Pacific Bird watching in Kiribati
Despite recent declines, Christmas Island, (or Kiritimati), still has the highest species diversity and largest bird population of any oceanic island in the world.
Up to 6 million birds can be on Kiritimati during the peak of the breeding season — including several million pairs of Sooty Terns (Sterna fuscata).
Kiritimati or Christmas Island is part of Kiribati, an island nation located in the central tropical Pacific that comprises 33 atolls dispersed over 3,500,000 square kilometres straddling the equator and close to the International Date Line.
Kiritimati’s birds includes 18 breeding species of seabirds and the largest global population of two endangered species – Phoenix Petrel and Polynesian Storm-petrels. The main threats to these birds are from rats and illegal poaching of eggs and birds for food.
Raining seabirds on Motu Tabu
From a distance it looks like it’s raining seabirds on Motu Tabu island - a small island in the main lagoon at Christmas Island (Kiritimati).
As you get closer, you can pick out the different species in flight over the atoll – hundreds of shearwaters, petrels, terns, noddies, frigatebirds and boobies. These are just some of the seabirds you can see by day on this tiny 3.5 hectare atoll.
White Terns and Black Noddies are the most numerous birds, but you also have to watch carefully to avoid stepping on the thousands of ground-nesting seabirds in the peak season.
The birds are monitored by local rangers of Kiribati’s Wildlife Conservation Unit and in recent years they have noticed a steady decline in several species, including Phoenix Petrels that have declined from a population of about 20-25,000 in the 1980s. Less is known about the populations of the Polynesian Storm-petrel, but it is believed they will be facing a similar drop in numbers.
Rats predate nests
Polynesian rats (kimoa) have inhabited Christmas Island for about 100 years and more recently spread to some of the smaller lagoon islets. These rats are mainly a threat to smaller seabirds, but the arrival of the larger Black rats are a newer and potentially more devastating threat.
Recent monitoring has shown that there are no rats on either Motu Tabu or the other main seabird islet, called Cook Island. Plans are now underway to protect the seabird populations further by removing these invasive pests from other islets within the Kiritimati atoll.
Motu Tabu is a low coral atoll of white sand and shell with varied vegetation that includes portulaca, scaevola, sesuvium, lepturus grass and salt bush.
This island is one of the largest breeding refuges of Phoenix petrels (Pterodroma alba), a medium sized dark-brown petrel with a distinctive white throat, white underparts, and fast, swooping flight.
The tiny White-throated or Polynesian Storm Petrel (Nesofregretta fuliginosa) is also found on Motu Tabu, and nests in burrows of lepturus grass or sesuvium. This species is classified as Vulnerable on the ICUN Red List of endangered birds with some of its largest colonies found on Kiritimati.
Like many storm petrels it forages off-shore by surface feeding, flying just above the surface of the water and feeding on squid, crustaceans and small fish.
Last stronghold for species
Rats and cats have reduced many of its breeding colonies in other areas of Polynesia, and Kiritimati is one of the last strongholds for this species.
Competing for breeding space with these and other seabirds, is the Christmas Shearwater or Te Tinebu (Puffinus nativitatis). This medium sized dark brown shearwater with a distinctive rounded tail, also breeds in burrows or under vegetation. They are common around Kiritimati and found only in the central Pacific, where they are usually seen foraging offshore in flocks for fish and squid. Like many of the birds on Kiritimati, the biggest threats to their survival are kimoa, cats, pigs, poaching and crushing of nests.
Sooty Terns are abundant on Motu Tabu and other areas of Kiritimati such as Cook Island where thousands nest on the ground in dense colonies during the breeding season. The numbers breeding at Kiritimati has declined from about 25 million in the 1960s to 2-3 million now with predation by rats and cats and poaching of eggs the main problem.
Tropicbirds and Boobies
Red-tailed Tropicbirds are common breeders in Kiritimati and many nest under vegetation on Motu Tabu. Red-tailed Tropicbirds (Phaethon rubricauda) occur in good numbers in Kiritimati and are widespread throughout the Pacific, despite the threat of predation from rats, cats and pigs, and poaching by humans.
These birds also forage off-shore, plunge diving on fish, squid and flying fish.
A few White-tailed Tropicbirds were also seen on Motu Tabu. Unlike the Red-tailed tropicbirds, these always nest off the ground, usually in a tree or cliff-site.
Three booby species are found on Motu Tabu, including the Masked Booby, the Brown Booby and a light-phase Red-footed Booby. The Red-footed Booby is the only one that nests off the ground, usually in a rough nest of sticks in low saltbush.
Frigatebird species seen on Motu Tabu include the Greater and Lesser Frigatebird, both of which nest in low bushes on a large nest of sticks. Male Greater Frigatebirds construct a nest and attempt to attract passing in-flight females by sitting in the nest and inflating their large red throat sac in a courtship display.
Protection from poaching threat
Poaching by local inhabitants is a significant threat to seabirds on Kiritimati as the population increases with people relocated from other areas of Kiribati such as Tarawa. There are now about 5000 people on Kiritimati and poaching of eggs, chicks and adult seabirds has increased as people look for other natural food sources besides fishing. The Wildlife Conservation Unit rangers are involved in protecting many of the islets from poachers.
For those interested in visiting Kiritimati, there is a bird field guide in development by the Kiribati Wildlife Conservation Unit that is based in Kiritimati. Kiritimati is reached via airline flights between Fiji and Hawaii.