The purpose of the Saint Niarchos Expedition was to survey reptiles in the Indian Ocean.
It's important to undertake a survey like this for a number of reasons. The first is
just having an accurate, current information on where species occur,
our distribution of biodiversity,
and that's particularly critical in terms of preventing future extinctions.
So once you know
what's out there to protect, you can then make smart decisions about where you
put your limited resources
The second thing is by collecting new information,
observations, genetic samples.
This actually allows us to then
understand better about the evolutionary history of these organisms. It also
allows us to ask sort of interesting questions about how this region
developed and evolved in this relatively remote area of the Indian Ocean.
I really wanted to focus on three different island systems.
And the first islands were the Seychelles,
which are found north of Madagascar.
One of the more poorly known reptiles in the Seychelles is
the chameleon, which occurs there. The first chameleon specimens that were collected
from the Seychelles were described as two separate species.
But for the last almost two hundred years, they've always been assumed to
be a single species. We now know from the genetic data that they are, in fact, two species.
So essentially
these first descriptions made two hundred years ago were actually correct. So
the _____ survey was really designed to
take us to the critical islands, really nailing down the distribution of these
two species. I was immediately joining an experienced team of people
that I had worked with previously, who were
fantastic at catching chameleons.
What we actually did was
then visit a series of islands that we'd identified were
key priorities.
The first of those islands was Silhouette Island.
What we were doing is intensively at night going out looking for chameleons.
In the case of Silhouette, what was really fun about it was that the chameleons were there.
They were actually healthy populations
and I think over the course of three nights, we recorded in the order of thirty to
forty animals.
So after around
Silhouette, we then took on the high-risk part of the
expedition, which was to survey the islands where chameleons had never been
found before or where there were museum records that
were very old. Sadly we didn't find any populations. One of the things about biodiversity
is that surface area is a good predictor of a species' richness.
In the case of islands, the smaller the island gets, the fewer species it has.
In the case of the Seychelles and the chameleons, this is sort of the typical pattern we
are seeing here.
The second expedition
to the Mascarene Islands. This really interesting volcanic system,
which were formed from an ancient hot spot.
The oldest island is Rodrigues and that the youngest is La Reunion. And I was
surveying both
those areas for reptiles.
Once we got to Rodrigues, the intensity of the survey immediately kicked in and we spent the
the next twelve days surveying
mainly Rodrigues and these off-shore islets. It's really been
transformed since humans arrived there around the seventeen hundreds. The first
people who settled started clearing vegetation
and species.
There have been surveys done in Rodrigues, but not all the rocky islets and islands
have been surveyed, and
even on the mainland there's some uncertainty. For example, there were geckos
on Rodrigues, which have never been seen in terms of living animals.
The best place to look for those were in the bottom of these steep canyons,
which would have never been cleared for cultivation. We were also surveying rocky
outcrops in the hope that we might find some rock-adapted geckos. During
the day it's walking through forests, scanning, and looking for movements.
The fine things like skinks we put in these pitfall traps, and we also, at night, go out
with headlamps
and look for animals that are active at night, which is particularly important for
seeing species that are otherwise you could very easily overlook.
There were four house geckos that we commonly came across, but
what we actually
found that was sort of interesting was that each of these islands seem to have its own unique
complement of different species. In the case of one of these house geckos
_______, we actually found some interesting size differences
between different island populations, which suggests that since
the time that they actually reached these islands there's already been some local adaptation.
It gives us an opportunity to actually see a new cycle of evolution starting. During La Reunion,
we did five surveys starting
from sea level all the way up to about fourteen hundred meters.
And a higher elevation has very little reptile diversity.
The amphibians are restricted to just these introduced toads, which are pretty much found everywhere in Reunion.
It still has an active volcano on it and
you really get the sense that through this volcanic activity that
if there were a species
formerly evolved there they would have gone extinct.
Many of the forests that we surveyed in Reunion looked just absolutely beautiful,
but they were sort of eerily quiet.
I remember being at one site at six hundred meters and putting down a half-eaten tin of
corned beef,
and I forgot about it about six hours later, and I came back.
Not a single insect on it. It was still sitting there completely untouched and uneaten.
We found introduced species
and once we hit the coast of _____ we were
surveying, we found things like the _____
_____ gecko on the island,
but we were hoping we'd find skinks or these _____ day geckos.
We didn't find any populations. The surveys really provided a lot
more information now about what the situation is for these different islands.
That has important implications for conserving those species and of course
allows us to then think about moving onto the next step.