It may be worthwhile to see a photo of some of the Cache River habitat. In "The Grail Bird", there's a picture taken of the spot where Gallagher and Harrison saw their "Ivory-bill" in February 2004. This picture was taken just 30 minutes after the sighting.
I don't have a direct link to the picture, but you may be able to use Amazon's "Search Inside the Book" feature to see it online. Here's a link to the book. If you move your cursor over the picture of the book cover on the left, a search box should come up. If you type in "gene sparling paddles his kayak" in that box, you should be able to click on the resulting link to see the picture.
Note that the habitat doesn't seem to be a good match for the ancient, mature habitat that the Ivory-bill was said to prefer.
Please also note the lack of cover in the bare, leafless trees. During a massive search effort, I think it would be virtually impossible for a large, conspicuous, noisy Ivory-bill to be seen 8-18 times in this area without anyone getting good looks and good pictures.