•A newly published study suggests that conservation efforts for the Asian elephant should consider indicators other than population count.
•Population size and distribution statistics may fail to show a species‘ impending collapse in time for it to be prevented.
•Thus, monitoring fertility and mortality rates across sexes and ages could be more effective at gauging species viability.


In less than 100 years, the global Asian elephant (Elephas maximus) population has diminished by more than 50 percent.

From over 100,000 at the start of the 20th century, there are now fewer than 50,000 Asian elephants in the wild. It’s a frighteningly sharp decline–one that happened over the course of just 60 to 75 years. Unsurprisingly, it was enough for the International Union for Conservation of Nature (IUCN) to classify the species as Endangered.

There are numerous reasons why the largest living land animal in Asia is inching closer to extinction. Asian elephants have lost around 85% of their natural habitat, largely due to human expansion. In addition, farmers kill the animals to prevent them from raiding and trampling on their crops. Animal trafficking is another threat to the species. Meanwhile, ivory poaching is less of a problem for Asian elephants than their African cousins; only a few males (and almost no females) of the species have tusks.

Despite current efforts to prevent the Asian elephant from getting wiped out, the species’ population continues to dwindle. A new study from the Smithsonian Conservation Biology Institute suggests that it may be because we’ve been paying too much attention to the wrong numbers.

The elephant in the room?

“[W]hile 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,” says biologist Dr. Shermin de Silva, lead author of the study.

According to de Silva, founder of Asian elephant conservation charity Trunks & Leaves, monitoring population numbers isn’t enough to save slow-breeding megafauna (such as the Asian elephant and other large animal species) from extinction.

“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.”

The biologist added that vital rates could reveal an impending 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.”

Saving endangered megafauna such as the Indian elephant (Elephas maximus indicus) may require monitoring their demographic safe space. (Photo: Dipankar Ghose/World Wildlife Fund-India)

Math, mothers, and mammoths

The researchers used mathematical modeling to examine the Asian elephant’s demographic safe space. By their calculations, the annual female mortality rate needs to be kept under 7.5 percent. Ideally, adult mortality should be as low as 3 percent per year for the species to endure both its slow birth rate and a high annual calf mortality rate (up to one-third of calves below 3 years of age).

As de Silva and co-author Peter Leimgruber concluded: “Measures to enhance survival of calves, and particularly females, are key to saving the Asian elephant.”

The researchers acknowledge that their study does have limitations. Chief among these is the fact that there’s simply not enough data to work with at the moment. However, de Silva argues that historical evidence does support this, in a mammoth way.

“Genomic studies of the last mammoths isolated on Wrangel Island — between Russia and Alaska — have shown that although they were able to persist for thousands of years beyond the extinction of mainland populations with just ~300 individuals, they had accumulated numerous genetic mutations that may have eventually contributed to their extinction,” explains de Silva.

Basing conservation decisions on population counts may not be enough to save slow-breeding megafauna from extinction. (Photo: Adobe Stock)

A mega problem for megafauna

The researchers believe that these findings are also applicable for other large, slow-breeding species, such as giraffes and rhinos. Thus, de Silva and Leimgruber emphasize the need to collect more demographic data on these species in the wild.

“Rather than rely on simple population counts or estimates of near-term extinction probability, we urge that conservation resources for slow-breeding megafauna also be invested in identifying demographic tipping points and how to maintain populations within their safe spaces,” says de Silva.


Cover photo: Dipankar Ghose/WWF-India

References

  • https://www.bbc.co.uk/newsround/45032922
  • https://www.frontiersin.org/articles/10.3389/fevo.2019.00171/full
  • https://www.sciencedaily.com/releases2019/05/190517081640.htm
  • https://www.worldwildlife.org/magazine/issues/winter-2018/articles/the-status-of-asian-elephants

Author: Mikael Angelo Francisco

Bitten by the science writing bug, Mikael has years of writing and editorial experience under his belt. As the editor-in-chief of FlipScience, Mikael has sworn to help make science more fun and interesting for geeky readers and casual audiences alike.