Video analysis of the escape flight of Pileated Woodpecker

Background: The apparent rediscovery of the Ivory-billed Woodpecker Campephilus principalis in Arkansas, USA, previously feared extinct, was supported by video evidence of a single bird in flight (Fitzpatrick et al, Science 2005, 308:1460–1462). Plumage patterns and wingbeat frequency of the putative Ivory-billed Woodpecker were said to be incompatible with the only possible confusion species native to the area, the Pileated Woodpecker Dryocopus pileatus. Results: New video analysis of Pileated Woodpeckers in escape flights comparable to that of the putative Ivory-billed Woodpecker filmed in Arkansas shows that Pileated Woodpeckers can display a wingbeat frequency equivalent to that of the Arkansas bird during escape flight. The critical frames from the Arkansas video that were used to identify the bird as an Ivory-billed Woodpecker are shown to be equally, or more, compatible with the Pileated Woodpecker. Conclusion: The identification of the bird filmed in Arkansas in April 2004 as an Ivory-billed Woodpecker is best regarded as unsafe. The similarities between the Arkansas bird and known Pileated Woodpeckers suggest that it was most likely a Pileated Woodpecker. Background The reported rediscovery of the Ivory-billed Woodpecker in 2004–5 in the Big Woods of Arkansas gave new impetus to efforts to conserve the mature bottomland woodlands of the south-eastern USA. Several sightings have been reported without photographic evidence being obtained [1]. Unless sightings are, however, independently verifiable on the basis of photographic or other recorded evidence, the possibility that mistakes have been made cannot be eliminated. Crucial to the scientific case for the persistence of the Ivory-billed Woodpecker was a 4 s video of a large woodpecker in flight recorded by M.D. Luneau on 25 April 2004 (henceforth referred to as the 'Luneau video') and published in 2005 [1], which was claimed to be inconsistent with the plumage patterns of the superficially similar Pileated Woodpecker (a common resident bird of the area). Both species are large, blackand-white woodpeckers [2]. The upperwing of the Ivorybilled Woodpecker is black, with white secondary feathers and white on some inner primary feathers. Pileated Woodpeckers have a largely black upperwing, with white restricted to the 'wrist' due to white bases to the primary feathers. The underwing of Pileated Woodpecker has allwhite underwing coverts, giving an appearance of a white underwing with a broad black outline (the black flight feathers). These plumage differences result in the IvoryPublished: 15 March 2007 BMC Biology 2007, 5:8 doi:10.1186/1741-7007-5-8 Received: 7 August 2006 Accepted: 15 March 2007 This article is available from: http://www.biomedcentral.com/1741-7007/5/8 © 2007 Collinson; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.