Let's put this to rest, and I'll go off the woodpecker theme here for a while. An Ivory-billed woodpecker need not be especially wary, nor in an extremely remote habitat, to avoid detection for many years. It just has to be RARE.
The density of Pileated Woodpeckers in the area where the Ivorybills were sighted in Arkansas has been reported as 40/mi2. And the total area of the Big Woods is called 250 mi2 in a frequently bandied number. So lets be generous and give the Big Woods 5 Ivorybills, or one per 50mi2. And let's assume that is it as conspicuous as the Pileated. Given this, you would expect to detect one Ivorybill for every 2000 Pileateds.
But wait, that is just a detection. As we all know, we do "80% of our birding by ear." And is a heard-only Ivorybill good enough? Of course not. Is a quick glimpse of a big woodpecker with a general impression of how much white it has enough? It's enough to count a Pileated, but not for an Ivorybill. No, we need a good look. So again being a bit generous let's say 10% of these "detections" would be good enough for you to even consider making a public announcement that "Oh my god I am pretty sure I just saw an Ivorybill!" Now we are at one Ivorybill per 20,000 Pileateds.
To put this in context: that is a Pileated a day for over 50 years. It is nearly 40 times the number of Pileateds EVER recorded on the White River NWR Christmas Bird Count in the 35 years it has been conducted. In the Big Woods, I detected about 2 pileateds per hour (mostly by voice). Laura Erickson has been reporting about 1-2 per hour on her trip too it seems. So that is one glimpse of an Ivorybill per 10,000-20,000 observer hours. 10,000 observer hours is 10 hours a day, every day, for three years. Even someone who lives and works at the refuge, with all his or her other duties, would probably not chalk up 20,000 Pileateds in a decade even if they were a birder and trying to pay attention. I know here at home I detect about one pileated per 1-2 hours when I am birding, only about one a day (or less) when I am going about my regular farm chores.
But even after all that, all we have is a sight record. Quite probably a brief one that would still leave much detail to be desired. Events of the last year prove you need a photo or video, and indeed a good photo or video. Laura hasn't gotten even one decent Pileated photo per day on her trip. So, realistically, we might need to add another order of magnitude here and say one acceptably photographed and unequivocally documented Ivorybill per 200,000 Pileateds, or 100,000 observer hours, and only if that observer is carrying a camera
A hundred thousand observer hours. Ten hours a day, every day, for 30 years. Ten hours a weekend for 200 years. About a full years' worth of christmas counts.. and I mean all the christmas counts, every single party hour on every christmas count conducted anywhere in the continent, all transplanted to the Big Woods. And everyone carrying a camera. Or more realistically, 10 camera-equipped parties spending 10 hours a day in the field every day... for three years.
So the "skeptics" can already start rejoicing. Odds are, even if there are five Ivorybills in the Big Woods, and even if they are no more wary than Pileateds, there will not be an unequivocal photograph taken this year. Or next. There will be some sightings, a few of them probably even pretty good ones. There will likely be a fair number of maybe's, might-have-been's, and sure-sounded-like-one's -- all of which would be enough to count a common bird on a CBC but not enough to document an Ivorybill.
The bird does not have to be extinct, or especially wary, or living only at the ends of the earth, to have avoided having its portrait snapped for all these years. It just has to have had a very low population density.