Monday, August 19, 2013

Manu - Thursday 15 August 2013

Manu is the word for bird in Rapa Nui, just as is it in Maori. Prior to Polynesian arrival, Rapa Nui appears to have hosted a huge population of nesting seabirds since the volcano first emerged millions of years ago. For Polynesians, the nesting sites meant easy prey, so the nutrient inputs from guano died away with the birds.

So far, our soil N isotope results show that the N derived from seabird guano has persisted in agricultural soils more than I would have expected. We also planned to use the steroid signature of seabird guano to identify the time in our cores and soils when humans occupied the landscape. But the published signature of seabirds from North America and Australia hasn't matched what we're seeing in steroid samples run so far. Today, we're getting samples to help us establish a steroid and N isotope signature for seabirds.

We're getting some local guano from Rapa Nui. The frigate bird is typical of the seabirds that would have been present, so we sampled a number of individual guano piles beneath perches.

Sonia arranged for Sebastian Yancovic Pakarati, a Rapa Nui who has recently returned to the island to run an ecotourism business and starting a bird conservation project (The Manu Project), to take us to good site. The site is easier for us to get to than smaller islands with nesting sites. The trip was also very enjoyable because we went to the one part of the island where we haven't had a chance to go - Poike, the oldest and most eroded volcano. Sebastian, with his previous experience as a mountaineering guide in Patagonia, proved excellent at knowing a safe way to descend the sea cliff to frigate bird's spectacular perching sites.

Thanks Sebastian!

Sebastian Yancovic Pakarati, atop the sea cliff we descended to access perching sites.
Sebastian helps collect guano from a spectacular site.
We collected from a number of individual piles of guano beneath perches - hopefully provided a range of independent samples.

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