The eradication of rats on McKean Island

The expedition has been going fast and furious and moments to write blog entries are sometimes fleeting. The deck salon and cabins are spaces with the constant motion of people, dive gear, science gear, NAI'A crew in their blue uniforms doing their part in running the ship, and so on. At this moment, Stuart Sandin just walked by with his wetsuit half pulled up and looking for his clipboard. Craig Cook just came to me and said he was about to set up the hyperbaric chamber again for testing; Brian Skerry walks by with two underwater camera housings with strobes, one draped over each arm like leggy spiders. All is going well as we make our way through the Phoenix Islands Protected Area (PIPA).


A dive skiff approaching the Phoenix Islands photographed for the National Geographic article about a previous expedition (Photo: Paul Nicklen)

Yesterday, we stopped for nine hours at McKean Island, the smallest Phoenix Islands; it is no more than a big piece of coral rock rising some two meters out of the heaving swell of the Pacific Ocean with thousands of seabirds circling, screeching and walking around this an outpost for ocean bird life (including red-tailed tropic birds, masked booby, brown booby, red-footed booby, sooty tern, great frigate bird, white-throated storm petrel, Audubon's shearwater, brown noddy, white tern---to name a few!) Not a tree or bush taller than 12 inches anywhere, bird eggs lying on the ground everywhere, very hot, and you can walk around perimeter of island in about an hour.


(Photo: Greg Stone)

There is no "landing site" for a boat on this island, so you have to swim ashore. Rob Barrel drives a skiff in toward the island with Alan Dynner, Larry Madin, Craig Cook, Tukabu Teroroko, and Tuake Teema. We are within 150 feet of shore and Rob says, "this is it boys, you gotta swim from here." Rob understandably does not want the skiff to get caught on the swell and overturned or to hit rocks with his propeller. Craig and Tukabu decide not to go at this stage. Reminds me of when my wife, Austen, did the bird surveys on this island with me nine years ago. A perfect replay.

Like Austen and I did before, Larry, Tuake, Alan and I step off the side of the boat with shoes, hats, shirts, shorts and glasses on and start to kick to shore, all suddenly wishing we had fins on instead of boat shoes. One hand holding my hat and water proof camera bag, the other pawing through the water doing a one armed “dog paddle.” The closer we get to shore the larger the waves and the water remains deep; I keep reaching down with my feet trying to find a solid foot hold the bottom. The water is so clear the coral bottom looks close, but still out of reach.. Then the back surge from the receding waves carries us out again, after a lot of too-ing and fro-ing, we finally make it and crawl through the shallow rocks and surf and sit on the beach to catch our breath.

Now to work. A year ago, the New Zealand Government in collaboration with PIPA, Conservation International and the New England Aquarium funded a rat eradication program here. In 2005, before PIPA was created by Kiribati, a Korean fishing vessel shipwrecked on McKean's shore (Sitting on the beach with my wet cloths pasted to my body, I can see the wreckage now on the far side of the island: rusted mast and stern section awash in the surf). Story has it the crew was drunk and drove right into the island.


Asian rat Rattus tanezumi (Photo: siamensis.org)

Most ships have Asian rats as permanent residents, especially the old commercial fishing vessels. The rats jumped this ship on McKean as it crashed and came apart in the surf, the rats had their own swim ashore after which they established prosperous rat lives on the island eating the birds and eggs for the first time in history. The rats preyed on the defenseless birds that had evolved as ground nesting behavior--eggs just laid on the bare ground, everywhere.


(Photo: Greg Stone)

Under the overall PIPA management plan, the New Zealand Government paid to have the rats eradicated by a team that came here and laid rat poison stations to kill them. A poison system that would kill nothing but the rats. Our job was to check the bait stations and look for evidence of rats to see if it had been successful. Good news! I found many bait stations with fresh bait, meaning that the rats were probably gone, and no eggs with rat chew marks on them. The amazing bird life on McKean was once again safe from rats.


A rat trap (Photo: Greg Stone)

The swim out was easier, as the same surf that pushes us away form the island now carried us out to the waiting skiff. Back to NAI'A, back to the buzz of the ship and back to SCUBA diving surveys.

Read more about the McKean Island landing from Kate Madin on the WHOI Expedition Blog.

-Greg Stone, PIPA Expedition Leader

[Learn how continued McKean eradication efforts are going in this post from 2012, an interview with the person in charge of restoring ecosystems on these tropical atolls.]