Modelling the surprising recolonisation of an understudied aquatic mammal in a highly urbanised area: fortune favoured the smooth‐coated otter in Singapore

Abstract

Ever‐growing human activities present an active and continuing threat to many species throughout the world. Nevertheless, concerted conservation efforts in some regions have balanced these threats and allowed endangered species to recolonise former parts of their original ranges and reverse their decline. This is notably the case of the smooth‐coated otter Lutrogale perspicillata. In 1998, individuals returned to Singapore after more than a 20‐year absence. In 2017, 79 otters were counted throughout the heavily urbanized city. Despite this comeback, the future of the species in Singapore is unclear. By collating information on the species' life history traits, we implemented a spatially explicit individual based model with the aim of first replicating the original recolonisation of the species in Singapore and secondly, trying to predict its future population trend. The model demonstrated that successful establishment of Singapore population from the initial immigrants was highly uncertain. In 43% of cases, stochastic extinction occurred. From the 9% of model replicates that closely reproduced the observed colonisation history, projections showed that the population would reach close to 200 individuals in 50 years. This study successfully demonstrates the use of individual‐based modelling to simulate the inherently stochastic recolonisation dynamics of an endangered species and predict its longer‐term future. We discuss emerging issues that may arise from increasing negative interactions between otters and humans and the general challenges associated with rewilding highly urbanized environments. We stress the importance of long‐term monitoring surveys and education campaigns to mitigate human–wildlife conflicts. With species and natural habitats increasingly threatened by our ever‐growing human expansion, understanding the factors that allow human‐dominated landscapes to be compatible with biodiversity is of the utmost importance.