Relative importance of anthropogenic landscape characteristics for Neotropical frugivores at multiple scales

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.

Framing pictures: A conceptual framework to identify and correct for biases in detection probability of camera traps enabling multi-species comparison

Obtaining reliable species observations is of great importance in animal ecology and wildlife conservation. An increasing number of studies use camera traps (CTs) to study wildlife communities, and an increasing effort is made to make better use and reuse of the large amounts of data that are produced. It is in these circumstances that it becomes paramount to correct for the species- and study-specific variation in imperfect detection within CTs. We reviewed the literature and used our own experience to compile a list of factors that affect CT detection of animals. We did this within a conceptual framework of six distinct scales separating out the influences of (a) animal characteristics, (b) CT specifications, (c) CT set-up protocols, and (d) environmental variables. We identified 40 factors that can potentially influence the detection of animals by CTs at these six scales. Many of these factors were related to only a few overarching parameters. Most of the animal characteristics scale with body mass and diet type, and most environmental characteristics differ with season or latitude such that remote sensing products like NDVI could be used as a proxy index to capture this variation. Factors that influence detection at the microsite and camera scales are probably the most important in determining CT detection of animals. The type of study and specific research question will determine which factors should be corrected. Corrections can be done by directly adjusting the CT metric of interest or by using covariates in a statistical framework. Our conceptual framework can be used to design better CT studies and help when analyzing CT data. Furthermore, it provides an overview of which factors should be reported in CT studies to make them repeatable, comparable, and their data reusable. This should greatly improve the possibilities for global scale analyses of (reused) CT data.