Mangareva

I just got back last night from a week-long trip to Mangareva with my friend Rava. This was the most frustrating and unsuccessful fieldwork I have ever done. Mangareva is an ecological disaster; like more famous Easter Island, it was all but deforested by its ancient Polynesian inhabitants, who lost the ability to build ocean-going canoes and sank into a state of intra-island warfare.

For biologists, Mangareva is of particular interest because it is the last of the high islands remaining in the Tuamotus--all the rest of the high islands in this chain eroded into the sea millions of years ago and only atolls remain. The Gambier Archipelago is the name of the cluster of small, rocky islands (of which Mangareva is the largest), situated in a single large lagoon at the southeast end of the Tuamotus, at the edge of the tropics. The flora and fauna of Mangareva would thus be of enormous interest to Pacific biologists, as it could be all that is left of the biota of this ancient chain of islands in the South Pacific. Unfortunately, the colonization of Mangareva by humans a thousand years ago led to the destruction of all the forest--with the exception of a patch of native trees growing on a talus slope at the base of Mt. Mokoto, the second highest mountain on the island. It was to this forest that Rava and I went to look for both cheese trees (Glochidion) and their moths--which were reported from there in the 1930's--and to collect whatever native insects had not gone extinct already for the French Polynesia Terrestrial Arthropod Survey run out of UC Berkeley. We had even located the native forest on Google Earth. We were very excited.

To make a long story short, the "native forest" that was a different color on Google Earth turned out to be a forest of candlenut (Aleurites), a Polynesian-introduced tree, that was being invaded by Melia azedarach (a European-introduced tree), and had an understory of Miscanthus grass--a sort of invasive cane with razor-like leaves--and coffee (yes, coffee). In the midst of this were occasional native shrubs, such as Jossinia (Myrtaceae) and a single, sad, Sophora sapling (Fabaceae). After two days of searching, we found the closest thing to native forest that we ever saw--about half a dozen small Glochidion saplings growing in the understory of a hibiscus thicket along a river. They had no fruits, so I didn't get any Epicephala moths for my thesis research. Nor did these trees show any sign of herbivory from leaf-mining moths--and the specimens from the 1934 Mangarevan Expedition are totally chewed up by leaf-miners, which are ubiquitous elsewhere in Polynesia. Probably, they are extinct.

We had a number of minor adventures, including Rava falling two meters off a ridge when we were trying to get off a mountain and a long, epic struggle to find a way to withdraw cash on the island (it turns out there is a general store that could read my credit card, but this was only good if they actually had any cash in the cash register). We spent two days on a tip from an amateur botanist colleague, Walter, bushwhacking through Miscanthus grass to try to find Glochidion trees of a different species growing at Taku, on the northern end of the island. We ended up in the island "bar", a general store that sells beer but requires customers to consume it indoors so that the bottles can be recycled--the woman at the cash register turned out the next morning to be the choir leader at Catholic Mass. The day of our departure, the municipal boat that transfers people from Mangareva to the airport (on an islet) got stuck when the trailer used to back it into the water broke, and there was a haphazard scramble as everyone tried to get a ride on one of the few boats that was around. The plane then turned up an hour late.

Despite the frustration, Mangareva is a beautiful place--if you don't know anything about plants and don't recognize the barren hillsides and the planted forests of pine and Java plum as an ecological abomination. It is also the jumping-off point for voyages to Pitcairn. I ended up not going to Pitcairn as previously planned because the boat turned out to be full. When we arrived on Mangareva, the Braveheart, the vessel charted to do supply runs, was anchored in the harbor, having just returned from the trip I had hoped to be on.