Mauritius: Invaders in Paradise

Before and After: Path northward from Gri gri Beach, Souillac, left, and, right, a sugar cane field near Trois Boutiques, south of Mahebourg. Actually, the view on the right is one I saw several places in this island. This crop is sadly ubiquitous throughout the country. The one on the left required a bit of hiking to get to. And if you look carefully, even in this picture on the left, biodiverse degradation is also visible, starting with the “pine” trees, Beach Sheoak, Casuarina equisetifolia.

It is hard now to imagine what this island was like centuries before. It must have been really beautiful at one time. Mark Twain wrote,

“What there is of Mauritius is beautiful. You have undulating wide expanses of sugar-cane—a fine, fresh green and very pleasant to the eye; and everywhere else you have a ragged luxuriance of tropic vegetation of vivid greens of varying shades, a wild tangle of underbrush, with graceful tall palms lifting their crippled plumes high above it; and you have stretches of shady dense forest with limpid streams frolicking through them…” – Following the Equator, 1896

In more recent times new invaders have made this island noticeably less beautiful and, more to the point, less biodiverse. Some of these invaders are themselves beautiful to look at, but what they are doing to the island is not.

Main Avian Invaders: The Feathery Five:
When we see a bird here in Mauritius there is a 95% chance it will be one of these five. What do these birds have in common? They are all invasive, having pushed out, or in the process of pushing out other species. Biodiversity on this island has taken a major hit. Here are those bad boys. Clockwise from top left:

Common Myna, Acridotheres tristis. Aside from pushing out other birds these birds act like little “Johnny Appleseeds”, introducing other trees and plants that have no business being here. The Mynah, for instance, loves the fruit of the Strangler Fig (Banyan) and, well, “plants” the seeds wherever it flies.

Red-whiskered Bulbul, Pycnonotus jocosus

Zebra Dove, Geopelia striata. These first three birds all came from various regions of Asia.

Village Weaver, Ploceus cucullatus, from Africa mainland

Red fody, Foudia madagascariensis, from – you guessed it – Madagascar.

Other invasive species, not birds, have also given the island an ecological drubbing. Here are four for dishonorable mention:

Small Indian Mongoose, Urva auropunctata, brought over from India to bring the rat population down. The rats had swelled in number when the island was given over to Sugar Cane cultivation. Well, the Mongoose did a middling job on those rodents – and also on native birds. Oops.

Guttural Toad, Sclerophrys gutturalis

Madagascar Giant Day Gecko, Phelsuma grandis, from nearby Madagascar, very aggressive toward native reptiles. But, like a lot of these invaders, very photogenic. So … there is that.

This Asian House Shrew, Suncus murinus, wouldn’t stay long enough for a decent photo. He’s on a quest for insects and animals, some larger than him. He is the cause of the 2011 extinction of the Orange-tailed Skink, Austroablepharus naranjicauda on Flat Island, located off the north coast of Mauritius. The skinks, endemic to that little island, were no match for the shrew, which inadvertently came over with a lumber shipment. The skinks, in only fifteen months, went from thousands to zero. Fortunately zoologists were able to rescue some and relocate them to two nearby uninhabited – and unshrewed! – islands. Fingers crossed.