Ivory-billed woodpecker

Name and taxonomy

Mark Catesby illustrated the bird in his natural history of Carolina, Florida and the Bahamas in 1731. Linnaeus used that account in 1758 and gave the species the name Picus principalis. George Robert Gray set up the genus Campephilus in 1840 with this bird as its type. The common name points at the bill, which is ivory white in an adult. The International Ornithologists' Union settled on ivory-billed woodpecker as the official English name.

Two subspecies are recognised, one in the southeastern United States and one in Cuba. The Cuban bird is a little smaller, and Brewer and Ridgway pointed to two feather differences in 1874. Some workers argue that the Cuban bird deserves species rank of its own. The American Ornithologists' Union has said that more testing is needed before it makes that split. Older country names include Log God, Kent, Poule de Bois in Cajun French and Tit-ka in Seminole.

Evolution and relatives

Campephilus is a genus of big woodpeckers spread across the Americas. A DNA study in 2006 compared the American bird, the Cuban bird and the imperial woodpecker of Mexico. The three proved genetically distinct, and together they form a North American group inside the genus. The study placed their split in the middle of the Pleistocene. It also hinted that the Cuban bird sits closer to the imperial woodpecker than to the American one. The imperial woodpecker of western Mexico is larger still, and it is probably gone as well.

The pileated woodpecker shares the range and much of the look, but it belongs to a different genus. The resemblance is close enough that most modern reports of ivory-bills turn out to be pileated birds. Like other members of its genus, the ivory-bill answers a rival with a sharp double rap.

Appearance

An adult measures 48 to 53 cm long, with a tail of 14 to 17 cm. The wingspan is about 76 to 78 cm, and body weight runs from 450 to 570 g. Those weights come from a handful of specimens, so they are a thin figure. Males run slightly larger than females. The body is shining black with a blue or purple sheen in good light.

White lines run from each cheek down the neck and meet on the back. The inner flight feathers are white, so a perched bird shows a white triangle low on its back. In flight the trailing edge of each wing is broadly white above and below. The bill is straight and heavy, and its tip is flattened sideways like a wood chisel. The iris is pale lemon yellow, and white feather tufts cover the nostrils against flying chips.

The crest is pointed and stands up when the bird is alert. A male has a black front edge to the crest and red on the side and rear. A female has a crest that is black all over, and so does a young male. A juvenile has a ragged crest and a chalky white bill rather than a polished one. Observers described the flight as strong, straight and duck-like.

Habitat and range

The species needs a wide, unbroken forest with big trees and a steady supply of dying ones. It used bottomland hardwood forest of sweetgum, oak, green ash, sugarberry and American elm. It also used bald cypress swamp and, before the loggers came, upland pine. Cuban birds lived in pine and hardwood forest and nested in large dead pines. Open canopies matter, because a bird of this size needs room to fly between trunks.

Edwin Hasbrouck drew the first range map in 1891, and James Tanner drew a second in 1942. Both drew a range reaching from east Texas across to the Carolina coast, and north as far as southern Illinois. The birds kept to low ground, roughly below 30 m above sea level. Scattered records lie outside both maps, including bones from mounds in Georgia and Ohio. Thomas Jefferson listed the bird among the birds of Virginia, under the name white bill woodpecker.

Numbers were always thin, because each pair worked a large area. Along the Tensas River, Tanner counted about one pair for every 44 square kilometres of forest. He found denser ground in Florida, with a pair for every 16 square kilometres on the Wacissa River. GBIF holds records from 4 countries, and almost all of them are old museum specimens.

Diet and feeding

About half of the stomach contents on record were large beetle grubs. Most came from longhorn beetles of the family Cerambycidae, which tunnel under fresh dead bark. Bark beetles, click beetles, jewel beetles and tree-dwelling termites also turn up in the records. The bird works a dying trunk by driving its bill under the bark and levering slabs of it away. That exposes the grub tunnels underneath, and the long barbed tongue lifts the grubs out.

No other bird in the range could peel tight bark that way, so competition for the grubs was slight. The other half of the diet was plant food, mostly nuts and fruit. Recorded items include pecans, hickory nuts, acorns, poison ivy seeds and southern magnolia fruit. Birds were also watched eating wild grapes, persimmons, hackberries and cherries. They sometimes dropped to the ground or to fallen logs to hunt insects in a burnt patch.

Behaviour and social life

The ivory-bill is active by day and sleeps alone in a roost hole it cut itself. Birds leave the roost near dawn and feed hard through the early morning. Activity falls away around midday and picks up again in the late afternoon. Each bird returns to its roost hole at dusk, and it often uses the same hole for a long time. Much of what is known comes from Tanner, who watched a few birds on the Tensas River in the 1930s.

A pair holds a home range rather than a defended territory. Birds have been tracked feeding up to 4 km from the nest, which gives a range of about 50 square kilometres. A Cuban study put the figure nearer 65 square kilometres. Ivory-bills tolerate each other, and no record describes one driving another off. Groups of four or five have fed in one tree, and eleven birds were once counted in one place.

They do not migrate, and pairs nested within a few hundred metres of an old nest year after year. Writers still call the species nomadic, because birds moved to fresh windfall, burns and flood damage. Dead wood of that kind fills with beetle grubs within a season or two. They also fed beside pileated woodpeckers without any sign of a quarrel.

Communication and senses

The best known call is a nasal kent, which listeners compared to a note from a tin trumpet. A disturbed bird raises the pitch, doubles the note and repeats it faster. A pair at the nest swaps a softer version back and forth through the day. Four calls are described in the old literature, and only two were ever recorded, in 1935. Family members trade notes while they feed and fall quiet towards evening.

The other signal is a drum, delivered as a single or double rap on a hard trunk. In the double rap the first blow is louder, so the second sounds like an echo. The male's red crest is a bright flag at close range, though its exact use was never studied. Like most birds, the ivory-bill probably relies on sharp eyesight and good hearing. Both kinds of signal have caused trouble for searchers. Blue jays and nuthatches make kent-like notes, and a flock of ducks can knock its wings like a drum.

Reproduction and life cycle

Pairs are thought to stay together for life and to travel as a couple all year. Breeding runs between January and May, and a pair raises one brood a year. A second clutch has only been seen after a first one failed. The two birds cut a nest cavity, usually 4.6 to 21.3 m above the ground. They favour a living or part-dead trunk and avoid rotten wood, which is too easy for a predator to open.

The hole is oval to oblong, about 12 to 14 cm tall and 10 cm wide. It usually sits under a broken stub, which shades the entrance and keeps the rain out. A typical cavity is about 50 cm deep, and the deepest on record reached 150 cm. Clutches of 1 to 6 eggs are reported, with an average near 2.7. The eggs are glossy and china white and average about 3.5 by 2.5 cm.

Tanner estimated an incubation period near 20 days, from a related species rather than direct counts. Both parents sit, the male through the night and the two in turn by day. Both parents then carry food, and feeding is heaviest in the first days after hatching. Young fly about 5 to 8 weeks after hatching and can feed themselves at three months. The parents keep feeding them for two more months, and a family may hold together for a year. No bird was ever followed to its death, and 15 years is a guess taken from its relatives.

Predators and threats

Nobody has ever recorded a wild animal killing an ivory-billed woodpecker. Birds did react to danger, and a pair once chased a Cooper's hawk away from the nest. A female called a warning and flew nearer her fledgling as a red-shouldered hawk came into view. Watchers also saw birds slip round the far side of a trunk when a raptor passed. Rat snakes, raccoons, squirrels and large owls may have taken eggs and nestlings.

The real threat was the axe and the saw. Timber companies cleared millions of acres of southern forest after the Civil War. That left small, separate patches, which cannot feed a bird with a home range this size. Shooting mattered too, for food, for curiosity and for museum drawers. Noel Snyder has argued that hunting, rather than logging, drove the first collapse.

Population and conservation

The IUCN rates the ivory-billed woodpecker Critically Endangered and marks it as possibly extinct. NatureServe treats it as presumed extinct, and the United States lists it as endangered from 1967. By the 1930s observers thought that fewer than 25 birds were left in the country. Tanner put the figure at 22 to 24 birds, with 6 to 8 of them on the Singer tract in Louisiana. Loggers finished the Singer tract by the late 1940s.

Don Eckelberry watched a bird there in April 1944, and that record is the last one everybody accepts. Cuban birds held on in the east of the island until at least 1987. Reports have never stopped, and several have brought searches, papers and arguments. A Cornell team filmed a large woodpecker in Arkansas in 2004 and identified it as this species. Other ornithologists read the same four seconds of video as a pileated woodpecker.

Teams in Florida, Texas and Louisiana have offered feathers, sound recordings and blurred film. In 2023 Project Principalis published trail camera pictures and drone video from a site in Louisiana. The team stopped short of calling the evidence conclusive, and critics read the birds as pileated. The Fish and Wildlife Service proposed declaring the species extinct in September 2021. After public comment it drew back, and in October 2023 it said it would keep reviewing the evidence. Habitat protection and forest restoration continue in the places where the bird might still hang on.

Relationship with humans

The bill was a valuable trade good long before Europeans reached the Mississippi. Bills and scalps travelled far outside the bird's range, some of them hundreds of kilometres. Catesby recorded a north to south trade in which one bill fetched two or three deerskins. European settlers hung dried heads on shot pouches or carried them as watch fobs. Some groups also ate the bird, and remains turn up in kitchen middens.

Hunting for food went on in the southeast into the 1950s, and fishermen used the flesh as bait. Collectors paid heavily for skins in the late nineteenth century. About 413 specimens sat in museums and universities as of 2007, over 60 of them at Harvard. The bird then became a prize for birdwatchers instead of a prize for gunners. Cornell offered 50000 dollars in 2008 for anyone who could lead scientists to a roost or nest.

The 2004 Arkansas reports sent visitors to Brinkley, where tourist spending rose by about 30 per cent. The town held a celebration for the bird in February 2006, with tours, talks and stalls. Access to about 5000 acres of refuge forest was closed to hunting and fishing. Local people worried about the closure, since hunting and fishing carry the local economy. Searching for the bird is probably a small industry of its own now.

In culture and myth

The bird carries more nicknames than almost any other American species. Lord God Bird is the best known, and it probably began as an exclamation at the size of the bird. Log God, Log Cock, Indian Hen and Kent all appear in older writing. Cajun French speakers called it Poule de Bois, the wood hen. Birdwatchers now call it the Grail Bird, because so many have looked and none have proved it.

Native American nations used the bill and the scalp in ceremony across a wide area. Bills marked with red pigment lay among grave goods at an Omaha village. The Iowa people worked bills and scalps into ceremonial pipes. The Sauk and the Meskwaki placed the same parts in amulets, headbands and sacred bundles. Because the bills carried this weight, they probably signalled rank as well as skill in war.

John James Audubon called it the great chieftain of the woodpecker tribe. William Faulkner named it in his 1942 novella The Bear as a bird of the old Mississippi woods. Eudora Welty wrote about its loss in an essay in 1944. Sufjan Stevens wrote a song about it after the Arkansas reports, and it went out on public radio. Arkansas has printed the bird on a car number plate. A painting by Joseph Bartholomew Kidd, taken from Audubon, hangs in the Metropolitan Museum of Art.