Habitat sharing and interspecies interactions in caves used by bats in the Republic of Congo

Abstract

Bats play key roles in ecosystem functions and provide services to human populations. There is a need to protect bat populations and to mitigate the risks associated with pathogen spillover. Caves are key habitats for many bat species, which use them as roosting and breeding sites. Caves, bats and their guano also attract many other animals along trophic chains which might favor direct or indirect interspecies interactions. Two caves hosting colonies of insectivorous bats have been investigated in the Republic of Congo to characterize habitat sharing and interactions between bats, humans and animals. We set up a camera-trap monitoring protocol during 19 months at the entrance of and inside each cave. Our results demonstrated the richness and complexity of the species interactions around and within these caves. We identified and/or quantified mainly rodents, but also numerous categories of animals such as insects, birds, reptiles and carnivores using the caves. We investigated the temporal variation in the use of caves and the potential interactions between humans, wild animals and bat colonies. Our study contributes to the understanding of the interface and interactions, for the first time quantified, between cave-dwelling animal species, including humans. This knowledge is important to promote the conservation of cave ecosystems and better understand the ecology of infectious diseases.

Keywords: African bats; Bridge host; Camera-trap; Disease ecology; Human-wildlife interface.

Figure 1. Map showing the location of the two caves in our study in the Republic of Congo.

Mont Belo cave is inside the Bouenza department and Boundou cave inside the Niari department. (Map Background Stadia Outdoors). Both caves located about 50 km from each other. Map credit: Leaflet | © OpenStreetMap contributors, CC BY SA © Stadia Maps, © OpenStreetMap Tiles © OpenStreetMap contributors.

Figure 2. Number of days the camera traps were in operation during the study.

A total of nine cameras for all sites, with five for Boundou cave (including one inside the cave) and four for Mont Belo cave (including two inside the cave).

Figure 3. Number of detections per camera day multiplied by 100 according to seasons and grouped by taxonomic class (bird, mammal, reptile and insect class) in (A) Mont Belo cave and (B) Boundou cave.

(A) Mont Belo cave, (B) Boundou cave. (N total = 11,581 detections with 8,422 mammals; 2,899 insects; 79 birds and 45 reptiles).

Figure 4. Accumulation curves of species richness depending on study location.

(Mont Belo outside and inside, Boundou outside and outside) with confidence interval at 95%.

Figure 5. Number of vertebrate species per camera days multiplied by 100 according to study sites (Boundou and Mont Belo cave) and position of camera (inside or outside).

Only the largest numbers of detections are shown in this figure (refer to the Appendix S6 to see all the detections).

Figure 6. Characterization of vertebrate behavior.

(Excluding humans, insects and bats) inside Mont Belo cave and Boundou cave.

Figure 7. Description of human activities.

In (A) Mont Belo cave and (B) Boundou cave. Note the different scale on number of detections by camera days between (A) and (B).

Figure 8. Density of individuals in all study sites depending on time with (A) Activity overlap between genet and bats, (B) activity overlap between flying insects and bats, (C) activity overlap between other insects and small rodents and (D) activity overlap between bats and small rodents.

Figure 9. Daily activity pattern of humans according to activities outside or inside the Mont Belo cave.

(A, B) Hunting activities outside and inside the cave, (C) Guano collection activities outside the cave, (D, E) Prayer activities outside and inside the cave, and (F, G) other activities outside and inside cave.