The rediscovery of the Ivory-billed Woodpecker opened up the possibility of expanding our knowledge of this poorly studied species. The videos that were obtained in Louisiana and Florida show behaviors that don’t appear in a film that was obtained in 1935 (no flights appear in that film).

Mechanics of Double Knocks. Most woodpeckers signal with drumming, but the Ivory-billed Woodpecker and some of the other members of the Campephilus genus signal with double knocks. While studying footage of an Ivory-billed Woodpecker delivering a blow that is accompanied by an audible double knock, I noticed that there appears to be only one thrust of the body. This didn’t seem to be consistent with my expectation that a double knock is the result of two deliberate blows. While studying video footage of a Pileated Woodpecker drumming, I noticed something that led to an understanding of double knocks and how they relate to the drumming that is typical of most woodpeckers. As discussed in Movie S1 of this article, the drumming of a Pileated Woodpecker is driven by periodic vibrations of the body, and there are a few additional blows of decreasing amplitude after the driving force is turned off. This suggests that a drumming woodpecker may be modeled as a harmonic oscillator in which the bird is anchored with its feet and tail and the restoring force corresponds to tension in the neck and body. The graph on the above left corresponds to a damped harmonic oscillator in which periodic forcing is turned on at the first dashed line and turned off at the second dashed line. After a brief transient, the response is periodic. After the forcing is turned off, there is a transient that is consistent with the observed drumming of a Pileated Woodpecker. The graph on the above right corresponds to a damped harmonic oscillator with impulsive forcing. The response is a transient similar to the one appearing to the right of the second dashed line in the graph on the above left. This model accounts for (1) the double knock in the 2007 video, (2) the double knock of a Pale-billed Woodpecker that is discussed in Movie S2 of this article, and (3) the multiple knocks of some Campephilus woodpeckers, such as those of a Crimson-crested Woodpecker in this audio recording and this video.

Flights of the Ivory-billed Woodpecker. According to the great naturalist, John James Audubon, the flight of the Ivory-billed Woodpecker is “graceful in the extreme.” This account indicates that there must be something extraordinary about the flights of this bird, but for several decades it appeared that specific details about the types of flights that inspired the account were lost forever. Since no flights appear in the film that was obtained at one of the last known nests in 1935, historical accounts were until recently the only information that existed about the flights of the Ivory-billed Woodpecker. Several types of flight appearing in the videos may be viewed in movies that accompany the up-to-date summary. Michael DiGiorgio produced the above illustrations of flights (click here for a high-resolution version).

Swooping Flights. As shown in the illustration on the left, the Pileated Woodpecker typically swoops upward a short distance before landing on a surface that faces the direction of approach. In the 2007 video, there are spectacular upward swooping landings with long vertical ascents, which are consistent with an account by Eckelberry of an Ivory-billed Woodpecker that “alighted with one magnificent upward swoop.” A long vertical ascent allows time for maneuvering. As shown in the illustration on the left, during two upward swooping landings in the 2007 video, there is a long vertical ascent, rotation about the axis, and landing on a surface that does not face the direction of approach. A Magellanic Woodpecker makes the same flight maneuver in this video, which was obtained in Patagonia in 2025. This is a clear match of a remarkable behavior by a closely-related Campephilus woodpecker that cannot be attributed to the Pileated Woodpecker. A downward swooping takeoff that is followed by a long horizontal glide in the 2007 video is consistent with the following account by Audubon: “The transit from one tree to another, even should the distance be as much as a hundred yards, is performed by a single sweep, and the bird appears as if merely swinging from the top of the one tree to that of the other, forming an elegantly curved line.” As shown in the illustration in the middle, a woodpecker in the 2007 video takes off and accelerates with rapid wingbeats into a remarkable high-speed upward swooping flight immediately after delivering a blow that produces an audible double knock.

Cruising Flight. The Ivory-billed Woodpecker has a ‘duck-like’ flight according to historical accounts, which were incorrectly interpreted to pertain to the wing motion. In the September/October 2005 issue of Bird Watcher’s Digest, the flights of the large woodpeckers are illustrated in a series of paintings by Julie Zickefoose (an avian artist whose work on the Ivory-billed Woodpecker has appeared on the cover of the January 2006 issue of The Auk). Zickefoose correctly showed the wings of the Pileated Woodpecker folding closed during the middle of the upstroke (this wing motion is apparent in this footage). In accordance with conventional wisdom at the time, Zickefoose showed the wings of the Ivory-billed Woodpecker remaining extended throughout the entire flap cycle. After the 2008 video revealed that the wing motion of the Ivory-billed Woodpecker is similar to the wing motion of the Pileated Woodpecker (as shown in the right frame of the illustration above), it came to light that a photo from 1939 was taken at an instant when the wings were nearly folded closed. This is one of the lowest quality historical photos, and the clue it provides about wing motion was apparently overlooked for several decades. The description of a duck-like flight evidently pertained to the high-speed flight rather than to the wing motion. The bird in the 2008 video has a flight speed of 15.2 m/s, which is well above the flight speed range of 7.5 to 11.6 m/s that Bret Tobalske published for the Pileated Woodpecker. The bird in the 2008 video has a wingbeat frequency that is about double the wingbeat frequency that Tobalske published for the Pileated Woodpecker. The high flight speed and high wingbeat frequency are consistent with historical accounts, the narrow wings and high mass of this species, and the predictions of models that relate these quantities to each other and to body parameters. The wings of the bird in the 2008 video have a swept-back appearance, which is consistent with a photo from 1935 and the narrow wings and high-speed flight of this species. The wings of the Pileated Woodpecker do not seem to have a swept-back appearance during cruising flight.

Short Flights between Limbs. According to an account by Tanner, the Ivory-billed Woodpecker usually flaps its wings during short flights between limbs. This would make sense for a woodpecker that has narrow wings and is one of the most massive in the world. The Pileated Woodpecker has a relatively low mass and broad wings, and it makes short flights nearly effortlessly. The large woodpecker in the 2006 video makes a deep and rapid flap during a flight of less than one meter. According to Zickefoose, this flight is “unlike anything I’ve seen a Pileated Woodpecker do.”

Takeoffs with Deep and Rapid Wingbeats and ‘Wooden’ Wing Sounds. According to historical accounts, the Ivory-billed Woodpecker has deep and rapid wingbeats during takeoffs. This would make sense for a massive woodpecker with narrow wings. According to Tanner, the wings make loud ‘wooden’ sounds during takeoffs with deep and rapid wingbeats. In the 2007 video, there are loud wooden wing sounds during two takeoffs with deep and rapid wingbeats. During one of those takeoffs, the deep and rapid wingbeats are similar to the deep and rapid wingbeats during a takeoff of the closely-related Imperial Woodpecker; the Pileated Woodpecker has much slower wingbeats during takeoffs. Just before the other takeoff with deep and rapid wingbeats, the bird came in for a landing with a magnificent upward swoop and showed field marks consistent with the Ivory-billed Woodpecker.

Using the Wings for Balance. According to Tanner, the Ivory-billed Woodpecker frequently ‘flirts’ its wings (rapidly opens and closes them). This behavior would make sense for a massive woodpecker that uses its wings in order to maintain its balance while moving around in a tree. In some cases, flirting the wings could be regarded as a type of flight in which the wings are used for balance rather than to become airborne. An Imperial Woodpecker (the most massive woodpecker in the world) flirts its wings in the only 85 seconds of film that exists of that species. Just before delivering a blow that produces a double knock in the 2007 video, the bird flirts its wings several times while moving along a branch.