[TN-Bird] Re: Fw: [ia-bird] Re: Hooded Crane (speculative)

  • From: Bill Pulliam <littlezz@xxxxxxxxx>
  • To: kbreault@xxxxxxxxxxxxx
  • Date: Thu, 9 Feb 2012 15:17:42 -0600

The Indiana discussions have repeated what others have said, that they think the "null hypothesis" for the Hooded Crane should be "escapee." The more I have thought about it, the more I disagree with this. This is valid, in my view, IF the species is one that has a fairly large and/or poorly controlled captive population, or a species that does not have a history of long-distance natural vagrancy. Neither applies in the case of the Hooded Crane, as has been extensively discussed elsewhere. I don't think we have a "null hypothesis" for the origin of this bird, as neither scenario appears likely but one clearly did happen, and we are going to have to make an active decision one way or the other without being able to passively default to an a priori "conservative" stance.

Bill Pulliam
Hohenwald TN

On Feb 9, 2012, at 10:57 AM, kbreault wrote:

Continuing speculation from other lists re our putative Hoodie given the IN finding.

Kevin Breault
Brentwood, TN

----- Forwarded Message ----
From: "Dinsmore, Stephen J [NREM]" <cootjr@xxxxxxxxxxx>
To: IA-BIRD <ia-bird@xxxxxxxxxxxxxxxxxxx>
Sent: Thu, February 9, 2012 10:36:45 AM
Subject: [ia-bird] Re: Hooded Crane (speculative)

Chris et al.-

I think the main point here is that we advance our knowledge of birds (distribution, patterns of vagrancy, etc.) by taking a conservative stance on unlikely events. In the simplest terms, a hypothesis has been posed that a Hooded Crane arrived in North America naturally, unassisted by humans. Logically, the birding community should strive to amass evidence for, and against, this hypothesis as a means of supporting or refuting it. Support in favor of the hypothesis would have little merit if we didn't pursue it with a healthy amount of doubt! Constructive skepticism is, in my opinion, an essential part of this debate, independent of the ultimate conclusion about its origin. It is also important to recall that the topic of origin in birds spans a continuum of evidence: few of us would consider counting a Lilac-crowned Parrot in Iowa as a wild vagrant from Mexico (a pair frequented Ames many years ago), but almost all of us count as wild any Eurasian Wigeon that appears in the Midwest. Why? Because we have differing levels of evidence for each scenario, which helps us reach conclusions about the most likely origin (wild, or something else).

I am not sure where the Hooded Crane falls, although I am by no means convinced that the evidence unequivocally supports a wild origin. Chris makes a good point about its occurrence with Sandhill Cranes in Nebraska. But it is worth pointing out that the cranes in Nebraska are (mostly) a different subspecies than those in Tennessee and Indiana. If the bird originated in Asia and reached the Great Plains with Lesser Sandhill Cranes, much as we surmise happens with Common Cranes, then why did it make a beeline east and join Greater Sandhill Cranes?

Regardless of the birds ultimate acountability this represents a neat opportunity to view a spectacular looking bird in the Great Plains!

Stephen J. Dinsmore
Department of Natural Resource Ecology & Management Iowa State University
339 Science II
Ames, IA 50011
Phone: 515-294-1348
E-mail: cootjr@xxxxxxxxxxx
Web: http://www.public.iastate.edu/~cootjr/

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