Traditional ecological knowledge for great ape conservation in Gabon

Abstract

Background: Traditional ecological knowledge (TEK) held by Indigenous communities is increasingly recognised as a cost effective, locally adapted complement to instrument-based wildlife monitoring. In southern Gabon, hunter trackers routinely distinguish chimpanzee Pan troglodytes troglodytes and western lowland gorilla Gorilla gorilla gorilla faeces in the field, yet the reliability of these identifications has never been rigorously tested.

Methods: Twenty-two experienced Indigenous participants guided systematic surveys across ~ 10 000 ha of unprotected forest near Makatamangoy and Tébé. For every faecal sample encountered, collaborators reached a consensual species identification using their customary criteria (colour, odour, texture, composition, quantity, associated footprints, vegetation disturbance). Samples (n = 637) were preserved in RNAlater^® and later assigned to species by 12S rRNA mitochondrial sequencing. Agreement between Indigenous and molecular identifications was summarised in a confusion matrix; accuracy, sensitivity, specificity, predictive values and Cohen's κ were calculated. The prevalence of each empirical criterion was expressed as the proportion of interviewees citing it, and species differences were tested with Fisher's exact tests (α = 0.05).

Results: Indigenous knowledge correctly identified 633 of 637 samples (overall accuracy = 99.37%; κ = 0.987, p < 0.001). Sensitivity was 99.1% for chimpanzee and 99.0% for gorilla, while specificity exceeded 99.6% for both species. Seven primary criteria underpinned identifications; colour (100%) and odour (86.4%) were most frequently evoked. Twelve of 24 sub-criteria differed significantly between species. Chimpanzee faeces were more often described as brown-yellow, soft and abundant with faint heelprints, whereas gorilla faeces were typically black, fibrous, hard and accompanied by pronounced heel and fist prints plus flattened vegetation.

Conclusion: Indigenous trackers in Gabon demonstrate near-perfect accuracy in differentiating great ape faeces, validating TEK as a robust, low-cost tool for primate monitoring. Integrating this expertise into participatory conservation programmes could expand surveillance outside protected areas, enhance early detection of demographic or health changes, and strengthen community stewardship of threatened ape populations.

Keywords: Chimpanzee; Conservation strategies; Gabon; Gorilla; Great apes; Traditional ecological knowledge.

Fig. 1

Study site mapping. A Chimpanzee in its natural habitat; B Gorilla in its natural habitat; C Aerial view of the forest; D Map of Gabon highlighting the Haut-Ogooué Province; E Map of the Haut-Ogooué Province; F Zoomed-in view of the Makatamangoy forest

Fig. 2

General criteria used to identify great ape feces

Fig. 3

Frequency of criteria used for species-specific identification of great ape feces. (Legend: Liquid_Texture: Fluid and without a defined shape; Pasty_Texture: Neither firm nor liquid, with a paste-like consistency; Soft_Texture: soft but well-formed; Hard_Texture: Firm and compact; Mixed_Vegetal_Content: Includes both plant fibers and undigested fragments of fruits and seeds; Varied_Composition: Composed of various plant residues such as fruits and leaves, and occasionally includes traces of animal protein, such as hairs or insect fragments; High_Fiber_content: Often contains undigested plant fiber from leaves, stems, and fruits)

Fig. 4

Comparative use of empirical criteria to identify Chimpanzee and Gorilla feces. Each bar represents the difference in frequency of mention for a given empirical criterion between chimpanzee and gorilla feces, as reported by Indigenous participants. Positive values indicate criteria more frequently cited for chimpanzees, while negative values reflect those more commonly associated with gorillas. Criteria in red are statistically significant (p < 0.05) and may serve as discriminating features between the two species