Bom para quem? Influências positivas e negativas de uma espécie exótica invasora sobre populações de pequenos mamíferos

Abstract

In this study, we sought to evaluate how populations of two small mammal species, Trinomys iheringi and Didelphis aurita, behaved before, during and after the control of the alien species Artocarpus heterophyllus (jackfruit). The work was carried out in Ilha Grande State Park, located in the municipality of Angra dos Reis. The capture of small mammals occurred in the vicinity of Vila Dois Rios, from June 2006 to July 2016, totaling 93 monthly campaigns. To analyze the effects of the rodent demographic parameters, Trinomys iheringi and the marsupial, Didelphis aurita, we created mathematical models from parameters according to what we want to answer. The analyzes were done only with the two most abundant species, Trinomys iheringi and Didelphis aurita. For the T. iheringi species we captured a total of 374 individuals and for D. aurita, 126 individuals. For both species, the largest number of individuals captured occurred in the areas with jackfruits (252 individuals of T. iheringi and 126 of D. aurita), while in the areas without jackfruits we captured 122 and 32 individuals, respectively. Our results corroborate our hypothesis that small mammal populations responded positively to high density of jackfruits prior to initiation of control treatment. However, after the beginning of the control, the populations of the small mammals tend to diminish, since the jackfruit is a resource used by the two species. Consequently, the low availability of fruits and seeds of coats after treatment led, in general, to a decrease in the condition factor of individuals who were in areas with jackfruits