Natural History of Sri Lanka
The country’s Buddhist heritage and traditions have led to a reverence for all life, which has paid huge dividends for the protection of Sri Lanka’s natural heritage. Almost 25% of the country enjoys protection as reserve forests, reserves, national parks or strict nature reserves. This remarkable percentage is only topped in Asia by Bhutan.
The wide variety of terrestrial habitats to be found here include grasslands, wetlands, scrub forests, mangrove swamps, tropical rain forests and mountain cloud forests. These are in addition to vast coastal and marine areas. This extraordinary habitat diversity supports 492 bird species, over 90 terrestrial mammals, 28 marine mammals, 4,000 flowering plants, more than 100 amphibians and at least 200 species of reptiles. Five of the world’s seven sea turtle species breed on Sri Lanka’s beaches. This amount of species richness is remarkable on an island the size of West Virginia.
ENDEMISM IN SRI LANKAOne of the things that makes Sri Lanka so exciting to visit is that it can still be considered a “new” destination, despite centuries of international visitors and prehistoric settlements dating back 125,000 years. While the human history here is well-documented, there has been remarkably little research done on the flora and fauna of the country, so new species are being discovered regularly. Any hike into a thick section of forest or walk to a secluded cove could uncover a species not yet described by science.
Sri Lanka is recognized as a biodiversity hotspot, with high levels of endemism (species that exist nowhere else). Just in the last 25 years, over 20 new species of freshwater fish, 25 reptiles, 40 freshwater crabs, 55 amphibians, a couple of mammals and three new bird species have been discovered, all of which are endemic to Sri Lanka.
Even the larger mammals with ranges reaching beyond the island have developed unique subspecies on Sri Lanka. Also, to be clear, an island as small as Sri Lanka is not supposed to have large mammals. This country is an anomaly by the rules of island biogeography. It seems that Sri Lanka has had a fortuitous combination of periods of isolation interspersed with periods of connection to larger landmasses. This has allowed animals to get onto the island, but then to be forced to evolve once the connection is cut off by rising seas.
The largest gathering of Asian elephants to be found anywhere is in Sri Lanka. They are larger and darker than the elephants in the rest of Asia. Perhaps their most distinctive characteristic is that many Sri Lankan elephants do not have tusks. Ivory from Sri Lanka made its way to the Roman Empire as far back as two thousand years ago, and the trade continued for centuries. It is likely that the genes for large tusks have been suppressed by hunting. We are seeing this same trend in some regions in Africa as the big “tuskers” get more and more rare. The government of Sri Lanka takes its role as protector of the remaining elephants very seriously and killing an elephant today can result in the death penalty.
The leopard is another widespread species that has taken on a distinct form here. As Sri Lanka’s only large mammalian predator, the leopards here have been able to become more active during the day, and they spend less time in trees than leopards elsewhere. They are also larger than other leopard subspecies, perhaps another result of a lack of competition within their habitats. With fewer than 1,000 remaining, this subspecies is listed as endangered.
Even in the oceans the uniqueness of Sri Lanka stands out. The that are resident off the southern coast of the island have a dialect that is distinct from that “spoken” by the blue whales near Australia. This is despite the fact that there is no obvious reason for them to be isolated from other blue whale populations. For terrestrial animals on an island, it is clear that the surrounding water creates a barrier preventing movement to other places. But what keeps a blue whale from roaming freely in the oceans?
Sri Lanka is a fascinating realm that we are just beginning to understand. With so much unique wildlife, it is critical that Sri Lanka’s biodiversity be protected. If these species disappear from here, they are gone forever. But how did they get here in the first place?
RAMA’S BRIDGESri Lanka is geographically part of the Indian Subcontinent. Once part of the great southern landmass Gondwanaland, it split from Africa sometime between 100 million and 180 million years ago and drifted northward to join Eurasia. That impact 50 million years ago created the Himalaya Range. Many of the earliest species on Sri Lanka probably originated from this deep geological time. However, there have been more recent opportunities for animals to travel from mainland India to the island of Sri Lanka.
Six hundred years ago, you could walk from India to Sri Lanka on foot. A chain of barely-submerged shoals connected the landmasses until a cyclone deepened the channel in the 1400s. During the ice ages approximately 11,000 and 37,000 years ago, you could walk those thirty miles without even getting your feet wet due to lower sea levels.
This bridge likely allowed new species to cross over from India thousands of years ago, after which they began evolving into new subspecies once the island became cut off by the waters of the Palk Strait. In addition to the significant impact this bridge had on the natural history of the island, it plays an equally important role culturally.
Adam’s Bridge or, more appropriately, Rama’s Bridge, appears in the 2,000-year-old Hindu epic story, The Ramayana. In this story, the demon king Ravana captured Rama’s wife Sita and imprisoned her on the island called Lanka. Rama asked Hanuman, the monkey god, to build a bridge to the island with the help of his army. The monkey horde built a passageway out of stone and Rama was able to cross to the island and rescue his wife.
To this day, there is debate about whether Rama’s Bridge is a natural formation, or evidence of these events chronicled in The Ramayana. While it would be easy to think that finding the answer has only an obscure academic or religious significance, the implications actually reach into the very modern worlds of international trade and wildlife conservation.
Commercial shipping interests have long tried to convince the governments of India and Sri Lanka to blast a deep channel through the passageway to cut hundreds of miles off the current route around the southern tip of the island. This could also benefit the blue whales that are often the victims of collisions with ships as they cross the shipping lanes but could have unknown environmental consequences.
Hindu-aligned political parties have always blocked these efforts due to what they see as the sacred nature of Rama’s Bridge. There has even been resistance towards underwater archaeological excavations of the shoal which could make a final determination about the origin of the bridge. Some things are possibly best left to the realm of mystery.