Reintroduction, distribution, population dynamics and conservation of a species formerly extinct in the wild: A review of thirty-five years of successful Milu (Elaphurus davidianus) reintroduction in China

Reintroduction plays a vital role in conservation for many endangered species, however, little long-term information is available on the population dynamics and conservation status. Here we provide a detailed account of the Chinese Milu (Elaphurus davidianus) conservation and reintroduction efforts over the past 35 years, and give updated information on current Milu distribution, population dynamics and conservation status based on long-term monitoring (1985-2020) and a detailed follow-up investigation (2013-2020) in 235 wildlife institutions throughout China. Milu conservation in China comprised three phases: i) establishing ex situ populations and increasing the number of Milu through captive breeding (1985-1992); ii) preparing captive Milu for life in the wild and establishing in situ conservation populations (1993-1997); and iii) reintroduction of Milu into the wild throughout their historic range (1998-ongoing). Currently, there are ca. 9062 Milu (including 2825 wild individuals) distributed across 83 sites with 7380 individuals living at Beijing Milu Park, Jiangsu Dafeng Milu Nature Reserve and Hubei Shishou Milu Nature Reserve. The average birth rates in three sites were all over 0.200, and the average adult mortality rates were below 0.085, resulting in a rapid population growth. We discuss a variety of factors that contributed to ex situ conservation success in the reintroduction of a species formerly extinct in the wild, and highlight past and present challenges of Milu conservation in China. Our results will provide helpful information on conservation and reintroduction for other endangered species around the world.

Automated summary

Reintroduction plays a crucial role in the conservation of endangered species, but long-term data on population dynamics and conservation status are often lacking. The conservation efforts of the Chinese Milu over the past 35 years have resulted in a current population of approximately 9062 individuals, with successful reintroductions and rapid population growth. Challenges in Milu conservation in China persist despite these achievements.