Camera traps in Chinko

Help us find the animals in the pictures !

Results

What are the data collected for?

The data collected with camera traps can then be used in a variety of ways. Here we present some of the studies already published in which we have used the data.

Tracking population trends in the park

Knowing the state of the reserve's animal populations is very important for biodiversity conservation. Several anti-poaching measures have been put in place in recent years, and we wanted to find out what impact they have had on the reserve's animal populations. To do this, we looked at the population trends of four apex predators and six of their prey before and after the measures were implemented. Using track count and camera trapping data obtained between 2012 and 2024 in the Chinko Conservation Area, we noted that the African buffaloes, Defassa waterbucks, Giant eland antelopes and Lelwel hartebeests had a declining population before the measures and now have a growing population thanks to the measures implemented (the X axis on the graph below represents the population before the measurements, and the Y axis the population after the measurements). No change was noted in the population of Lowland bongo antelopes, for which we speculated that due to their use of close-canopy forests and their elusive behavior, they were barely affected by direct poaching by herders. As for the apex predators, the Wild dog, Leopard and Lion populations were in decline before the anti-poaching measures were taken, and has shown an increase since. The Spotted hyena population has changed very little, which could mean that in contrast to lions, hyenas were not directly targeted by poaching herders.

These encouraging results prove that conservation measures are bearing fruit, and that they are necessary!

Figure 7: Analysis of survey data from the Chinko. Shown are two dimensional posterior densities for the trends before (γ1, x-axis) and since active law enforcement was enacted(γ2, y-axis) for four apex predator species (right, brown) and six of their potential prey species (left, blue). The total number of observations is shown in the top-left corner; the posterior support for a more positive trend since law enforcement was enacted in the lower-right corner.

Article : Singer, L., Caduff, M., Aebischer, T., Tabiti, P., Freiberg, A., Ingensand, J., ... & Wegmann, D. (2025). Testing for changes in population trends from low-cost ecological count data. bioRxiv, 2025-01.
https://doi.org/10.1101/2025.01.08.631844

Another article also showing the demographic trends of populations in the park: Aebischer, T., Ibrahim, T., Hickisch, R., Furrer, R. D., Leuenberger, C., & Wegmann, D. (2020). Apex predators decline after an influx of pastoralists in former Central African Republic hunting zones. Biological Conservation, 241, 108326.
https://doi.org/https://doi.org/10.1016/j.biocon.2019.108326

Learn about species distribution

Even today, certain ecosystems and the species that live there are poorly understood; this lack of data may be due to the difficulty of access or the lack of resources invested in such research. A particularly understudied wilderness area is the Eastern Central African Republic (CAR), a heterogeneous ecotone of pristine moist forests and open savanna woodlands.

We showed the importance of camera traps, transect walks and collected fecal samples in determining the distribution of the region's chimpanzees (Pan troglodytes). We discovered a sizeable and reproducing population of chimpanzees east of the Chinko River ! Based on a density of 0.81 chimpanzees/km2 in closed canopy forest that we inferred from nest count data, we estimate 910 weaned chimpanzees to inhabit the Chinko Nature Reserve (CNR) and further predict additional 2700 individuals in adjacent, unmanaged hunting zones and reserves. Highlighting this large chimpanzee population in the reserve helped explain the need for protective measures.

Fig. 2. Study area between the three major rivers, Mbari, Chinko and Vovodo within the assumed species range of chimpanzees (IUCN SSC A.P.E.S. database, Drexel University and Jane Goodall Institute, 2016; Kormos et al., 2003). Green surfaces indicate closed canopy forests (CCF). Dots indicate camera trap locations (2012–2016) with (yellow and red) and without (black) chimpanzee events.

Article: Aebischer, T., Siguindo, G., Rochat, E., Arandjelovic, M., Heilman, A., Hickisch, R., ... & Wegmann, D. (2017). First quantitative survey delineates the distribution of chimpanzees in the Eastern Central African Republic. Biological Conservation, 213, 84-94.
https://doi.org/10.1016/j.biocon.2017.06.031

Learn about the species' way of life: nocturnal, diurnal, crepuscular

Photographic cameras can also provide information on the times of day/night at which species are active, as well as their ecological niches. Indeed, it is not uncommon for two species sharing the same ecological niche to adopt different daily activity patterns to avoid crossing paths (exclusion by direct competition).

We were interested in quantifying the distribution, abundance and behavior of mobile species, and we worked with a Bayesian time-dependent observation model for camera trap data (Tomcat), suited to estimate relative event densities in space and time. The Tomcat model was used on eight sympatrically occurring duiker Cephalophinae species in the savanna - rainforest ecotone in the Central African Republic and show that most species pairs show little overlap.

Figure 4. Co-occurrence in space and time between the duiker species C. dorsalis, C. weynsi and S. grimma in the Aire de Conservation de Chinko. Top row: interactions in space quantified as 1012/logllsjsj() between species 1 and 2. Bottom: posterior mean (solid line) and 90% credible intervals (shades) of temporal activity patterns. The area shaded in gray represents the overlap coefficient ΔT.

Article: Ait Kaci Azzou, S., Singer, L., Aebischer, T., Caduff, M., Wolf, B., & Wegmann, D. (2021). A sparse observation model to quantify species distributions and their overlap in space and time. Ecography, 44(6), 928-940.
https://doi.org/10.1111/ecog.05411