African buffalo in focus: population structure, habitat use, and systematic behaviour in Ethiopia (Gambella National Park).

Abstract

Information on African buffalo (Syncerus caffer) population dynamics and resource selection within Ethiopian protected areas remain limited. Grounded in optimal foraging theory and the risk-disturbance hypothesis, this study quantified buffalo population structure, abundance, habitat association, diet, and daytime activity budgets in Gambella National Park. Field monitoring spanned wet and dry seasons from 2022 to 2023. We deployed 35 line transects stratified across four distinct habitat types, processing encounter data through Distance 7.5 software. Spatial logistic regressions, micro-histological faecal analyses, feeding-track inspections, and instantaneous scan sampling were used to evaluate resource choice and behavioural rhythms. Fieldwork yielded 399 independent herd encounters. Population abundance estimates totalled 4,606 ± 3,335 individuals in 2022 and 4,584 ± 3,053 individuals in 2023, while a pooled model estimated 5,602 individuals (mean landscape density: 1.22 individuals/km²). The population showed a female-biased adult sex ratio (0.74:1.00 to 0.98:1.00) and steady calf-to-juvenile recruitment ratios (0.46:1.00 to 0.53:1.00). Seasonal fluctuations significantly shifted habitat selection (χ² (3) = 26.17, p < 0.001); herds crowded into permanent wetlands (~ 31%) and forestlands (26.16%) during dry periods. Logistic regression models indicated that buffalo occurrence correlated positively with forest canopy cover (OR = 1.036-1.038, p < 0.01), decreased with distance from water (p ≤ 0.03), and dropped near human settlements (OR = 0.78, p = 0.01). Diet selection comprised eleven grass species dominated by Urochloa mosambicensis, with no significant seasonal variation (χ² (10) = 4.87, p = 0.898). Diurnal activity budgets remained stable across seasons (χ² (8) = 6.22, p = 0.623), displaying a bimodal feeding pattern that accounted for roughly 30% of daytime activity. Although demographic parameters suggest short-term stability, intense herd compression into shrinking dry season refugia highlights underlying ecological vulnerability. Conservation frameworks must prioritize wetland protection, stricter enforcement of community-managed border buffer zones, and the preservation of transboundary migration corridors.