The Extinct Ivory-billed Woodpecker (Campephilus principalis)

The ivory-billed woodpecker’s extinction (circa 1950) frustrated ornithologists from Cornell University who unsuccessfully tried to save the species in the 1930’s and 1940’s.   In 1942 they knew of only 22 individual birds living in a handful of widely scattered sites in Louisiana, South Carolina, and Florida.  The ornithologists couldn’t stop final dissolution of the old growth forests at these sites.  Researchers have been unable to support a recent claim that the species had been rediscovered in Arkansas.  Scientists from Cornell University should be ashamed of themselves for publicly announcing the false rediscovery based on a grainy film of a bird, that looks to me, to be quite obviously a pileated woodpecker.

There were 2 species of large woodpeckers in the Campephilus genus.  Both required extensive tracts of virgin forest, both became extinct following the felling of these forests; and crackpot cryptozoologists still claim to see both of them in the woods on occasion.  Until hard evidence exists, I consider them long gone.

Historical range of the ivory-billed woodpecker.  It required large tracts of virgin bottomland forest to survive.

The ivory-billed woodpecker inhabited river bottomland swamps in southeastern North America.  Although they often nested in cypress swamps, they foraged in adjacent river bottomland hardwoods dominated by sweetgum and oak.  Bottomland hardwoods grow on higher terraces than cypress swamps and are only flooded for a short time of the year.  Ivory-bills were the largest and strongest woodpeckers north of the Rio Grande.  They specialized in foraging on trees that recently died, and this is part of the reason they became extinct.  Between 1880-1950 loggers clear cut almost all of the bottomland forests in the south.  Clear cutting created a landscape devoid of trees dead for 2 years or less.  Ivory-bills occupied a narrow niche requiring vast acreages of virgin forests disturbed here and there by storm and fire.  In the disturbed areas they could find lots of freshly killed trees.  They shredded the bark more efficiently than other species of woodpeckers because they were so much larger and stronger.  They were able to exploit the wood-boring beetle grubs that increased in density approximately 2 years after wood dies.  The beetle grubs would concentrate between the bark and sapwood, near the surface of the snag or log.  These wood-boring beetle grubs were the most important part of the ivory-bill’s diet which they supplemented with insects, fruit, and nuts.

Wood-boring beetle grubs only persisted near the surface of the dead log for about 2 years.  Eventually, other species of wood-boring beetle grubs penetrated deeper into the wood.  Smaller species of woodpeckers continued to forage on these rotting pieces of wood which last for about 10 years, but ivory-bills abandon the food source, even though they’re capable of boring that deep with their powerful bills.  This niche specialization explains why ivory-bills became extinct, while pileated and red-bellied woodpeckers still persist.  Older dead wood is just more common than fresh dead wood.

Ivory-bills were always a rare bird, consisting of low population densities.  James Tanner, who wrote the below referenced book, estimated that in a virgin bottomland forest there were 126 red-bellied woodpeckers and 36 pileated woodpeckers for every 1 ivory-billed woodpecker.    Incidentally, virgin forests have much higher woodpecker populations overall than second growth forests, supporting an estimated 3-6 pairs of pileated woodpeckers per square mile compared to less than 1 pair per square mile in second growth.  Woodpeckers must have dead standing wood.

Comparison between ivory-billed woodpeckers and other birds it may be confused with, especially the pileated woodpecker.  The ivory-bill is larger than the pileated and has white on its backside whereas the pileated has black on its backside.  I don’t know the original source of this excellent field guide but I found it on google images.

Ironically, museum collectors may have eliminated any chance that ivory-bills could have survived the destruction of their habitat.  In the bird’s last remaining refuges museum collectors simply wiped out the final populations, including one collector who in 1892 slaughtered the entire population along the Suwannee River in Florida.

Because the ivory-billed woodpecker was always a rare bird living in low population densities, I thought it would be invisible in the fossil record.  I was surprised to learn that scientists have identified fossil remains of this genus in Texas (dating to the early Pliocene) and Florida (dating to the Pleistocene).  Archaelogical evidence from American Indian sites has turned up ivory-bill material from Georgia and West Virginia to Colorado, the latter two sites far outside their natural range.  The Indians considered the ivory bills and the crowns of the birds to be valuable ornaments, and they were traded widely.

Scientists have even analyzed mitochondrial DNA from museum specimens of these birds.  Scientists differentiate two subspecies of ivory-bill: one lived in southeastern North America, and another lived in Cuba.  From the mtDNA evidence, scientists determined the two subspecies diverged ~1 million years ago.  Ivory bills must have reached Cuba during a glacial cycle when sea level fell and the land masses of Florida and the Yucatan penninsula were much closer to that island than they were during later interglacials.   As the sea rose during an ancient interglacial, the two populations became genetically isolated.  The large imperial woodpecker of Mexico (Campephilus imperialis) is closely related to the ivory-bill.  During the early Pliocene the imperial woodpecker and the ivory-bill likely diverged from a common ancestor that lived in a  range that was originally continuous.  The former became genetically isolated in montane forests of Mexico while the latter ranged in bottomland swamps.

Mounted specimen of the extinct imperial woodpecker, a close relative of the ivory-bill.  It looked very similar but was even larger…the largest woodpecker on earth.

Click on the following link to listen to the only existing recording of an ivory-billed woodpecker call.


Fleischer, Robert C.

“Mid Pleistocene Divergence of Cuban and North American Ivory-billed Woodpeckers”

Biology Letters (Available online)

Tanner, James

The Ivory-Billed Woodpecker

Dover Publications (from a document originally published in 1942)


17 Responses to “The Extinct Ivory-billed Woodpecker (Campephilus principalis)”

  1. James Robert Smith Says:

    I have a couple of friends who are avid bird watchers. I always go to them whenever I have a question about birds and they’ve been right, so far. Both of them think that the Ivory bill is around. Apparently, the lowdown is that they are existing in several pockets of forest here in the deep South and that there have been quite a number of positive sightings, but that naturalists on a university level, and wildlife officials on local, state and national levels are intentionally suppressing the information to keep the birds safe by keeping their habitat unmolested by curiosity seekers.

    But generally I agree with you. I need to see to believe. Until there is credible hard evidence I will assume claims of their existence are your neighborhood cryptozoologist at work.

  2. Mark Says:

    I think the field guide is from Cornell, but this is only a guess. I agree with JRS that seeing is believing, but if seeing is what is killing something to begin with (witness how ‘seeing ‘amphibians resulted in the extinction of many species through the spread of chytrid/Bd), then I’d rather just believe and not see. ‘Witnessing’ might be good in a biblical sense but can be deadly in a biological sense ….chytrid, possibly WNS, etc. as we trudge through our environments with all our viral and fungal baggage in tow. I’m not so sure the IBWO isn’t a lazarus species and may reappear miraculously…one more reason to call it the Lord God bird. You just never really know.

  3. cyberthrush Says:

    virtually NO chance that academic or wildlife officials are suppressing the existence of Ivory-bills for ‘safety’ purposes… such officials have been embarrassed mightily by the events of the last 6 yrs. (and money spent) and would like nothing better than to vindicate themselves with documentation of the species persistence.
    I still believe, considering all the evidence, that probabilities favor the continued existence of a few Ivory-bills, but proving it beyond doubt to a cynical audience may never happen.

  4. J. Says:

    Living in the Imperial Woodpecker’s former land is kind of heart breaking; every time I go out to the woods I look up to the trees hoping to catch a glimpse of one. I know it’s a fantasy, but one can dream…

  5. markgelbart Says:

    Click on the link under my blog roll entitled birdchick. On her blog she has the only film footage ever taken of an Imperial woodpecker.

  6. lauraswall Says:

    When I was in college, about 25 years ago, I lived off campus in the woods close to a creek. I saw an enormous woodpecker bouncing around about 20 feet from my window. It was at least 2 feet tall if not more. I just sat and watched him in amazement. It had too much white along his body to be a Pileated. I so wish I had a camera at the time! I m now an avid bird watcher and just can’t figure out what bird I was watching since the only possibility is considered extinct.

  7. cyberthrush Says:

    Laura, assuming it was a woodpecker, it was almost certainly a Pileated — they can flash a lot of white from underneath when they are “bouncing around” (it could also be a “leucistic” Pileated which would have even more white on it than a normal one).

  8. cyberthrush Says:

    if it was actually 2 ft. tall Laura, that is TOO large even for an Ivory-billed Woodpecker, but folks often describe Pileateds, Barred Owls, and other birds as “2 ft. tall” just because that is the impression they give compared to common forest birds. At 2 ft.+ you’re into the realm of small herons and large raptors. But the single biggest problem is just that (as you note) there is simply no historical record of Ivory-bills anywhere near that location (and completely out of range for Imperials).

  9. markgelbart Says:

    I second cyberthrush’s contention that you saw a pileated.

    Studies prove that most people inaccurately estimate sizes of animals when they view them from any distance.

    Unless you measured the specimen with a tape measure, any size estimate is unreliable.

  10. lauraswall Says:

    Thanks for all of your input. Realistically I know you’re right. But still, in the back of my head, I’m thinking what if.

  11. Alton Says:

    I live in SouthCentral Texas and for the past year been having trouble with bore beetles killing a lot of my oak trees. And have been seeing this giant woodpecker in my back yard. I have gotten a few photos of him but can’t really tell if he’s a pileated or not. Seen him flying this morning and he has a lot of white on his wings. I am now always ready with camera to try and get a positive I.D

  12. Jackie Boyt Says:

    I live in Louisiana and have seen the pileated and the ivory bill here. They are amazingly beautiful birds. But it seems like the plieated is the only one who is not camera shy. There are so many untouched by man miles of area around here. It amazes me how much we can treck through the woods and find. It breaks my heart everytime another area gets cleared out.

  13. kiletchia Says:

    I seen a bird today 4/19/2013 that looks just like the ivory billed woodpecker but I wasn’t close enough to see the Bill I live in cordele

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