On one of our last days of research on the motus of Aitutaki, the sandy beach crew sampled the motu of Maina. To our surprise, this motu turned out to be a nesting site for red-tailed tropic birds (Phaethon rubricauda) and we were sampling during breeding season. Like other seabird species, tropic birds make very simple nests called scrapes. These scrapes are just small depressions on the back beach made by parents scraping the sand away. I was able to get close to a few nests without disturbing the birds and took some great pictures. It was nice to see the beginning of life take place for these beautiful birds in such a wonderful place. This seemed a nice symbol for our overall trip; this research trip could be the beginning of our lives as naturalists helping out different parts of the world.
The sandy beach crew sampled beaches at two different motus yesterday and found some interesting results. Because sandy beaches tend to be low in diversity on their beach face, we changed our protocol for the Cooks to take more cores in the sand submerged in water than is our norm. As a consequence, we found multiple species of tube worms, horn snails and crabs. One of the larger motus, Motukititu, was naturally built on uplifted coral and had the highest biodiversity of the motus we have sampled. Honeymoon Island (also a motu) had the lowest diversity, although more studies need be conducted to make a clear connection between the structure/geomorphology of an island or given beach and its associated biodiversity.
Another interesting observation we have made about these moths revolves around the imprints in the sand. In California, we are so used to seeing every beach filled with divots made with footsteps, we have assumed this look to be normal. On the nearly untouched motus of Aitutaki, the beaches lack such ubiquitous divots, but do have hundreds of hermit crab tracks, shells, and pristine, smooth sand.
The group visited a marine lab on Aitutaki today and met with Charlie Waters. Charlie recently finished a PhD focused on the giant clams of the Cook Islands. These clams were heavily overfished until they became functionally extinct (could not reproduce in the wild). Clams are important filter feeders in the reef ecosystem and are an important food source for octopus, porcupine fish, parasitoid snails, humans and multiple other animals.
The clams engage in a symbiotic relationship with phytoplankton (photosynthesizing plankton). The clams rely on the plankton for energy and have trouble surviving without the phytoplankton.
The lab has tried to implement reintroduction of multiple species of clams but poaching continues to ruin the efforts. In an attempt to come up with a solution, Charlie believes the best method is to educate youth and tourists on respecting the reef system. Hopefully these educational programs will eventually allow a successful reintroduction of these beautiful animals to their natural habitat.
We went snorkeling in the lagoon of Aitutaki Island and explored some of the smaller Islands in the lagoon called “motus”. The first was named Motu Ketiu and had multiple species of birds nesting on the Motu. I was able to identify red footed boobies, brown boobies, red tailed tropic birds, white tailed tropic birds, common terns, and I was excited to see my first frigate birds.
The next Motu was a newly formed sand bar that had a few coconut saplings (locally called “huto”). We had lunch and made our first UAV launch from this particular Motu.
We then ventured to a large Motu where the Tasmanian Empire Airways Limited had set up a stopping point in the early 1950s. Here we tested our sandy beach protocol and found that the beaches on these motus are low in diversity unless coring is done in knee deep water, where multiple species of tube worms and crustaceans were found.
Overall, quite a few discoveries were made today that filled the group with anticipation for the future research yet to be done.
I had the joy of observing one of my personal favorite invertebrate species today. The fiddler crab is an interesting crab species that is known for it’s oversized claw. Only the males have the large claw and use it to impress female crabs by waving. In order to avoid scaring the crabs, I sat and stayed still to watch them eat and continue building their burrows. When they were assured that I was no threat, some males began waving to impress some of the females in the group but many focused on eating and wouldn’t have
any mating shenanigans.
This is a female:
Our days spent on Rarotonga proved to be full of excitement and a great introduction to the Cook Islands’ culture. We were able to experience the 50th anniversary performances at the island’s auditorium. I have learned that the Cook Islanders have 3 names for coconuts and relied on the coconut tree for food, drink, baskets, and clothing throughout their history.
The reef biodiversity is immense and full of clams that can live longer than humans and weigh over 50 pounds. I have had the privilege of seeing more species of fish in one trip than my entire life.
Now that we are in Aitutaki, every look out of a window fills us with anticipation for the work to come.
When I first found out I was selected for this trip I immediately started looking up the Cook Islands’ biodiversity. I found bird checklists and I found that my favorite species of crab, the fiddler crab, could be found in the Cooks. I also found that two species of albatross frequent the islands. I cannot wait to find bird and invertebrate species I have never seen before on those islands. I am looking forward to running CI’s sandy beach protocol on the beaches of Aitutaki and finding what kind of diversity lies on the coast. I look forward to learning about the country’s agricultural methods and land management, especially in relation to the conservation and maintenance of the islands’ ecological health.
I am also fond of experiencing new cultures and I love listening to world music when performed by natives of that culture. I am therefore eager to experience the celebrations of the Cook Islands’ independence.
This species of Kingfisher is endemic to Mangaia Island, the southern most Cook Island. Despite it’s relations, this species does not usually eat fish. Most of its diet consists of lizards and skinks. This species’ mating habits are also different than most, they often breed in pairs or trios and switch between polygyny, polyandry, and monogamy. Because the Mangaia Kingfisher is endemic, it is vulnerable to introduced species and habitat fragmentation. More than half of the Cook Islands’ endemic land birds are extinct and better management of land resources can reduce the threat of extinction for birds like the Kingfisher.
Can’t wait for this trip!