An endangered native species is being replaced by hybrids: the new normal for primate conservation in the Brazilian Atlantic Forest

Abstract

Biological invasions can interfere decisively with the dynamics of important ecological processes.For primates of the genus Callithrix (marmosets), congener introductions and hybridization represent one of the greatest threats to native species. The Rio Doce State Park (RDSP), in southeastern Brazil, has records of three species of Callithrix, the endangered native species C. aurita, and two species of introduced marmosets, C. geoffroyi and C. penicillata.We used the playback method combined with adapted N-mixture models to estimate abundance and detection probability for Callithrix spp. in relation to biological variables. We estimated a total of 139 individuals, equivalent to 0.12 ind./ha, all being hybrids, except for one individual of C. aurita observed in a group of hybrids.The abundance of Callithrix spp. was higher in locations close to the forest edge, possibly due to the high availability of insects and greater availability of shelters in these areas.The detection probability of Callithrix spp. correlated positively with precipitation, indicating that greater humidity, as well as greater availability of arthropods, may favor the detection of individuals due to their high foraging activity during these periods. The results of this study show the critical scenario of biological invasions in RDSP, with serious threats to the native species.We suggest urgent and integrated measures to contribute to the conservation of C. aurita, such as a management plan for the few individuals of the native species. The unprecedented adaptation of the N-mixture model showed effectiveness for estimate abundance and detection probability of acoustically-responsive primates such as species of the genus Callithrix.