Hirawanu Tapu (known also as Maitarawai and Taputehara Maitara) was born about 1824 at Te Awapātiki on the east coast of Chatham Island. He was a member of the Ōwenga Moriori tribe. His mother's name was either Rūnanga or Hirimaru. His father has not been identified. Tapu had one acknowledged half-brother, Wī Tīpene Matahuri.
Little is known about Hirawanu's early life. He was still living at Te Awapātiki when Te Āti Awa invaded the Chathams in November and December 1835. Thereafter he was enslaved by Ngāti Tama and taken by them in turn to Waitahi, Ngātikitiki, and finally Kaingaroa, where he belonged to the chief Wiremu Kīngi Meremere.
Resident Magistrate Archibald Shand recorded in January 1859 that Hirawanu Tapu had been betrothed to a Moriori woman, Rohana (also known as Tini Waihe), who had been a slave of Ngāti Mutunga on the Auckland Islands from 1842 to 1856. Rohana's owner, Matioro, tried to prevent the union by abducting her and carrying her back to Waitangi, Chatham Island. But Hirawanu and Rohana were living together by 1861.
Hirawanu Tapu obtained his freedom when Meremere died in 1860. He returned to his own people at Ōwenga on the south-east coast of Chatham Island. There he became the protégé of and heir apparent to Tōrea Takerehe, who had been influential in persuading the Moriori not to fight the Māori invaders in 1835 and 1836.
By this time Tapu was fluent in written and spoken Māori, and he understood Moriori and spoke a little English. At Ōwenga his linguistic versatility and his ability to calculate rapidly led to his taking charge of bartering between visiting ships' crews (largely whalers) and local residents. He would make a line of standing baskets of potatoes, and whalers would then have to measure out a roll of cloth to the same length.
When the Moriori held their second great council at Te Awapātiki in 1862, to record their traditions and genealogies, and their objections to the Māori conquest of the Chatham Islands, Tapu was chosen as scribe for that meeting and the series that followed. From this time, although Tapu was neither a hereditary chief nor, as yet, an elder, he was regarded by everybody on Chatham Island as leader or spokesman for the Moriori. Communications to and from successive governors and governments were directed through him. Visitors who wanted to discuss Moriori history and customs, such as Stephenson Percy Smith and Edward Tregear, began their inquiries with Hirawanu Tapu.
Because of his literacy, numeracy and general reliability, Resident Magistrate William Thomas appointed Tapu tidewaiter at Ōwenga in the mid 1860s. This required him to record customs transactions at the port and prevent smuggling. He achieved this position over the claims of European and Māori residents, and over the objections of Ngāti Mutunga chief Apitia Punga.
In 1868, with Tōrea, Rohana and other Ōwenga Moriori, Tapu moved onto land which Apitia Punga had reserved for them at Manukau, two miles south of Ōwenga. The status of this largely bush-covered reserve of 2,000 acres, which bordered the sea, was confirmed by the Native Land Court in 1870.
At those court sittings Tapu was the leading witness for the Moriori claims. He was handicapped, however, by the fact that he had never before participated in judicial proceedings and he was ignorant of both procedure and the need for a planned strategy. He placed all his faith in the concept of British justice, which had been explained to him in glowing terms by a visiting ship's captain. In contrast, many of the Māori who gave evidence at Waitangi in 1870 had already done so previously in Taranaki court hearings. The consequence was that, although Māori and Moriori numbers on the Chathams were roughly equal in 1870 (about 100 of each), the Māori were awarded ownership of 146,289 acres of Chatham Island, or 97.3 per cent; the Moriori 4,100 acres or 2.7 per cent. The Moriori failed to gain any title on Pitt or the outlying islands, which were part of their traditional food sources. The judge had chosen to base his decisions on Māori rather than Moriori customary law, and to recognise Te Āti Awa's right of ownership by conquest.
In 1868 Tapu had begun to help the young licensed native interpreter Alexander Shand (son of the first resident magistrate) to collect Moriori history, traditions, chants and vocabulary. Tapu's part in this collaborative procedure was to interview Moriori authorities such as Tōrea, Minarapa Tamahīwaka, Maikoua Mōhewa, Kirapu Rangikei, Pūmipi Te Rangaranga, Hōri Ngā Māia, Apimereke and Heremaia Tau, recording information in Māori and traditional chants in Moriori. He would then go over this material with Shand, who would raise queries about lacunae or meanings. Where Tapu was unable to answer such questions, he would return to his informants and interview them further. The material gathered was eventually published in the Journal of the Polynesian Society in the 1890s, and in 1911 as a book, The Moriori people of the Chatham Islands: their history and traditions. Tapu was also the sole informant for Resident Magistrate Samuel Deighton's Moriori vocabulary, which Deighton presented to the under secretary of native affairs in 1887. Despite Tapu's inability to speak Moriori fluently and his concentration on some informants to the exclusion of others, more than 90 per cent of the surviving information about Moriori language and culture passed through his hands.
Serious as he was about his work with Shand and Deighton, Tapu was not above teasing some of the would-be scholars who came to his door. In 1892 he solemnly assured Henry Forbes that a giant moa-like bird called the pouwa had once roamed Chatham Island, and that he had seen its bones protruding from Te Whanga Lagoon. And he is reputed to have told Abner Clough that the Moriori were the descendants of Portuguese sealers who had become stranded in the Chathams with their Māori concubines 300 years earlier. There is no evidence in Shand's writings or letters that Tapu believed either story.
Throughout the 1890s Alexander Shand's correspondence records that Tapu became progressively debilitated by tuberculosis and seasonal bouts of influenza. He died at Manukau in May 1900, aged about 76. In spite of arguments over boundaries with his Moriori neighbours in the last years of his life, he remained a leader and a celebrity until his death. The first governor to visit the Chathams, Lord Glasgow, made a special trip to Manukau to meet him in 1895. He continued to appear in the Native Land Court until only weeks before his death, giving evidence on Māori claims in addition to Moriori, because he had outlived and out-remembered Māori witnesses. By that time only 12 'full-blooded' Moriori survived: there was no Moriori of his stature waiting or equipped to assume Tapu's role. Moriori culture died with him in a far more real sense than it did with the death of Tommy Solomon 33 years later.