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IVORY-BILLS  LiVE???!  ...

=> THE blog devoted to news and commentary on the most iconic bird in American ornithology, the Ivory-billed Woodpecker (IBWO)... and... sometimes other schtuff.
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Thursday, December 16, 2010

 

-- Auburn Back Up --

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The Auburn Choctawhatchee search pages are back up now here:

http://www.auburn.edu/academic/science_math/cosam/departments/biology/faculty/webpages/hill/ivorybill/

[...someone a few posts back was asking where details of Tyler Hicks' sightings could be found; they are included here:
http://www.auburn.edu/academic/science_math/cosam/departments/biology/faculty/webpages/hill/ivorybill/FieldNotes2006.pdf ]

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Comments:
Just a note of correction to something I related in my interview below. I expressed my opinion that the most impressive recent ivory-bill sighting was one reported by Tyler Hicks in Dec 2005. I was confusing this sighting with another he reported in Dec 2006. In this later sighting the bird was perched (briefly). This sighting is not described in the pdf but is related on Geoff's updates page.
 
Thanks for that clarification. I found the 12/06 encounter description in the updates as you indicated. It is indeed impressive.

I have retrospectively studied the Auburn U search as I did the Cornell/Big Woods search. Having read about other hot spots of sightings in the past few decades there is a pattern emerging. The birds are present for two or three years...and then they are gone.

Could this movement be due to pressure from the searchers? Just a natural following of food supplies? Putting aside questions about the validity of any of these clusters of sightings...it would be extremely interesting to figure out this part of the puzzle. Where do these birds migrate when they leave an area...any why?

Dan
 
There are those who would argue that the search efforts themselves were a major factor. But I think it's important to keep in mind that this woodpecker is highly unusual in its morphology. It is built for distance. Why? I think this is a good example of the importance of looking past Tanner’s illustrations and his loose utilization of the word territory to what he and Kuhn actually observed. Only one pair of ivory-bills was ever documented as nesting within a 1 square-mile area for more than a few years. Tanner saw NO indications that ivory-bill pairs were intolerant of other pairs within their home ranges. Here we have a bird which, because of its ability to strip bark and excavate quickly, is able to take advantage of forage blooms like no other. I submit that unless forest conditions are ideal, the birds will not linger in a given area for long. Why should they? The only reason most woodpeckers do this is that they are highly territorial. Abandoning an established territory is very risky. If there is another of better quality around, chances are it will be occupied and vigorously defended. But if you are not territorial, and can take advantage of local forage blooms, the best strategy is to move often. Some historical accounts have as many as 11 ivory-bills foraging within a small area.

It is worth noting that forestry has, for 100 years or so, done its best to keep forests “healthy.” Unfortunately, healthy trees are not what ivory-bills and many other species need. Thinning may help small gap-loving birds and other animals, but it does little for large woodpeckers. Only time is going to solve some of these problems. Cypress can live 500-2000 years. I see areas that were cut 100 years ago. They have some pretty large cypresses. But the cypress mortality is negligible. These places will need centuries to produce good densities of large snags. And then there is disturbance. A fire occurred in the Singer Tract in the 1920’s, and of course there was the great flood of 1927. Both of these are far more controlled in today’s landscape. Is morticulture the answer? I think it’s worth some experimentation, but my suspicion is that in today’s forests, the limitation is often more a matter of optimal nesting sites than forage.
 
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