Seasonal effects on overlap trophic niche between capybara (Hydrochaeris hydrochaeris) and livestock and on trophic niche breadths in a rangeland of Central Entre Ríos, Argentina

QUINTANA, RUBEN DARIO

MAMMALIA

WALTER DE GRUYTER & CO

Año: 2003 vol. 67 p. 33 - 40

0025-1461

Foraging niche characteristics of capybara and livestock in Central Entre Ríos, Argentina, were studied. Seasonal diet composition was determined by microhistological analysis of faeces collected between 1990 and 1992. The diets of capybara and cattle included items of 26 plant species and 23 for sheep. The highest trophic niche breadth for the three species was found in spring, whereas the lowest was in summer for capybara and sheep and in winter for cattle. The trophic niche width of sheep was wider than those of capybaras and cows. Sheep and capybara were more selective than cows in summer, while cows were more selective than the formers in winter. Overlap of trophic niche among the three species varied from 77.8% between cattle and sheep in fall to 51.8% between capybara and sheep in summer. The percentages of diet overlap (>50%) suggest a grazing competition among the three species. The results of the present study show that spatial and temporal heterogeneity, in combination with the existing animal density might have considerable impact on the characteristics of the trophic niche of the herbivores under study. However, analysis of the characteristics of the trophic niche should be accompanied by analysis of the habitat use and segregation between the different herbivores in order to be drawn appropriate conclusions on the presence of competition