We awoke around 4:30 this morning to the clanking of the anchor being raised. Those of us who were lucky were able to get back to sleep for another couple of hours. After breakfast we arrived at Nelsons Island, the most isolated island here, perched on the northern rim of the Great Chagos Bank.

Nelsons Island was never inhabited. People came from the other atolls only to collect birds, turtles and the eggs, and so for that reason, there are no rats. Instead, there are thousands of birds.

Pete Carr, the expedition ornithologist, was very enthusiastic about getting onto the island to continue his ongoing monitoring of the spectacular bird populations. He was first in line waiting for the RIB to take us ashore. Well, not quite ashore, as it was low tide with fairly rough sea conditions and the island is surrounded by reef. We had to jump into the water and swim 20 metres or so onto the reef and fight our way through the surf into shallow water. But it was worth it.

Pete Carr takes on the story from here:

Tuesday was a non-diving day for the divers and the first visit to an island that was known to be rat-free and categorized as an International Union for the Conservation of Nature (IUCN) Important Bird Area: Nelsons Island. After a challenging swim ashore that involved navigating over the island’s reef fringe, bird research and monitoring was underway.

Nelsons Island is a unique place in the Chagos. Only two species of tree have colonised the island - Pisonia and Coconut - and both appear to have arrived naturally. The vast remainder of the island is covered by the shrubs Scaveola and Argusia. This has brought about the unusual circumstance of red-footed boobies breeding in coconut trees in some numbers - this is the only island in the Chagos where this occurs. (Possibly Nelsons is younger than other islands as other tree species have not yet arrived. So, boobies breed on what is available, offering a view of a Chagos island 10,000 years ago?)

The island remains in excellent health. Lesser noddy breeding numbers are equivalent to what they were in 1996 and both red-footed and brown booby breeding populations are at a record high. This is of particular importance because in the Indian Ocean as a whole, populations of boobies are crashing. Of concern is the fact that the brown noddy has still not been found to be breeding in numbers anywhere near their high of 1996.

Even though the sky was overcast and some precipitation fell, the beautiful endemic subspecies of the Meadow Argus butterfly managed to put in a few brief appearances while we were on the island.

Charles Sheppard wraps up the day’s activities:

After returning to the Pacific Marlin, we sailed to the submerged atoll of Victory Bank, where Tom and Jessica deployed, our BRUV team, several of the stereo video units. A description of that will be in tomorrow’s blog, when they have had time to download the footage

In the evening we continued on to Peros Banhos atoll, where we will be diving for the next three days.

Previously in this series:

Conserving Chagos: Science Expedition to World’s Largest “Ocean Park”

Conserving Chagos: Starting Out

Conserving Chagos: Manta Rays

Conserving Chagos: Last Day around Diego Garcia

Conserving Chagos: Salomons Atoll

Conserving Chagos: Stormy weather

About the Author: Pete Carr, Scientist

In conjunction with the Royal Society for the Protection of Birds, Pete has recently (2011) published “Birds of BIOT” (BIOT stands for British Indian Ocean Territory, the administrative name for the Chagos archipelago), a book that summarises the avifauna of the Territory; he was also the author of the original paper that designated the ten IUCN categorised Important Bird Areas (IBAs) within BIOT. As a member of the Chagos 2010 Scientific Research Expedition he was co-responsible for terrestrial monitoring, focusing on ecological restoration priorities, Odonata distribution as well as seabird censuses. For the past three years he has spearheaded forest and wetland restoration work whilst working on Diego Garcia.