Mammals and their biomass on a Brazilian ranch

Abstract

Sixty-four species of wild mammals were recorded in deciduous forest, cerrado, and other vegetation types at Acurizal, a ranch located in the Pantanal area of southwestern Brazil. The total biomass of these species was about 380 kg/km² of which tapir contributed 25%, deer 22%, peccaries 15%, capybara 12%, edentates 8.5%, primates 5%, and carnivores 4%. Livestock had a biomass of over 3750 kg/km², a figure 10 times greater than that of the native mammals. The low biomass of wild mammals can be attributed to habitat modification (periodic floods, conversion of forest to pasture, annual grass fires), hunting for meat and hides, disease, especially in capybara, and seasonal changes in the abundance of fruit, leaves and other food. An analysis of food habits revealed several trends in resource use: terrestrial mixed browsers and grazers - tapir and deer - contributed most to the biomass; primary grazers were absent, except for the semi-aquatic capybara; and arboreal folivores were rare, comprising only howler monkey and porcupine, with 3% of the total biomass. Nearly 2/3 of the non-volant species,including various carnivores, subsist at least data from the Pantanal are compared with partly on seeds and fruit, and many species also eat insects and other invertebrates. In the seasonal environment of Acurizal, most species either have a flexible diet or specialize on a predictable resource. Biomass data from the Pantanal are compared with those from other neotropical areas, especially with the ecologically similar 11anos of Venezuela.