| Ivory-Billed Woodpecker (1838)|
by John James Audubon
|Conservation status||Critical |
The Ivory-billed woodpecker (Campephilus principalis), also called Ivory-bill or the Grail bird, was once endemic to the southern United States until being declared extinct in the 1970s. The species' 2004 rediscovery in the Cache River National Wildlife Refuge in Arkansas created a sensation worldwide.
The Ivory-bill is crow-sized, with mostly black plumage, which can be a glossy blue-black, especially on wing-coverts; outer primaries and tail are a duller black. Males have red crest, two broad white stripes on each side of the head extending from below the eyes down the sides of the neck and onto the back, merging with a broad white “shield” created by the white inner primary and all secondary wing feathers when the wings are folded over the back. The female is similar to the male but slightly smaller, with an all-black crest. Both sexes have the characteristic ivory-colored bill. Juveniles similar to adults of each sex but somewhat browner and with somewhat rounded tip to bill (especially from above) and shorter crest.
The Ivory-billed Woodpecker historically preferred expansive patches of mature forestland, often with embedded patches of recently disturbed forest from hurricanes, tornadoes, fire, insect outbreaks, and to some degree logging as long as some damaged trees were left standing. Its’ diet is known to be largely dependent on wood boring beetle larvae found in recently dead and dying trees. The bird uses its enormous white bill to hammer, wedge, and peel the bark off recently dead and dying trees to find the insects. This species is unique among woodpeckers in being able to pull out the beetle larvae that are close to the interface between freshly dead sapwood and the tight bark (usually too tight for any other woodpeckers to pry loose). During some times of the year the species feeds on fruit and other vegetable matter.
Like all woodpeckers, the Ivory-bill is a cavity-nester. In the Mississippi Delta, it is known to nest in a variety of hardwood and cypress trees while in other areas throughout its’ historic range, including Cuba, it also nested in mature pines. The species has an extraordinarily large home-range, and it has been estimated that one pair of Ivory-billed Woodpeckers need 6 to 10 square miles or more of habitat. The larger the home range, the less quality habitat there may be to support a pair.
Pairs are thought to mate for life and are also known to travel together. These paired birds will mate every year between January and May. Before they have their young, they excavate a nest in a dead or partially dead tree about 8–15 meters up from the ground. Usually three eggs are laid and incubated for 3–5 weeks. Both parents sit on the eggs and are involved in taking care of the chicks, with the male taking sole responsibility at night. They feed the chicks for months. About five weeks after the young are born, they learn to fly. Even after the young are able to fly, the parents will continue feeding them for another two months. The whole family will eventually split up in late fall or early winter.
Ivory-bills inhabited large blocks of mature forests in the southeastern and Lower Mississippi Valley states: from North Carolina to Florida and west to eastern Texas and Arkansas. They also occurred in Cuba. Ornithologists believe that the species was never abundant since populations were limited by the availability of dying and recently dead trees for foraging, roosting, and nesting.
The Ivory-bill’s precipitous decline began in the latter half of the 19th century as forests were cleared for settlement and agriculture. Technology and the resource demands of two world wars increased the logging rate in the 20th century, further decimating habitat. In addition to excessive tree harvest, excessive collection of birds for commercial, recreational, scientific, and educational purposes also contributed to declines as the range became restricted.
By 1939, James Tanner estimated that 22–24 birds remained in the U.S. Today, only widely scattered, large remnants of mature, seasonally flooded forest provide potential habitat. Reforestation that has been occurring on public and private lands over the past two decades should provide more habitat as stands mature.
Post 1940s sightings
The last widely accepted sightings of the Ivory-billed Woodpecker in the United States were those that took place at the Singer Tract. However, there have been numerous intriguing reports if ivory-bills since that time.
John Dennis was a prominent woodpecker biologist who in 1948 snapped the last scientifically accepted photographs ever taken of an ivory-bill in Cuba. In 1966, Dennis reported seeing a female ivory-bill in The Big Thicket of east Texas, but his sighting could not be confirmed by subsequent searchers. While other promising reports, including fleeting glimpses and possible calls, have come from a variety of places, until the 2004 Arkansas sightings, no sightings have resulted in conclusive physical evidence.
A kayaker in the Cache River National Wildlife Refuge in Arkansas reported seeing a big woodpecker fly over him; his description of the bird caused Cornell University and the Nature Conservancy to mount an expedition to the area; their subsequent video footage and recordings of the bird's distinctive "double-knock" when it probes for insects resulted in millions of dollars in Federal grants for the ivorybill's study and protection, as well as the purchase of more than 18,000 acres of land adjacent to the Cache River.