Data from: Rewilding in Southeast Asia: Singapore as a case study

Re-establishing extirpated wildlife – or ‘rewilding’ – is touted as a way
to restore biodiversity and ecosystem processes, but we lack real-world
examples of this process, particularly in Southeast Asia. Here we use a
decade of aggregated camera trap data, N-mixture occupancy models, and
input from local wildlife experts to describe the unassisted
recolonization of two native large herbivores in Singapore. Sambar deer
(Rusa unicolor) escaped from captivity (private or public zoos) in the
1970s and contemporary camera trap data show they have only colonized
nearby forest fragments and their abundance remains low. Wild pigs (Sus
scrofa), in contrast, naturally recolonized by swimming from Malaysia in
the 1990s and have rapidly expanded their range and abundance across
Singapore. While wild pigs have not recolonized all viable green spaces
yet, their trajectory indicates they soon will. We also note that a third
ungulate, the muntjac deer (Muntiacus muntjak), was captured in camera
trapping in 2014 and 2015 but was never recorded afterward despite
increased sampling effort, and thus we do not focus on their presumably
unsuccessful recolonization. The divergent rewilding trajectories between
sambar deer and wild pigs suggest different conservation outcomes and
management requirements. Sambar deer may restore lost plant-animal
interactions such as herbivory and seed dispersal without requiring
significant management. Wild pigs, in contrast, have reached high numbers
rapidly and may require active management to avoid hyperabundance and
negative ecological impacts in regions such as Singapore that lack both
hunting and large predators.