Cook Islands Arāpō -a comparison

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Gerald McCormack, CINHT.

Lunar calendars are popular in Polynesia as guides for fishing and planting. In most cases they consist of a series of 30 nights with names (named-nights) that are applied without deviation, except for the 30th night, which can be dropped to ensure the next cycle starts on New Moon. The local calendars are known as the arāpō, literally the “path of the nights”.

In a previous article (30 April), we looked at the astronomical reason why Full Moon varies –more– between the 15th, 16th and 17th night, namely ‘Otu, Mārangi or Turu of the Ministry of Agriculture arāpō. The First Quarter and Last Quarter also vary over three nights: 7th, 8th and 9th for the First Quarter, and 22nd, 23rd and 24th for the Last Quarter. In the table I have shown this 3-night variation in the left column and removed all references to actual astronomical events from the calendars of named-nights.

In this article we compare some commonly accepted lunar calendars to see how they might have evolved since ancient times.


Settlement of Eastern Polynesia

The evidence from archaeology, linguistics, and DNA shows that a voyaging people, the Lapita people, were the first settlers in the islands of Fiji, Tonga and Samoa, about 3000 years ago (1000 BC).  During the next 2000 years they were a settled people and during that time they developed the first Polynesian language and culture.

Around 1000 AD they set forth to discover and colonise the Society Islands and Tuamotu Archipelago, where they remained settled for about 200 years and during that time they developed the first Eastern Polynesian language and culture.

From about 1200 to 1400 AD they discovered and settled all the remote islands of Eastern Polynesia from Hawai‘i in the north, to Rapanui in the southeast and New Zealand in the southwest.

Samoa and the Society Islands

We cannot travel back in time a 1000 years to look at the lunar calendar brought by the first settlers to the Societies. In the table we show modern calendars from Samoa and Tahiti, and what is immediately obvious is that they have nothing in common.

Although this modern Samoan calendar will have changed, it is unlikely to be radically different from that of the ‘Samoan’ community of 1000 years ago, which means that the Tahitian calendar shows radical innovation. It is as though a founding ‘Samoan’ chief said “forget Savai‘i, let’s develop a new language and culture, and a revolutionary lunar calendar” – and so it was.


Which Tahitian calendar is the most ancient? The scholar Rev John Davies recorded the Pomare calendar in 1819, and the linguist Frank Stimson analysed three Society Islands’ calendars in 1928. The Davies/Pomare and Stimson #1 and #3 have the same named-nights and sequence, except that the 11th can be Rapu or ‘Ari, and the system of counting repetitive nights can be mua, roto and muri or tahi, roto and fa‘aoti – a trivial difference of “first, within and behind” versus “first, within and end”.

Stimson #2 is like the others, except that after New Moon, when the moon is waxing, the repetitive nights have three Tamatea nights instead of two ‘Ore‘ore and one Tamatea. Overall, the remarkable similarity in the Tahitian calendars supports the idea that they have changed little over several hundred years.

Here we show Stimson’s #3 because its counting system (tahi, roto, fa‘aoti) is the same as those of the Cook Islands.

Societies to the Cook Islands

Oral traditions, linguistics and archaeology show that the Southern Group islands were mainly settled from about 1200 to 1400AD with settlers from the Society Islands. These settlers would have brought their arāpō and we would expect Cook Islands arāpō to reflect a common ancestry.


There are a few Rarotonga arāpō and we are using the Ministry of Agriculture’s, which has been widely used since the 1990s. This calendar is the same as that recorded by Taira Rere in 1960, except it replaces Rapu with Vari, and Mai with ‘Otu, and it swaps around a couple of adjacent nights – trivial differences.

In comparing the Rarotonga calendar with the Tahitian we see they are the same, except for a reversal of named-nights 10 and 11, and the use of Vari instead of Rapu (while noting that Rere 1960 used Rapu).

The Outer Islands

Reverend William Wyatt Gill spent 25 years on Mangaia from 1852 and he was a prolific recorder of Mangaia culture. We use the Mangaia calendar he published in 1876, which is the same as those used today.

I have recorded various calendars from Ngāpūtoru since the 1990s and the one shown here for Ātiu is the same as one recorded on Ma‘uke, while the only one I recorded on Miti‘āro (not shown) was similar to Rarotonga. The one shown for Aitutaki was recorded at the NBSAP meeting of 2000, and is essentially the same as the one used in the schools today.

Compared to the Tahitian calendar, the Mangaia, Ātiu and Ma‘uke calendars have only one significant difference: during the waxing moon repetitive nights the lone Tamatea has increased to two nights and moved ahead of the maintained two ‘Ore‘ore nights, and Hamiama has been reduced from three to two. Although the Aitutaki calendar might at first look quite different it is the same as the other Outer Islands, except they have removed ‘Akaoti Korekore from each sequence to make a calendar of 28 nights instead of 30.

Mystery remains

The Mangaia, Ngāpūtoru and Aitutaki have essentially the same arāpō despite being settled by different groups from the Societies, and having had little cultural interaction after about 1500AD. This indicates they inherited it from a widespread ancient calendar of the Society Islands. Therefore, it might be that the present Tahitian and Rarotonga calendars have undergone a more recent alteration of the repetitive nights of the waxing moon.

This idea is supported by William Wyatt Gill (1876) who wrote “At Rarotonga the 13th is Maitu instead of Atua; otherwise this account of the changes of the moon [for Mangaia] is equally good for Rarotonga.” Anthropologist Percy Smith, who did extensive interviewing on Rarotonga in 1897, recorded an arāpō which also has the Outer Islands’ system of repetitive nights during the waxing moon.

It is not clear if the present Tahitian calendar is ancient or a more recent innovation, and it is not clear when that calendar arrived on Rarotonga. An analysis of lunar calendars from other islands in Eastern Polynesia could shed light on this mystery.


McCormack, Gerald (2024) Cook Islands Arāpō – a Comparison.

Author’s notes
First published CI News 22 Sep. 2011.



Gerald McCormack

Posted by Gerald

Gerald has worked on Cook Islands marine and terrestrial biodiversity since 1980. He was the foundation Director of the Natural Heritage Trust from 1990 to 2020.

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