life underground impose general constrains for most subterranean species, our results suggest that both above and under ground habitat features play important roles in the occurrence of fossorial rodents.
The partitioning of food resources between two rodents in the subtropical region of southern Brazil
Anais da Academia Brasileira de Ciências, 2017
The capybara (Hydrochoerus hydrochaeris) and nutria (Myocastor coypus) are herbivorous semi-aquatic rodents. Although these rodents occur in sympatry in southern South America, little is known about how the two species interact in relationship to food resources. In this context, the aim of this study was to analyze the food resource overlap, the feeding strategy and the diversity of the diet of capybaras and nutria. A micro-histological analysis of feces was used to study the diets. A total of 48 plant species belonging to 10 families were identified in the diet of H. hydrochaeris, and a total of 49 species belonging to 14 families were identified in the diet of M. coypus. According to the Amundsen graphical method, both rodents adopted a specialized strategy for feeding on Poaceae and a generalized strategy for other families. The results of a multivariate analysis of the dietary data showed significant differences between the two rodent species and among the seasons. These differences between diets may be related to the different proportions of each food item eaten. However, the dietary overlap between the two rodents in the Taim wetland was high, suggesting that partitioning of other resources ensured the coexistence of the species.