I had to search for the meaning of 'potlatch'.... seems that it is a tradition, right? Anyway, in simpler english, the sentence says 'the chief escaped his home and he took the bird as a special thing, where he declared this right at a potlach.' i think your main problem is that 'proclaiming this right' is different from 'proclaiming this, right at' 'proclaiming this right' sounds like a politic speech, where someone is declaring some law or rights. 'proclaiming this, right at...' means the chef proclaimed that object (the bird), right at [somewhere] still... the phrase is kinda weird, because he seems to be 'proclaiming a bird'. it doesn't make much sense to me!

I can't understand the sentence. Check the difference between "rite" and "right." That my solve the problem.