When you hear the word “tiger”, what do you picture? Probably a large, orange cat with black stripes. But what about different types of tigers? What is the difference between a Bengal and Siberian tiger, anyway? Is there even one?
In phylogenetics, or the study of evolutionary relationships between living organisms, a species is defined as a group of living beings that share many characteristics and can produce offspring. A subspecies is a half-step beyond that: it’s a population that is separate and distinct from others, but can still interbreed. In other words, two separate subspecies live in different areas and look different, but are still able to breed together.
So, a tiger is a species of cat, then. But what about tiger subspecies? What are they, and how many are there?
As is so often the case in science, there is no clear-cut answer. The line between species and subspecies, between subspecies and population, is hazy and indistinct. And when it comes to tigers, there are two main schools of thought regarding the number of subspecies: that there are two, or that there are nine. Scientists used to think there were nine subspecies. But since 2017, the International Union for Conservation of Nature, or IUCN, has officially recognized only two subspecies. And yet, evidence has since been found suggesting the nine subspecies hypothesis may still be the most accurate.
The two official tiger subspecies are the Continental tiger, which lives on the mainland of Asia, and the Sunda tiger, which lives on the island of Indonesia. Continental tigers include the Bengal, Siberian, Indochinese, and Malayan tiger populations. The only current Sunda tigers are those found in Sumatra.
Continental Tigers
Continental tigers are generally larger than Sunda tigers. In fact, the two largest populations – Siberian and the now-extinct Caspian – are from the mainland. Six of the former nine subspecies make up the Continental subspecies: Bengal, Siberian or Amur, Indochinese, Malayan, South China (which are extinct in the wild) and now-extinct Caspian tigers.
The Bengal tiger is quite possibly the most well-known. They can be found in India, Nepal and Bangladesh, and have the largest population. Another easily recognized type is the Siberian, or Amur, tiger. They are found in the forests of East Russia and North China, and have adapted to the cold, with longer and paler fur than other populations.
Caspian tigers have been considered officially extinct since 2003, although there seems to be some disagreement on whether the last sighting was in 1968 or as recent as 1997. Regardless, loss of habitat played a large role in their extinction, as did bounties in the early 1900s.
Caspian tigers were once known by several names, including the Persian tiger, mazandaran tiger, turan tiger, and Hyrcanian tiger. They lived in the region south of the Caspian Sea, with the largest range of any tiger: from Turkey through Central Asia to northwest China. These tigers preferred to live in deserts close to water sources. With their large size and long, pale fur, they were most closely related to the Siberian population. In fact, there are currently plans to reintroduce tigers to the area.
The South China tiger is now extinct in the wild. They survive only in zoos, and their biggest threat is inbreeding due to a small population. Interestingly, this population is the most closely related to tigers’ ancestors.
Sunda Tigers
While Continental tigers live on the mainland, Sunda tigers are found on the islands of Indonesia. Smaller than their mainland cousins, they are critically endangered. The only population left is the Sumatran tiger – the Bali and Javan populations are, sadly, entirely extinct. Sumatran tigers are small, with a dark coat and very thin stripes. They are threatened by the very factors that drove out the other two Sunda tiger populations: hunting and habitat loss.
Biological science is often not straightforward. There are many questions to which we still do not know the answers, and even more with no easy answer at all. Scientists learn more about the world and its inhabitants every day, and it is our duty to make sure these beautiful creatures are still alive for us to learn from for many more years to come.
Sources
Figure 1: https://earth.org/siberian-tigers-numbers-are-on-the-rise-but-the-climate-crisis-could-change-that/
Figure 2: https://www.worldwildlife.org/species/sunda-tiger
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https://endangeredtigers.org/tiger-species/south-china-tiger/
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*Published by Eryn Meeker on 3/22/2025*