I’ve discussed this issue in depth with someone who’s very familiar with Tanner’s notes, the Allen and Kellogg paper, etc., although not with the LSU map. I am now persuaded Tanner concluded that nests III and IV from 1935 were not nests after all and that he assigned the birds involved to Titepaper (Nest III) and Bayou Despair (Nest IV). Nest IV is apparently one that Kuhn found but was unable to re-locate. It’s still unclear why there’s no mention the ’34 nest.
It’s very difficult to piece together this fragmentary information, and the monograph muddies the waters a bit by presenting the home ranges of the birds as being quite discreet, perhaps a good deal more than they were in fact. I’m also left to wonder whether the “nests” that Tanner excluded were actually roosts, which seems the likeliest explanation. If this is so, the roosts would have been well outside the home ranges Tanner identified and closer to the core of the John’s Bayou range than to the core of Titepaper or Bayou Despair.
On further edit: I have now re-read the Allen and Kellogg paper and am convinced that the nest numbered 3 in the Brand photograph is actually from Mack’s Bayou, which Allen and Kellogg described as being in a Pin Oak snag that was found in a natural clearing.