Bird and mammal communities transform without collapsing in response to oil palm replanting

Replanting a tree plantation drastically alters its habitat structure and microclimate, leading to changes in its biodiversity. Nevertheless, we lack an understanding of how the replanting of oil palm plantations - the most prominent oil crop globally - affects mammals and birds, while the amount of area replanted is going to increase exponentially over the next few decades. We therefore studied how the bird and mammal community of an oil palm plantation in Malaysian Borneo changed in response to replanting. Using camera traps for mammals, and acoustic recordings and BirdNet for birds, we show that both communities are transformed. Mammal species richness slightly dropped, because of the absence from replanted plantations of, long- and pig-tailed macaques (Macaca fascicularis and M.nemestrina), both endangered primate species. Bird species richness did not significantly differ between replanted and mature plantations. However, the detection frequency of most species changed, as the bird community shifted from forest and woodland species towards open-habitat species. The detection frequency and species richness of different trophic niches stayed largely constant, indicating that birds will still be able to perform similar high-level ecological functions in replanted plantations. Overall, our results show that replanting reshaped mammal and bird communities, but that their diversity and abundance does not collapse. These findings stress the importance of staggered replanting, as opposed to replanting large stretches of plantation in one go, to bolster landscape level biodiversity, and underscore that tree plantations are temporally dynamic habitats.