To find out, the U.S. Fish and Wildlife Service ordered a multi-state, intensive search effort for the elusive bird and a population viability analysis, which, among other things, assesses the population size and other factors required for the population to persist over specified time frames.
Mattsson, a former doctoral student working with Cooper, took the lead on the modeling project by constructing the population model and conducting the analysis. Based on information gleaned from the literature and unpublished sources on closely-related species of woodpeckers, Mattsson considered plausible ranges of initial population size, reproduction rates and adult survival rates to play games of "what if" with simulated woodpecker populations. What he found was that as few as five breeding pairs of these large woodpeckers could have ensured the persistence of ivory-billed woodpeckers in wooded swamps of the southeastern U.S. to this day.
He said his model is not meant to prove their existence, but "it gives people involved with the research team hope that they're still out there," and shows that sufficient levels of reproduction and survival are as important, if not more important, than large numbers of individuals for ensuring persistence of the species.
Cooper said that initially it was thought that the ivory-billed woodpeckers had a very small chance of persisting through modern times, but he believes Mattsson's analysis shows that the probability is larger than originally suspected.
Conroy is optimistic about implications from their findings for similar species thought to have blinked out of existence.
"I think it gives us hope that remnants of [species] out t
|Contact: Sandi Martin|
University of Georgia