Capturing the Diversity – Where The Atlantic comes ashore

The next stage was to traverses one of these lava flows.  I was getting used to crossing these but this one was remarkable.  We had to climb a considerable way to get up on top of it – obviously it had been a thick coating of molten rock which had come down the mountainside at some stage.  It was relatively thin, but as I paused atop it, and looked first up and down, I was astonished to see it looked black in one direction and white in the other.  The lava field had been used as a nesting colony for hundreds, maybe thousands of years, but the birds sheltered on the uphill side of the outcrops of rock, giving them some shelter from the punishing south easterly winds.  So as you looked down, you saw all the guano from the ghost colony, looking uphill all the guano was hidden and you saw the true colour of the rock.

We were trying to make our way to South East Bay now, but again the most direct route was not the easiest, and we instead started heading north west.  I could see how much we had descended from our starting point.  I could not see the NASA site, but you could see the massive lump of earth that it sat on; and it towered above us.  While we plodded along on the surface , it did cross my mind that whatever more walking we did down here, we still had to somehow climb all the way back up there.

South East Bay is one of the most dramatic places on Ascension Island and can only really be seen in its true glory from the top of the cliffs.  From the NASA site, it appears a beautiful collection of coloured rocks and a sweeping bay of frothing water, but only from down here do you get the full impact of just how superlative the terrain is, and how dramatic the full force of the Atlantic Ocean coming into contact with the cliffs really is.

The first thing to strike me was a curious hill on the far side of the bay.  It had a steep white cliff, which had a funny little promontory of white rock sticking out the front.  The white rock was capped by a carpet of lava, this time a deep rusty red colour.  The lava coated the whole backside of a rounded hill.  The effect was to make you think you were looking at a giant white hedgehog with red spines.  It was not a surprise to hear that it was called Wig Hill.  In the centre of the bay, where it more or less turned right angles from the south coast onto the extended peninsula of the Letterbox, another lava flow, another black one, poured down into the sea.  It was obviously  relatively recent and the sea had yet to erode it back to a natural coastline; instead black rocks extended well out into the bay.  But the sea was having a good go.  Massive rolling waves came into the bay at high speed, bashed against the solid rock and sprayed up, some coming higher than the cliffs themselves.  Time after time these waves would crash in, and the spray and froth would fizz and shimmer for many seconds after the undertow had sucked the water back out of the bay.  I certainly would not want to be in a boat down there – you would be smashed to smithereens hundreds of times.  Death would be a mercy.

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Stedson, Simon and Tara monitoring the noddy nests on the cliffside

The main reason for coming to this cliff edge on the western side of the Letterbox was to monitor its noddy colonies.  I was still feeling a bit tender on my ribs, and I had already seen noddy nests, so I volunteered to look after their bags while Simon, Tara and Stedson went down in amongst the nests.  I got another sense of vertigo as I looked down.  Tara said – once you are down there it is not so bad, but I watched those big waves crashing below us, and did not want to chance having more mishaps.  So for about ten minutes I just sat there mesmerized by the strength and beauty of the ocean as it came ashore.

Capturing the Diversity – How to monitor the bird nests

It took quite a while before we reached the first birds and they were situated on the first of a series of small stacks along the coast.  Again it was impossible to count every egg and chick, but they monitor using binoculars and count the adult birds.  But nearby, we started coming in to contact with the first birds who were nesting on the mainland.  The species here are black and brown noddies, some boobies and a few tropic birds.  Counting the noddy nests was a bit precarious as they do prefer cliffside perches, but the others tended to nest on the flatter ground.  To be accurate that the right nests are being properly monitored, numbered metal pegs were left at the nest site.  A database had been created by RSPB  that allowed the team to print out the records for the walk they were doing.  This would tell them where there were existing nests (with the numbers of the pegs they left there) that needed to be monitored again.  The job was to find these nests again; usually the team could remember roughly where they were but they also had the GPS coordinates in case they needed guidance.  The tags  meant that you could keep track of which nest you were looking at and work out the sequence.  Then they just had to update the sheet with the new status (number of eggs, chicks, fledglings or abandoned nests).  If the nest is empty the peg is removed, cleaned and used again somewhere else.  This did sometimes cause some problems for the database as peg numbers could get confused and give the wrong data on the printed out monitoring sheets.  One of my jobs was to clean up the mess in the database and help make the system more foolproof.  If a new nest was spotted on the walk then more details had to be captured; the location and the species of bird as well as the nesting status.  And the new peg number.

It was all rather complicated but did help to calculate the nesting success of different species.  It took some time for Edsel and myself to get our heads around how this could be used in GIS.  Yes, we could show the current status of nesting on the islands, but what was more important was that we needed to help them show where some species were getting more successes than failures, and any progression of nesting further and further on to the mainland or in new locations around the coast. Fortunately, the way the database was set up, you could slice and dice it whichever way you wanted, an Edsel had written a canny programme to automatically draw the results of these filters and label them uniquely.  In this way, monthly maps of nest status could be shown, different coloured dots for different species and the labels showing the status, and another map could show in a period how many nesting successes and failures there had been in each area.  Tara, when she did her studies quite successfully showed how the birds were gaining in their nesting confidence and moving further and further away from those refuge stacks they had once relied on to maintain the populations in the islands.