Elephants as imperfect gardeners: How megafauna reshape, not degrade, rainforest bird communities

Research Highlight: Korejs, K., Hořák, D., Krystof, C., Sedlacek, O., Motombi, F., Ewome, F., Molua, L., Tache, J., Kamga, S., Christopher, J. & Riegert, J. (2026). Megafaunal engineering in the tropical rainforest: African forest elephants (Loxodonta cyclotis) reduce avian species richness but elevate functional diversity. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.70369. Elephants are major ecosystem engineers, but their effects on animal communities may be more complex than expected. A 4-year study on Mount Cameroon found that grazing by African forest elephants (Loxodonta cyclotis) reduced avian species richness to levels comparable with those in forest degraded by human activity. Yet, unlike human-driven degradation, elephant grazing did not promote the replacement of forest-specialist birds by open-habitat generalists. Instead, it shifted communities towards understorey and terrestrial invertivores at the cost of large frugivores. Despite lower species richness, elephant-grazed forests showed higher functional diversity but lower functional redundancy than undisturbed forest, suggesting a change in community composition rather than simple ecological impoverishment. These findings show that the ecological signature of megaherbivore-driven disturbance differs fundamentally from anthropogenic disturbance, and that species richness alone may not adequately capture the ecological role and conservation value of large herbivores.