Leveraging archaeological specimens to investigate failed invasions: A case study on Okhotsk pigs, northern Japan

Abstract

Invasive species pose a major threat to biodiversity, yet our understanding of failed invasions/translocations, instances where alien/introduced species fail to establish, remains limited. Investigating the factors behind failed invasions is critical for improving prevention and management strategies for modern biological invasions. Here, we propose a novel framework that utilizes archaeological archives to uncover evidence of failed invasions. We estimated the biological and ecological factors contributing to the failed invasion of pigs from later prehistory to recent times (299 cal BC to 1900 AD) on Rebun Island in far northern Japan by synthesizing the evidence obtained from stable isotopes, zooarchaeology, and historical documents. Despite the anthropogenic introductions of pigs into Rebun Island, pigs did not establish a feral population and disappeared after ca. 1200 AD. We identified reduced propagule pressure, abiotic resistance due to the cold climate, and decreased resources as the three key factors that contributed to the disappearance of pigs. Pigs are one of the most widespread invasive species globally, and this study represents a novel approach to studying failed invasions using archaeological data, which aligns with the framework of conservation paleobiology.