Why Sulawesi Is So Special

By Dr. George Beccaloni

“We now come to the Island of Celebes, in many respects the most remarkable and interesting in the whole region, or perhaps on the globe, since no other island seems to present so many curious problems for solution.” (Alfred Russel Wallace 1876)

This quotation from the great Victorian naturalist and explorer, Alfred Russel Wallace, sums up nicely why SeaTrek has chosen Sulawesi as the main attraction of our new 14-day cruises starting in 2020, for it is a mysterious place filled with species found nowhere else on earth.

Sulawesi is the world’s eleventh-largest island, with an area of 174,600 km2, and wedged in between the continental landmasses of Southeast Asia and Australia, it is the largest island in Wallacea. It is home to an incredible array of flora and fauna that are endemic to the island, and it is this diversity of species from different continents that puzzled Wallace and led to him to remark in his book ‘The Malay Archipelago’ that Sulawesi represented ‘a rather ancient land”, and that it must have had its origin “in a unique antiquity”.

Wallace’s fascination with the island stemmed from at least three reasons. One, because a high proportion of its animals are found nowhere else. For example, 97 of its 230 resident bird species are endemic (restricted to Sulawesi). Two, it has some very distinctive species which are very different from their relatives in other regions, e.g. the curious Babirusa pig, with its upward pointing curled tusks, the tailless Chimp-like Crested Black Macaque, and the peculiar Maleo bird, which buries its eggs in sand like turtles do. The third reason is that it is the furthest west that marsupials are found from their stronghold in Australia and the only place in Asia where they live alongside monkeys. There are two species on Sulawesi, the Bear and Dwarf cuscus, which live in trees and feed mainly on leaves.

Sulawesi’s animals originated from ancestors which got there by flying, swimming or drifting on floating vegetation from surrounding regions. Unlike the islands to its west, which are surrounded by shallow seas and formed part of mainland Asia when sea levels were lower, a deep trench to the west of Sulawesi means it was never connected to Asia. This trench marks the position of the Wallace Line, an invisible boundary between the animals of Asia and Australasia which Wallace discovered during his eight-year expedition to the region in the mid-19th century.

Unlike many of the volcanic islands to its east, Sulawesi is ancient, so there was plenty of time for animals to evolve there in sometimes surprising ways. Some groups have diversified remarkably on the island, such as tarsiers and macaques, which now have 11 and 7 species respectively. Others have evolved into strange forms, such as the recently discovered Hog-nosed Shrew Rat which has “curiously long pubic hair”, lacks molar teeth and lives on a diet of earthworms, and the newly named 5cm-long King Wasp, the males of which have very strange long sickle-shaped jaws.

Wallace visited Sulawesi three times (in 1856, 1857 and 1859) to collect and study animals and he discovered many species new to science there, including the Dwarf Cuscus. His account of how Maleo, Anoa and Babirusa were common in the Batu Putih area in North Sulawesi in his book The Malay Archipelago, was the inspiration for the creation of Tangkoko Nature Reserve there. It is therefore fitting that a huge monument to him was unveiled in Tangkoko in February 2019.