[obol] White-throated Sparrows wintering population in OR increasing?

[David Bailey]

Fellow intellectuals:

I want to thank both David Irons and Mike Patterson and others for 
keeping this discussion going as to whether the observed increase in 
WHITE-THROATED SPARROWS wintering in Oregon is due to a population 
increase or to is an artifact of increased observers, and observer bias 
(better educated birders working the right habitat to find rare sparrows).

Mike does an good job of presenting the available evidence from the 
Audubon Christmas Bird Count (CBC) data for counts going back to their 
beginnings in Oregon. He shows convincingly that if we accept that 
White-throated Sparrows have increased, we must also accept that 
Lincoln's Sparrow and Swamp Sparrow winter populations in the state have 
also increased. I did some additional research using the CBC database 
inspecting the data for Golden-crowned, White-crowned, Fox, and 
Clay-colored Sparrow. All show an increase as well. Song Sparrow remains 
flat, probably because they are so conspicuous in their habits (quickly 
respond to intrusion and their often uttered "chimp" call) and well 
known to most birders.

If you haven't looked at Mike's we blog on this topic, you may find it 
informative:

http://www.surfbirds.com/blogs/mbalame/archives/2007/04/is_it_a_population_trend_or_is.html

and the Audubon CBC database with interactive user-based querying:

http://www.audubon.org/bird/cbc/hr/

The lid is certainly not sealed on this question, but the evidence 
presented so far supports the observer bias hypothesis more than the 
population increase hypothesis.

To know is not enough.

"If we knew what we were doing, it wouldn't be called Research." A. Einstein

Sincerely,
David C. Bailey