title: Video analysis of the escape flight of Pileated Woodpecker Dryocopus pileatus: does the Ivory-billed Woodpecker Campephilus principalis persist in continental North America?
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: University of Aberdeen, School of Medical Sciences, Institute of Medical Sciences, Foresterhill, Aberdeen, UK. m.collinson@abdn.ac.uk
authors.forename: J Martin
authors.initials: JM
authors.lastname: Collinson
mesh_terms: D000818:Animals; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology*; D003247:Conservation of Natural Resources; D004463:Ecology; D004777:Environment; D005260:Female; D005426:Flight, Animal; D008297:Male; D008954:Models, Biological; D009656:North America; D013045:Species Specificity; D014741:Video Recording; D014921:Wings, Animal / Q000033:anatomy & histology / Q000502:physiology