The exchange on CBC methods has been interesting and potentially productive
in terms of promoting more consistent methods in the future. For my part, I
have been participating in and helping to organize CBCs for more than 50
years (in at least 7 states from Alaska to Pennsylvania), and I have
always followed the protocol described at the link Joel provided for the
2013 CBC guidelines:
"A route re-traced on foot should only include the one-way distance. For
example: If a field party walks out a path through a woodland to a distance
of 1 1/2 miles and returns the same way, the distance is reported as 1 1/2
miles , not 3. The entire time spent on the path should be reported, not
just that of the one-way distance."
I follow this same protocol whether on foot or in my car, and the reason is
very straightforward: When you cover the same area twice, you are searching
one area more intensively, but it is still the same area. The time you
spend searching reflects the intensity of effort, while the one-way
distance traveled reflects the area covered.
If a hotspot is visited multiple times in one day, as Alan mentions, the
maximum count recorded at any one time for a given species is the
appropriate number to use. This is analogous to a feeder count.
Researchers analyzing CBC data generally use party hours as the measure of
effort rather than distance traveled, though the specific metric chosen
depends on the purpose of the analysis, species being studied, etc.
Stan Senner
Portland
Msg: #8 in digest
Subject: [obol] Re: Of birds, time, distance, and humans
From: Joel Geier <joel.geier@xxxxxxxx>
Date: Fri, 06 Jan 2017 10:58:20 -0800
P.S. It turns out that the CBC guidelines for how to calculate miles on
routes that involve backtracking were stated in the 2013 version of this
document:
http://docs.audubon.org/sites/default/files/documents/
guidetocbcpartymileshours_0.pdf
but that paragraph was omitted in the more current (2014) version:
https://www.audubon.org/sites/default/files/guidetocbcpartyhoursmiles.pdf
I'll mention this to the national CBC staff at a more suitable time,
after they're past the busy season.
--
Joel Geier
Camp Adair area north of Corvallis
