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1

The diet of field voles Microtus agrestis at low population density in upland Britain

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Wheeler P.

Acta Theriologica

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2005

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tom 50

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nr 4

483-492

Studies on field volesMicrotus agrestis Linnaeus, 1758 in lowland grasslands have shown them to be unselective grazers. The diet of the field vole in upland Britain was investigated using feeding trials with four of the dominant British upland monocots,Molinia caerulea,Nardus stricta, Deschampsia flexuosa and Eriophorum vaginatum. The suitability of faecal analysis was assessed and then used to analyse the diet of wild voles from faecal samples. Percentages of plant species in the faeces were compared to percentages on the ground in sites dominated byMolinia caerulea, Eriophorum vaginatum,Nardus stricta andCalluna vulgaris. Significant preferences for the grassDeschampsia flexuosa were observed in feeding trials and in the wild while the sedgeEriophorum vaginatum was avoided in both. There was no clear preference forMolinia caerulea andNardus stricta. Preference for plant species was related to palatability and nutrient content. The low nutrient conditions in British uplands mean that voles that live in these environments must be selective feeders to maximise nutrient intake.

2

Geographic and seasonal variability in feeding behaviour of a small herbivorous rodent

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Sassi P. L., Borghi C. E., Dacar M. A., Bozinovic F.

Acta Theriologica

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2011

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tom 56

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nr 1

Foraging strategies have traditionally been modelled as a result of food selection in response to one factor, as for instance resource availability, deterrent compounds or nutrients. Thus, a trade-off is assumed between plasticity (generalist strategy) and efficiency (specialist strategy). Nevertheless, several studies have demonstrated that animals cope behaviourally with food supply variation. For instance, desert-dwelling rodents partially compensate for nutritional bottlenecks through diet selection. The aim of our study was to test how foraging behaviour matches spatial and temporal variations in the trophic environment and how modelling hypotheses help us to understand the resultant foraging strategy. Our animal study model was the small cavy Microcavia australis, a widely distributed herbivorous rodent. Fieldwork was carried out in four places, in wet and dry seasons. We found significant differences in plant cover, plant diversity and niche breadth, and diet selection revealed a complex foraging strategy. M. australis shows a behavioural repertoire that exceeds single-criterion categories; therefore, we appeal to theoretical models that consider ecological and physiological perspectives. We classified the small cavy as a facultative specialist displaying a thoroughly opportunistic strategy based on the plasticity of the behavioural phenotype. We finally discuss the evolutionary relevance of our results and propose further investigation avenues.

3

Seasonal variation in feeding habits and diet selection by wild boars in a semi-arid environment of Argentina

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Cuevas M. F., Ojeda R. A., Dacar M. A., Jaksic F. M.

Acta Theriologica

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2013

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tom 58

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nr 1

The wild boar, Sus scrofa, was first introduced for hunting purposes in Argentina in 1906 and presently occupies a wide range of habitats. Understanding the food habits of invasive species is important for predicting the effects of animal food consumption on the environment and on human activities, such as farming. The wild boar is an omnivorous, opportunistic species whose diet is determined by the relative abundance of different types of foods. In general, the wild boar’s diet has been widely studied in the world, both as a native and invasive species, but little is known regarding food resource selection in the Monte Desert biome. Our study assessed the seasonal variation in the diet of wild boars, as well as the nutritional quality of consumed items. Further, we determined the diet selection of this species. Diet analyses were based on faecal samples collected over two seasons (wet and dry) in 1 year. Herbs were the most frequently consumed food item, with wild boars showing a selection for them in both seasons. The wild boar uses food resources according to seasonal availability (larger trophic niche breadth under higher plant diversity, as in the wet season). In turn, within each season, it selects items of high forage quality and high carbohydrate contents. In conclusion, this foraging strategy enables wild boar to maximize energy budget through food selection in order to survive in a semi-arid environment such as the Monte Desert.

4

Foraging strategy of plateau zokors (Eospalax baileyi Thomas) when collecting food for winter caches

100%

Xie J.-X., Lin G.-H., Zhang T.-Z., Su J. P.

Polish Journal of Ecology

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2014

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tom 62

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nr 1

Subterranean life style is characterized by limited food resource and energy consuming burrow behavior. Subterranean rodents are usually recognized as dietary generalists. In the current study, we investigated the species composition of winter caches of plateau zokors (Eospalax baileyi), and the dissimilarity of species composition in caches and in the vicinity of the burrows. We have made our research in Kobresia dominated vegetation at the altitude 3200 m a.s.l. We used the non-parametric method to test the similarities between the relative dry mass of the plant species within caches and their closed vicinity. This method was based on measures of distance between pairs of individual multivariate observations. Our results revealed that although plateau zokors cached most (60) of the plant species found in the vicinity of their burrow systems (66), the cached dry mass was dominated by a few species. Nine plant species accounted for 80% dry mass of plants present in zokors’ caches, Polygonum viviparum (50%) and other perennial poisonous forbs constitute 70% dry mass of the caches. Results showed that the dissimilarity between the relative dry mass of plant species within caches and in their vicinity was extremely significant (for Bray-Curtis distance measure, R = 0.355, P = 0.000; for Euclidean distance measure R =0.319, P =0.000). These results showed that plateau zokors don’t forage randomly when collecting food for winter caches. We suppose that rather than using a non-selective foraging strategy by dealing with high fiber-content plants, plateau zokors have forged another dietary strategy to meet the energy demands in the evolutionary process: to deal with poisonous forbs.

5

Diet selection by red-backed voles Clethrionomys gapperi

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Kasparian K., Millar J. S.

Acta Theriologica

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2004

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tom 49

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nr 3

Food supplementation studies often assume that animals will select artificial diets in their natural environment, and that high-protein, high-energy foods are the most appropriate supplement. These assumptions were tested in red-backed voles Clethrionomys gapperi Vigors, 1830 using food-choice experiments with sunflower seeds, oats, and commercial diets in the laboratory and field. Preferred level of dietary protein was also examined using isocaloric diets that varied only in protein content (14%, 20% and 30%). Preferences exhibited in the above trials were subsequently examined relative to natural forage. Voles demonstrated a strong preference for sunflower seeds over oats, dried alfalfa, and rabbit, guinea pig, rat and cat food. Voles preferred the 14% protein diet over the 20% and 30% protein diets. Although sunflower seeds contain more than 20% protein, voles consistently preferred this food over natural forage, perhaps because of their high fat and energy content. This indicates that tradeoffs in protein content may be made to maximize energy. We suggest that red-backed voles will select sunflower seeds in their natural environment, and that their preference for low protein likely reflects their herbivorous diet. This study highlights the importance of an a priori understanding of species-specific preferences and requirements when designing food supplementation studies.

6

Diet selection by Spanish ibex in early summer in Sierra Nevada

100%

Martinez T.

Acta Theriologica

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2000

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tom 45

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nr 3

Feeding strategy of the Spanish ibex Capra pyrenaica Schinz, 1838 was compared in two altitudinal zones of the Sierra Nevada, the high zone between 2700 and 3300 m a.s.l. and the mid-altitude zone between 2000 and 2700 m a.s.l. The study was carried out in July, and primarily focused on diet selection. Food availability, diet composition, species selection indices, and the effect of plant availability and chemical composition on diet selection in each zone were analysed. In the high zone, the availability of herbaceous resources was much greater than that of woody species, while in the mid-altitude zone, both resource types were almost equally abundant. Resource availability in both zones had a 36% index of similarity. Herbaceous plants were the predominant dietary component in both zones, and diet similarity was 51%. The greater similarity found between the two diet compositions than between the two resource availabilities revealed preferences for common species in both zones. The Spanish ibex selected food items with moderate levels in diet composition, a degree of quality (high protein content and digestibility) and moderate availability. In the high zone, the ibex selected its diet according to the protein content, while in the mid-altitude zone the food choice was mainly influenced by availability. Spatial heterogeneity probably influenced the difference detected in terms of the feeding strategy used in each area.

7

Differences in the nestling diets of sympatric Redstarts Phoenicurus phoenicurus and Black Redstarts P. ochruros: Species-specific preferences or responses to food supply?

80%

Sedlacek O., Fuchs R., Exnerova A.

Acta Ornithologica

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2007

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tom 42

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nr 1

99-106

8

Diet selection of the southern vizcacha (Lagidium viscacia): a rock specialist in north western Patagonian steppe, Argentina

80%

Galende G. I., Raffaele E.

Acta Theriologica

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2012

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tom 57

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nr 4

The southern vizcacha (Lagidium viscacia) is a rock specialist that inhabits small colonies in isolated rocky outcrops of northwestern Patagonia. This study analyzes its diet selection in relation to food availability, establishes the degree of dietary specialization, and discusses the potential competition with exotic herbivores. Diet composition and food availability were determined in summer and winter in eight rocky outcrops by microhistological analysis of fecal pellets, and food availability was estimated by the Braun Blanquet cover abundance scale. Vegetation cover differences were detected by using a random analysis of variance (ANOVA) factorial block design, and dietary preferences were determined by the confidence interval of Bonferroni. The southern vizcacha showed a specialized feeding behavior despite the consumption of a wide variety of items. Their diet was concentrated on a few types of food, mainly grasses, and the trophic niche was narrow and without seasonal variations. In winter, when food was scarce and of lower quality than summer, diet was dominated by Stipa speciosa, suggesting a selection according to the selective quality hypothesis. Our results (narrow trophic niche, restricted activity near rocky outcrops, and a diet with high proportions of low-quality grasses) showed that the vizcacha is an obligatory dietary specialist, and these characteristics made it highly vulnerable to changes in food availability. In this scenario, overgrazing caused by alien species with similar diets, as the European hare and livestock, could negatively affect their colonies.

9

Summer feeding strategy of Spanish ibex Capra pyrenaica and domestic sheep Ovis aries in South-Eastern Spain

80%

Martinez T.

Acta Theriologica

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2002

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tom 47

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nr 4

The feeding strategies of the Spanish ibex Capra pyrenaica Schinz, 1838 and sheep Ovis aries Linnaeus, 1758 during summer in the alpine area of Sierra Nevada in south-eastern Spain were compared. The degree of vegetation use by the two ungulates, food availability, diet composition, species selection indices and the effect of plant availability and chemical composition on diet selection were analysed. The available biomass of herbaceous and woody resources was 87 and 13%, respectively. The degree of use was 15% for herbaceous vegetation and 10.3% for woody vegetation. The most used species were those with moderate amounts in diet composition of both ruminants. The main plant groups consumed by Spanish ibex were graminoids (57.5%), shrubs (20.5%) and chamaephytes (14.3%). Sheep consumed graminoids (41.6%), forbs (32.3%) and chamaephytes (20.9%). There was a significant correlation between the two diets, with an overlap of 56.3%. The highest indices of selection were found in items with moderate-low availability and which comprised moderate levels in the diet composition of the two species. Spanish ibex mainly selected diet according to availability, while sheep selection depended on protein content. The ibex consumed cell wall-rich resources such as grasses and shrubs, while the sheep consumed higher quality feed and includes more forbs in its diet.

Ograniczanie wyników

The diet of field voles Microtus agrestis at low population density in upland Britain

Geographic and seasonal variability in feeding behaviour of a small herbivorous rodent

Seasonal variation in feeding habits and diet selection by wild boars in a semi-arid environment of Argentina

Foraging strategy of plateau zokors (Eospalax baileyi Thomas) when collecting food for winter caches

Diet selection by red-backed voles Clethrionomys gapperi

Diet selection by Spanish ibex in early summer in Sierra Nevada

Differences in the nestling diets of sympatric Redstarts Phoenicurus phoenicurus and Black Redstarts P. ochruros: Species-specific preferences or responses to food supply?

Diet selection of the southern vizcacha (Lagidium viscacia): a rock specialist in north western Patagonian steppe, Argentina

Summer feeding strategy of Spanish ibex Capra pyrenaica and domestic sheep Ovis aries in South-Eastern Spain