Well, that's rather different to "fighting chicken", don't you think?
Now that you've given us the correct information, I can confirm that yes, Lowan is the word for mallee fowl in the Wemba-Wemba language, spoken in the north of
Victoria, Australia. Note that it's a
word, and was not used as a name in Wemba-Wemba. If Lowan as a first name has been used in Australia it'll have been used by non-Aboriginal Australians who have borrowed the word from Wemba-Wemba.
However, I have never personally heard it used in Australia, and I still think it's far more likely that the use of Lowan as a first name has come from the Irish surname, not the Wemba-Wemba word.