The word Yugarabul is composed of the language name Yagara E23 + a suffix -bul with uncertain function. Harper's letter to the editor in 1894 describes the dialectal relationships and group identity between: 'Yagara- speakers, whatever their dialect, were well aware of the fact that all spoke the same language, indicating that ... [all of the people] ... along the south side of Moreton Bay and all along its shores to Amity Point use the word Yug-ger-a-bool to signify their respective dialects.'
Watson (PMS 5355) treats Turubul E86 as a sub-group of Yugarabul (E66). There is a word list by Hardcastle (1963) and also by Watson (1943 and PMS 5355).
There seems little likelihood that Yagara E23 and Yagarabul refer to different varieties; Hardcastle, referred to the Lockyer Valley people as speakers of Yaggarabal (E66) as did Harper about the people of Moreton Bay. There are word lists by Hardcastle and Watson.
See and use Yuggera language E23.
Harper, E. 1894 [letter to editor] The Queenslander 01-09-1894
Watson, F. J. 1943. Vocabularies of four representative tribes of south eastern Queensland, with grammatical notes thereof and some notes on manners and customs; also a list of Aboriginal place names and their derivations. Brisbane: Royal Geographical Society of Australasia.
Watson, F. J. 1940. A vocabulary of the language of the Yugarabul lingual division of Australian Aborigines and incidentally of the Turrbul sub tribe at Brisbane, typescript. (PMS 5355).
The territory of the Yugarabul lingual division practically coincides with the basins of the Brisbane and Calloture Rivers extending nearly to the Glasshouse Mountain Group in the north to a little south of the Brisbane River near the coast; from the Pacific Ocean to the Dividing Range, extending north west to or beyond Esk and south from there to the Peaked Mountains and the Teviot Range (Watson PMS 5355). Boonah district and Teviot Valley (Hardcastle 1963). (Note that these two locations are discontinuous. Caboolture is north of Brisbane and Boonah district is south of Ipswich. Between Brisbane and Ipswich is Yakara.)
Speaker numbers were measured differently across the censuses and various other sources listed in AUSTLANG. You are encouraged to refer to the sources.
Speaker numbers for ‘NILS 2004’ and ‘2005 estimate’ come from 'Table F.3: Numbers of speakers of Australian Indigenous languages (various surveys)' in 'Appendix F NILS endangerment and absolute number results' in McConvell, Marmion and McNicol 2005, pages 198-230 (PDF, 2.5MB).