Today is Endangered Species Day, and new research shows that conservation decisions based on population counts may fail to protect Asian elephants and other large animals.
The new study is published in Frontiers in Ecology and Evolution. It suggests that for endangered species which are large and slow-breeding, such as Asian elephants, conservation decisions should be based on a combination of key vital rates governing population growth instead of short term population size and distribution trends.
Conservation efforts for endangered species
The lead author Dr. Shermin de Silva, who is also President & Founder of the Asian elephant conservation charity Trunks & Leaves, explained:”Critical thresholds in so-called vital rates – such as mortality and fertility rates among males and females of various ages – can signal an approaching population collapse long before numbers drop below a point of no return. We propose that conservation efforts for Asian elephants and other slow-breeding megafauna be aimed at maintaining their ‘demographic safe space’: that is, the combination of key vital rates that supports a non-negative growth rate.”
The case study of Asian elephants
The group applied the ‘demographic safe space’ concept to the case of the Asian elephant.
De Silva added: “Asian elephants are classified as ‘Endangered’ under the IUCN Red List because populations are thought to have declined by at least 50% in less than a century. There are fewer than 50,000 wild Asian elephants living today.”
Wild Asian elephants breed very slowly. The majority of them produce approximately just one calf in six years. The team used mathematical modelling to find out the near-optimal reproduction and high calf survival is necessary to maintain non-negative population growth. The study results show a clear conservation priority for Asian elephants.
De Silva points out: “While the attention of the world has been focused on the ivory trade, for critically endangered Asian elephant populations the greatest threat is habitat loss – followed by illegal trade in live animals and parts. Habitat loss can create something known as ‘extinction debt’ by slowing down birth rates and increasing mortality rates. For slow breeding long-lived species, even incremental changes make a big difference, but their longevity can obscure the risk of extinction.”