Taiwan is not only home to Chinese language such as Taiwanese, Mandarin, and Hakka but it is also home to Austronesian languages such as Atayal, Paiwan, Tsou, Rukai, Ami, and others. Yami is the only Austronesian language spoken in Taiwan that is considered part of the vast Malayo-Polynesian subfamily that includes languages as far west as Malagasy and as far east as Hawaiian and Rapa Nui.
Yami, Ivatan, and Itbayat belong to the Bashiic-Central Luzon-Northern Mindoro (henceforth, BCN) subfamily of the Northern Philippine branch. The most famous BCN language is one of the 12 most spoken languages in the Philippines, Kapampangan. The position of Kapampangan in this category is still pretty much shaky, but that's a whole other blog entry.
In any case, I have encountered a very interesting website dedicated to the Yami language. The URL is: http://www.uga.edu/~asian-lp/jpn_html/yami/content.html
Knowing that Yami is related to the languages of the Batanes Islands, I wondered if it was mutually intelligible with them. The third chapter, The Common Origin of Bashiic cultures answered that for me. Apparently if the speakers try speaking their respective languages without foreign borrowings then their mutual intelligiblity is highly increased. For an Ivatan, this meant avoiding Spanish, English, & Tagalog words and a Yami had to avoid using Chinese & Japanese words.
I found the following passage, under "intercomprehension", particularly fascinating:
... In 1986 I succeeded in taking along a Yami friend named Si-Mogaz (male, 39), when I traveled from Irala to Ivatan and to Itbayat. My main curiosity was to see how well, after several hundreds of years of isolation, they could communicate with each other. Now we had living people at hand with a strong desire to communicate, which made the testing of mutual comprehension very different from the previous attempts with the recordings. The results showed themselves within the first hours of conversation. Si-Mogaz felt uncomfortable with the negative form of the Ivatan verb and was somewhat discouraged by the Spanish and English loanwords. As the hours passed, however, his conversation became more self-confident and a few very clear communication behavior patterns started surfacing. Both sides had realized by then that Spanish, English, and Tagalog loanwords on the one side, or Chinese and Japanese loanwords on the other, did not work, so they started eliminating them by looking for synonyms in their own languages. This spontaneous, instinctive response caused an unusual feeling of excitement for the conversants, as if they had understood subconsciously that they were making efforts to reconstruct the language of their common ancestors. Almost every time they succeeded in finding a proper synonym for a native word or bypassed an acculturated element of their contemporary vocabulary by finding a commonly understood synonym, they had to pause to express their excitement by saying: "we are relatives indeed," or "we surely have common origin." In the case of those Spanish words for which there were no Ivatan synonyms, or which were so strongly embedded in usage that the Ivatans could not work their way around them, to my greatest amazement Si-Mogaz started picking them up. At the end of the day he was using correctly the word siguro, which comes from the Spanish "sure." In Ivatanen it is used for "perhaps" and there is no exact Yami equivalent for it. ...Very cool. Please be sure to read the transcriptions of two stories in Yami to get a feel for the language and to see similarities with other Philippine languages; Nikapowan no tawo do yayo (The creation myth of Yayo) and Nikapowan no tawo do tawo d'Iranmilek (The Creation Myth of Iranmilek). The list of Yami vocabulary is worth visiting as well.
The site also includes an extremely brief grammar & phonology. There are phonemes that are not prevalent in other Philippine languages such as a uvular stop found in Arabic and retroflex stops. On Dr. Rubino's page, you can read a brief description of Ivatan grammar.
And below is a map of the Bashiic area. Click it to enlarge. Enjoy!