20.03.2021 - The birds of Kouaku, Gambiers Islands

Kouaku is the southernmost little sandy island - Motu - in the Gambiers. The vegetation consists mainly of native shrubs and trees with only a few coconut trees. If you go ashore you are welcomed by lots of noddies and terns, which circle above you. This is because if you wander closer the birds get agitated and circle above after giving a warning signal to the other birds. Especially if it is a nesting area. Normally only a few birds fly around the motu or sit in groups on the sandy beach. We always love to find islands where there are still a lot of birds.

There are mainly two different bird species on Kouaku, which also use the island as nesting area. The wonderful, brilliant white White Terns (Gygis alba) as well as the Black Noddies (Anous minutus). We also saw some Brown Noddies (Anous stolidus) and Red-footed Boobies (Sula sula). Most seabirds simply nest on the ground, some building nests, others just laying there eggs in a sandy hollow. This was not a problem before people together with their animals arrived on those oceanic islands. Cats, dogs, pigs, goats and rats pose a severe threat to seabird populations. The arrival of humans and their intentional and unintentional introduction of animals now prevent the successful nesting of seabirds in a lot of places, since the eggs and chicks are easy prey for both, humans and animals.

White terns and noddies do not nest on the ground but use shrubs and trees. The black noddies look similar to the brown noddies but are a little smaller and have a longer and straighter beak. The name noddy comes from their mating behavior, because they always nod with their heads during courtship. They feed on small fish and squid and usually hunt in bigger groups. If big fish drive a school of small fish towards the surface, noddies will see this and start catching fish from above. As soon as we see a big group of noddies above the water we know there must be a lot of fish around.

Noddies build small nests on branches of shrubs and trees, which consist of twigs, leaves and bird excrements. They use the same nest more than once and always lay only one egg. The chicks look similar to the adults, dark brown with a white cap on their head. Once in a while a chick might fall out of the nest or tree and hide on the ground. Luckily we observed that those chicks are still fed by the parents.

In contrast, the white terns also nest on trees but do not build a nest. They lay their single egg simply on a branch. The advantage is that the eggs can not be attacked by nest parasites, but the disadvantage obviously is that the eggs and later chicks can easily fall down in stronger winds. Luckily they can lay another egg pretty quickly if this happens. Therefore the chicks already have highly developed feet to hold on to branches. On Kouaku we can observe everything from eggs to freshly hatched chicks up to almost grown ones. If you get closer to a chick they tend to remain completely still and try to melt into their surroundings. Some look like small owls sitting in the tree. Once in a while you can watch how they are fed with small fish by their parents. If they are freshly hatched they have the same grayish color as the bark of the trees. When they grow, the feathers become more and more white until they are brilliant white when they are grown and often reflect the blue of the ocean surface when they fly. White terns tend to live very long. One individual is known to be be at least 42 years old, which is remarkable for a small sea bird.

In the evenings we usually also see red-footed bobbies (Sula sula) resting in the trees. But if they nest around Gambier we do not know. At least we have never seen nests anywhere. There are also other bird species in the Gambier islands. On some of the southern islands the rats were eradicated and artificial nesting sites created to attract other sea birds (petrels and shearwaters) and give them a safe place to nest.

We are glad that there are at least a few places where you can find an abundance of birds. Those islands need some prerequisites like no disturbance through humans (collecting eggs, hunting birds), no or only very few coconut trees, because those can not be used for nesting or as shelter, as well as the absence of rats and other predators of their eggs and chicks. Also, humans are a threat since many still collect eggs. Lately studies have found that bird islands are very important for the health of coral reefs since the birds bring nutrients - in form of fish and squid - from big ocean areas to the islands and improve the growth of plankton through their excrements, which enhances the food supply for fish and other marine organisms close to the island. Bird islands are important for the ecosystem ocean and so we are always happy to find special places like this.