SUMMARY
Paku language gets shifted in connection to fading its language vitality away. The decreasing number of native speakers of Paku language has probably resulted from language contact with other surrounding languages. As a consequence, the natives gradually become bilingual, even multilingual. Some dominant languages around the speech area of Paku language include Dayak Maanyan, Banjar, and Indonesian languages. Regarding economic factors, the natives interact with others who use other languages. Hence, the Paku tribe shifts to use Dayak Maanyan language for daily interaction since Dayak Maanyan language is categorized as the lingua franca along the Barito River. Both Paku and Dayak Manyaan languages are lexically similar. Besides, Dayak Maanyan and Paku languages are included as a language family. As a result, the natives of Paku language have no difficulties to become bilinguals by speaking both Paku and Dayak Maanyan languages. Unfortunately, this tends to make the natives uninterested in using the Paku language. These are also considered as an initial step of the current loss of Paku language vitality in East Barito regency. This study focuses on language shift in terms of its usage and language vitality level of Paku language. It deployed a descriptive method. The data were obtained from informants in the speech event happening in some domains of language use in Bantai Napu subdistrict. The data were then analyzed by some steps, that are (1) classifying Paku language used concerning its domain, (2) identifying language shifts on Paku language usage, (3) measuring Paku language vitality level with using UNESCO and EGIDS scales, and (4) concluding.