Densidade, tamanho populacional e conservação de primatas em fragmento de Mata Atlântica no sul do Estado de Minas Gerais, Brasil

Population estimates of the endangered Callithrix aurita and Callithrix hybrids records in a large Atlantic Forest remnant

Forest-dependent species are among the most threatened species due to landscape changes, and this is the case of the buffy-tufted-ear marmoset (Callithrix aurita), an Atlantic Forest endemic primate. Besides its extensive habitat reduction across Atlantic Forest, the species suffers from the negative impact of the presence of non-native congeners that threatens its local populations due to competition and hybridization events. Knowing the population status of this endangered species is important to guide conservation efforts. Thus, we estimated the population density of C. aurita and recorded the presence of invasive Callithrix species and Callithrix hybrids in Serra do Japi, a large forest remnant with mountainous terrain within the most human-populated region of the State of São Paulo, Brazil. We surveyed a 14.8 km2 area with 387.2 km of survey effort. We estimated a sighting rate of 4.4 groups/10 km walked. The maximum number of individuals recorded per group ranged from 7 to 12. We identified 15 groups throughout the sampled area, totalling 1.01 groups/km2. Two individuals from two distinct groups presented body pelage characteristic of hybrids between C. aurita and other Callithrix species. No individuals of other Callithrix species were recorded within the surveyed area. Considering the total size of this remnant and the potential population size of C. aurita inhabiting this area, this local population may be an important source of individuals for helping the conservation and long-term persistence of the species. However, the presence of Callithrix hybrids in the area is worrying and may threaten the local native population. Our study reinforces the concern with C. aurita conservation and the need for studies focused on the management of hybrids and invasive Callithrix species. Mitigation measures should be directed to readily control hybridization to keep this large population of Serra do Japi safe.

An Introduction to the Callithrix Genus and Overview of Recent Advances in Marmoset Research

We provide here a current overview of marmoset (Callithrix) evolution, hybridization, species biology, basic/biomedical research, and conservation initiatives. Composed of 2 subgroups, the aurita group (C aurita and C flaviceps) and the jacchus group (C geoffroyi, C jacchus, C kuhlii, and C penicillata), this relatively young primate radiation is endemic to the Brazilian Cerrado, Caatinga, and Atlantic Forest biomes. Significant impacts on Callithrix within these biomes resulting from anthropogenic activity include (1) population declines, particularly for the aurita group; (2) widespread geographic displacement, biological invasions, and range expansions of C jacchus and C penicillata; (3) anthropogenic hybridization; and (4) epizootic Yellow Fever and Zika viral outbreaks. A number of Brazilian legal and conservation initiatives are now in place to protect the threatened aurita group and increase research about them. Due to their small size and rapid life history, marmosets are prized biomedical models. As a result, there are increasingly sophisticated genomic Callithrix resources available and burgeoning marmoset functional, immuno-, and epigenomic research. In both the laboratory and the wild, marmosets have given us insight into cognition, social group dynamics, human disease, and pregnancy. Callithrix jacchus and C penicillata are emerging neotropical primate models for arbovirus disease, including Dengue and Zika. Wild marmoset populations are helping us understand sylvatic transmission and human spillover of Zika and Yellow Fever viruses. All of these factors are positioning marmosets as preeminent models to facilitate understanding of facets of evolution, hybridization, conservation, human disease, and emerging infectious diseases.

Dramatic decline in a titi monkey population after the 2016-2018 sylvatic yellow fever outbreak in Brazil

Platyrrhini are highly vulnerable to the yellow fever (YF) virus. From 2016 to 2018, the Atlantic Forest of southeast Brazil faced its worst sylvatic YF outbreak in about a century, thought to have killed thousands of primates. It is essential to assess the impact of this epidemic on threatened primate assemblages to design effective conservation strategies. In this study, we assessed the impact of the 2016-2018 YF outbreak on a geographically isolated population of Near Threatened black-fronted titi monkeys (Callicebus nigrifrons) in two Atlantic Forest patches of the Santuário do Caraça, MG, Brazil. Extensive preoutbreak monitoring, conducted between 2008 and 2016, revealed that the home range and group sizes of the population remained stable. In 2016, the population size was estimated at 53-57 individuals in 11-12 groups. We conducted monitoring and playback surveys in 2019 and found that the population had decreased by 68% in one forest patch and completely vanished in the other, resulting in a combined decline of 80%. We discuss this severe loss of a previously stable population and conclude that it was highly likely caused by the YF outbreak. The remaining population is at risk of disappearing completely because of its small size and geographic isolation. A systematic population surveys of C. nigrifrons, along other sensible Platyrrhini species, is needed to re-evaluate their current conservation status.

Transverse lie with prolapsed arm in a female red-howler monkey (Alouatta guariba clamitans - Cabrera, 1940)

This study focuses on a case of a red-howler monkey (Alouatta guariba clamitans) which was found with a fetus in a transverse lie position with a prolapsed arm. The topic of this research is well justified as there are no data on this condition involving this type of non-human primate in literature. In this study, a red-howler monkey was observed by locals pulling at her pelvic region for 3 days near a farm. On the third day, the monkey was found lying on the ground at which point she offered no resistance when approached. The environmental police took the monkey to receive medical attention. During the physical examination, it was quickly observed that the monkey was pregnant; the right forelimb of the fetus was exposed from the vulva. An ultrasound revealed a non-viable fetus, and due to the severe weakness of the mother, we opted for euthanasia. During the necropsy, not only was the fetus found macerated but it was also in a transverse lie position with a prolapsed arm and presented no external or internal injuries consistent with trauma.