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:An Alternative Hypothesis for the Cause of the Ivory-billed Woodpecker's Decline

2008; Oxford University Press; Volume: 110; Issue: 4 Linguagem: Inglês

10.1525/cond.2008.8658

1938-5129

Geoffrey E. Hill,

Viral Infections and Vectors

It is human nature to want simple answers to complex questions.If the easy answer also carries a broader message, then it becomes nearly irresistible.The correctness of the answer can become completely secondary to the heuristic power of the argument and the lesson that is being taught.Why did Ivory-billed Woodpeckers (Campephilus principalis) disappear from North American forests in the early 20 th century?The simple answer is that when the virgin forests on which the species depended were cut, these foraging specialists could not survive in the remaining second-growth forests and simply faded away.It's a good story, first told and expounded by James Tanner (1942), the foremost expert on these magnificent woodpeckers, who drew on his personal observations of ivorybills in Louisiana.It is a simple story-the huge woodpecker with a huge bill needed huge trees.And it is a story that carries a critical conservation message-wanton destruction of native habitats inevitably leads to the extinction of species.This explanation for the demise of the ivorybill is so powerful that it stands virtually unchallenged from sixth-grade classrooms to the lecture halls of our most distinguished universities.Unfortunately, this explanation is at best incomplete and at worst totally inaccurate.In a methodical reassessment of the evidence, Snyder attempts to dismantle the argument that the cutting of virgin forest was the primary cause of the disappearance of the Ivory-billed Woodpecker.His alternative explanation is that the Ivory-billed Woodpecker disappeared in the late 19 th and early 20 th century primarily due to direct persecution by people.Put simply, Snyder contends that people shot virtually every Ivory-billed Woodpecker on the continent.Snyder develops his thesis on four fronts: (1) ivorybills are not foraging specialists, (2) ivorybills were, until the late nineteenth century, common rather than rare birds within their habitat, (3) ivorybills declined in and disappeared from many regions before virgin forests were cut, and (4) ivorybills were shot not simply by skin collectors but also much more extensively for food and sport.These four arguments converge on the central argument that there is substantial evidence that Ivory-billed Woodpeckers were shot to near extinction.Snyder includes assessments of Cuban as well as U.S. populations of ivorybills, but given recent analyses showing that Cuban birds are genetically distinct from U.S. birds (Fleischer et al. 2006), I'll focus this review on the portion of the book dealing with U.S. ivorybills.The argument against foraging specialization may be the argument that ivorybill enthusiasts will find most difficult to accept because it challenges one of the primary theses of the Ivorybilled Woodpecker Bible-James Tanner's 1942 monograph