Fitzpatrick says his team isn't surprised by the nay-saying.
"Scrutiny of evidence is a natural and desirable process in science," he told National Geographic News. "The video is blurry and imperfect, so from the beginning we anticipated that debate might take place about the identity of the bird."
Fitzpatrick says he remains fully convinced that at least one ivory-bill was present in the study area in 2004 and early 2005. He adds that the team is following up on a number of new reported sightings.
"What everyone agrees on is that we need more information," Fitzpatrick added. "We will be working again intensively the Big Woods this fall, winter, and the coming spring."
Fitzpatrick's sentiments are echoed by the Nature Conservancy (TNC), an international land-conservation nonprofit based in Arlington, Virginia. TNC is closely involved in protecting and restoring habitat in the Big Woods region.
"News of the ivory-bill's existence earlier this spring was one of the biggest scientific announcements in decades," said TNC spokesperson Karen Foerstel. "We expected people to be skeptical of the announcement."
"We and our partners stand by scientific evidence showing the ivory-bill still lives, and we are moving forward with our land-management and search plans."
The search for further evidence of the ivory-bill's existence will resume this fall, when reduced leaf cover and lower temperatures should assist researchers.
Since the search for the bird first began, a further 18,000 acres (7,300 hectares) of potential ivory-bill habitat has been protected. There are plans to conserve and restore an additional 200,000 acres (80,000 hectares) over the next ten years.
Along with the ivory-bill, Foerstel says eight other species listed as threatened or endangered by the U.S. government rely on the Big Woods for survival.
"The Big Woods is and will remain a priority for the Nature Conservancy," she said.
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