Why can’t it be an Ivory-billed Woodpecker?

Several plumage features in the Luneau video tell us that the bird cannot be an Ivory-billed Woodpecker. Figures below illustrate these features and compare them to video of Pileated Woodpeckers photographed and digitally processed in the same way as the Luneau video (see Video).

The Luneau video is very poor, with the image of a fleeing bird occupying just a few pixels. The bird is distant, out-of-focus, moving rapidly itself, and captured by a camera on a turning and rocking platform. Given the limited information discernible, I can understand why some people conclude the bird is simply unidentifiable. That is a reasonable position. Nevertheless, I think that if one takes the time to review the video thoroughly, as I have done with my colleagues, then I believe you will come to agree with our position that it is almost certainly a normal Pileated Woodpecker.

Is there a more robust approach to identification?

People tend to seek, and are excessively influenced by, evidence that supports their belief. This tendency to seek confirmatory features is a pitfall of bird identification, and is a fallibility exacerbated when evidence is ambiguous or lacking, as in the Luneau video. The misidentification of the Luneau bird exemplifies this problem. Many people and even some decision-making agencies, such as the U.S. Fish and Wildlife Service (see here), have placed too much weight on a supportive feature—that the bird appears to show more white than expected for a Pileated. A more secure approach to testing one’s identification is to look for characters that eliminate the proposed species. Following that approach, one sees several independent plumage features discernible in the Luneau video that eliminate Ivory-billed Woodpecker but not a normal Pileated Woodpecker.

            wingtip and underwing pattern                              brighter white wing patches

                 too little white in wing                                               black secondaries

              

—Bright white wing patches—

Would an Ivory-billed exhibit a wing pattern so similar to Pileated?

Luneau video: white arcs prominent; also           Pileated Woodpecker: at same distance

curved black wingtip. Note gray proximally          showing prominent white arcs in wing,

where wing coverts shaded (field 300).                grayer inner wing, and wide black wingtip.

Pileated Woodpecker: another individual           Pileated Woodpecker: another video field

exhibiting the same pattern.                                 of same bird as above.

Ivory-billed and Pileated Woodpecker wing patterns—specimen evidence

                            Dorsal wing surface                            Ventral wing surface

Ivory-billed Woodpecker (above) and Pileated Woodpecker (below): Ivory-billed Woodpecker lacks the prominent white patch at the base of the primaries (circled). This patch shows through dorsally in the Pileated Woodpecker. As a result, light passes through and forms a brighter white patch ventrally on the wing. Also note the very different wingtip pattern, with white extending to near the tip of the trailing edge of the wing on Ivory-billed, restricting the black to a narrow block on the forewing. By contrast, Pileated has black extending fully around the wingtip. Photograph modified from figure 4 in Capainolo et al. 2007, The Auk 124(2):705-709.

In a response to our critique that cited the presence of bright white wing patches in both the Luneau bird and Pileated Woodpeckers, Fitzptrick et al. (2007) stated that “an impression of brighter white near the primary bases is not diagnostic for pileated, as the primaries are also basally white in most ivory-billed woodpecker specimens.”

This is false and misleading. First, the brighter white patches are not merely an impression. They are consistent, obvious, and repeated in the Luneau video. Second, no Ivory-billed Woodpecker specimen shows broad white patches uncovered by overlying feathers dorsally, so that they create a translucent patch. The existence of this patch is diagnostic and eliminates Ivory-billed from consideration.

The assertion that this area of the underwing might be more reflective and thus appear as a brighter patch can be rejected because one sees the adjacent underwing coverts, which appear contrastingly grayer where light is blocked from shining through the wing. Additionally, the light conditions at the time were overcast, therefore no reflective highlight would be expected to occur.

—Wingtip pattern—

Luneau video: note curving black wingtip           Pileated Woodpecker: black wingtip similar;

apparently extending across inner primaries        border to trailing edge of wing blurs so that

on both the right (closer) and left wings.               it appears to be lacking.

Ivory-billed Woodpeckers have white on the inner primaries, resulting in a spread wing pattern where the trailing edge of white extends much closer to the distal portion of the wingtip than on Pileated Woodpecker (see photo of spread wings, above). This would produce a pattern with black restricted to a smaller area at the leading edge of the wingtip than seen on the bird in the Luneau video. The assertion that the black portion of the wingtip on an Ivory-billed would blur to produce a pattern with black appearing to extend to the inner primaries is untested and unverified. By contrast, my video of similarly distant and blurred Pileated Woodpeckers shows a pattern very similar to the Luneau bird (shown here; also see above under ‘Bright white wing patches’).

—Black secondaries—

Luneau video: video fields 350 (left) and 466.7 (right). On the left, note the black arc to the left of the white patch. This black arc is best interpreted as the dorsal surface of the secondaries on the bird’s left wing. The all white secondaries of an Ivory-billed would never show this. On the right inside the circle, note the gray tree trunk across which the black arc extended in the left-hand frame. This confirms that the black we see is not background shadow. The intensity and solid nature of the black arc is unlike any darker edge effect, which one can see around tree trunks and other parts of the bird itself (also compare to other images from the Luneau video on this page). Note that in the upper right of each frame, a dark shadow in the background may be mistaken as the leading edge of the wing when it appears behind the bird as in the right-hand frame (field 466.7).

Two deinterlaced video fields magnified 10x and showing the apex of the wingstroke in two successive wingbeats (from original video by D. Luneau). Ivory-billed Woodpecker has gleaming white secondaries and inner primaries; therefore the appearance of black secondaries at any stage of the wingbeat cycle eliminates that species. This black is consistent with Pileated Woodpecker. In their response, Fitzpatrick et al. (2006) did not address this critical feature. Instead, they discussed ambiguous edge effects and suggested that we (Sibley et al. 2006) were misinterpreting those as a black trailing edge to the wing. As shown on this page, live Pileated Woodpeckers video taped under the same conditions do not always show a dark trailing edge to the underwing. Regardless, the feature pointed out here is the black secondaries as seen dorsally, not ventrally.

—Too little white in wing—

Luneau video: middle of upstroke.                     Pileated Woodpecker: middle of upstroke.

Only two white patches; too little white.               Only two white patches; similar pattern.

The one in seven video fields that show the Luneau bird in upstroke show a bird that is mostly dark, as would be expected—and here confirmed—for a Pileated Woodpecker. Indeed, if one lines up the Luneau video frames so that the same stage of the wingbeat cycle can be compared across successive wingbeats, one finds this mostly dark “ball” a consistent feature. The gleaming white secondaries and inner primaries of an Ivory-billed would not appear dark at any stage of the wingbeat cycle. The much slower downstroke phase, six of seven video fields, also explains, in part, the predominance of white seen in the Luneau video and similarly positioned Pileated Woodpeckers flying nearly directly away and rising above the level of the camera. This means that the white underwing predominates in caudal view.

—Underwing pattern—

Luneau video: note white underwing                 Pileated Woodpecker: note entirely white

lacking a broad dark wedge across                     underwing typical of this species videotaped

underwing. Also compare with frame                  at this distance with same camera settings.

above under “Wingtip Pattern.”                           (Arkansas trees superimposed.)

Wooden model used in reenactment:                        Ivory-billed Woodpcker:

wing stripe too narrow and too abruptly tapered;           wing stripe broad and tapers gradually;

opaque, rigid model not a realistic comparison;            width 2.4 to 9.5 cm, or 16%, 25%, & 37%

swept-back wing profile unrealistic.                               of total wing breadth at inner, middle, outer.

(figure 2B, Fitzpatrick et al. 2006, Science)                   (male; ANSP 108405; ph. courtesy N. Rice)

Note: the specimen spread wings shown here are of two different individuals; the wing below, at AMNH, lacks bones, whereas the one above, at ANSP, has the wing bones intact.

Female Ivory-billed Woodpecker in flight (left), spread wing (right): note straight wing profile and broad black wedge across underwing. The breadth of the black wing stripe is 15%, 25%, and 40% of total wing breadth at inner, middle, and outer points, corresponding to same measurements taken on the ANSP specimen above. Female Ivory-billed, April 1935, Singer Tract, Louisiana (A. A. Allen and J. T. Tanner). Here photographed directly from a printed copy of The Auk 54 [2],1937, plate 13, opposite pg. 176. Right: another spread wing of Ivory-billed Woodpecker for comparison; this photograph modified from figure 4 in Capainolo et al. 2007, The Auk 124(2):705-709.

Where is the huge black wedge?

It’s not there. An Ivory-billed Woodpecker would be expected to show this. Whereas video of Pileated Woodpeckers confirms that the black trailing edge may disappear, what about the broad black wedge on the underwing of an Ivory-billed? This broad black stripe, constituting up to 40% of the wing breadth, is unlikely to disappear. At a minimum, its presence would be expected to result in a different wing pattern than seen on the bird in the Luneau video.