stinctive call note, "kent", which is often described as sounding similar to a note from a tin trumpet or a New Year's Eve party horn. When pairs are together they utter somewhat softer call notes, and when more than two are together they engage in soft chatter or sometimes a chorus of long, upslurred notes. Family members trade call notes back and forth throughout the day as they forage, growing quiet towards evening. Ivory-billed woodpeckers also communicate by drumming their heavy bills on tree surfaces. Their distinctive drum sound is a double rap, the first rap slightly louder than the second, so that it sounds like the second is an echo of the first. Finally, the bright red crest of a male ivory-billed woodpecker sends a clear visual signal, and no doubt serves a communicatory function, but its exact purpose has not been studied. (Jackson, 2002)
Ivory-billed woodpeckers feed on large beetle larvae, which they find by stripping away the bark of dead or dying trees. Occasionally, they forage for insects on the ground in recently burned areas or in fallen logs. Insects consumed belong to the families Cerambycidae, Buprestidae, Elateridae, Scolytidae, Melasidae, and also include arboreal termites (Isoptera). However, insects only make up about half the diet; in addition, ivory-billed woodpeckers eat berries, nuts and seeds, including cherries, southern magnolia fruits and seeds, pecan nuts, hickory nuts, poison ivy seeds, grapes, persimmons, hackberries, and possibly acorns. (Jackson, 2002)
No one has ever recorded predation on ivory-billed woodpeckers, except for that by humans. Potential predators include raccoons, rat snakes, great horned owls, barred owls, Cuban crows, American crows, red-shouldered hawks, Cooper's hawks, and Stygian owls. There is a report of a pair of ivory-billed woodpeckers chasing a Cooper's hawk away from their nest while scolding it, and another report of a female ivory-billed woodpecker giving a warning call and flying closer to her fledgling when a red-shouldered hawk appeared in the area. There are also reports of ivory-billed woodpeckers rapidly switching to the other side of trees when birds of prey materialized nearby. (Jackson, 2002)
Thanks to their chisel-like bills, ivory-billed woodpeckers are potential ecosystem engineers. The tree cavities they excavate are probably used by an array of other species once the woodpeckers leave. These species might include wood ducks, eastern bluebirds, opossums, gray squirrels, and honeybees.
Because they share many similarities, some have suggested that ivory-billed woodpeckers compete with pileated woodpeckers for food and prime cavity sites. Competition between the two species may have intensified after forests were logged, with pileated woodpeckers, which adapt much more readily to human disturbance, being more successful. However, interactions between ivory-billed woodpeckers and other woodpecker species have never been directly studied.
Ivory-billed woodpeckers are predators of insects, but it is doubtful they have a huge impact on insect populations as their numbers are so low. Because they eat fruits and seeds, it is possible that ivory-billed woodpeckers disperse seeds.
Recently, researchers discovered a new species of feather mite on museum skins of ivory-billed woodpeckers. They named the new mite Pterotrogus principalis. This mite is the only known parasite of ivory-billed woodpeckers. (Jackson, 2002; Mironov, et al., 2005)
Ivory-billed woodpeckers have had economic importance to humans for centuries. Native Americans collected them for their bills, which symbolized successful warfare. American colonists traded with Native Americans for the bills, which they saw as a curiosity. Later, the heads of ivory-billed woodpeckers were sold as souvenirs and the bills were marketed as real ivory. In the late 19th century, collecting natural items became popular, and ornithologists paid dearly--$40 to $50 per bird--to add ivory-billed woodpeckers to their collections. In Cuba, humans sometimes ate ivory-billed woodpeckers or killed them for sport