I'd be interested to hear a forthright account of how long-time CBC
participants have tabulated their miles and counted birds along routes
that require backtracking, whether on foot or by car.
I suspect that there has been quite a bit of variation because:
1. Not everyone has read the rules;
2. The rules have not always been entirely clear;
3. The rules have sometimes been misunderstood; and
4. Not everyone strictly follows the rules.
Thanks to Tim Johnson's posting yesterday, I now realize that I've been
counting my own miles incorrectly now for the past two years. I was
doing it correctly until December 2014 when I read some information
(aimed at eBird users on the NVBIRDS list) that turns out to have been
incorrect in its description of the CBC protocol.
Looking in the CBC compiler's manual:
http://docs.audubon.org/sites/default/files/documents/compilers_manual_oct_2014_0.pdf
and the supplementary guide to miles and hours:
https://www.audubon.org/sites/default/files/guidetocbcpartyhoursmiles.pdf
there is no mention of how to calculate miles for routes with
backtracking.
There is a brief section that discusses how to count birds while
backtracking:
"Counting when retracing census route: If a group needs to retrace their
path along a census route, birds should not be recounted. However, if
additional species are encountered, they should be included in the
census results."
Just to complicate things further, the phrase "birds should not be
recounted" is open to some interpretation.
As a real example from this year's Oakridge CBC, suppose I walk out
along a spur road in the forest and encounter five Chestnut-backed
Chickadees (CBCHs). On my way back I encounter five CBCHs in roughly the
same stretch of road, but also seven in another spot. I also saw a
Northern Pygmy-Owl (NOPO) while going in one direction but not the
other.
Should my total count of CBCHs for that road be 5, 12, or 17?
17 seems wrong, because I suspect that I encountered the same flock of 5
twice, so that could be a case of "recounting."
5 also seems wrong to me. If I'm counting the time that I spend walking
in both directions as part of my "time per unit habitat" (as Mike
Patterson has explained it), that number doesn't reflect the full number
of CBCHs that I found by spending that amount of time on that spur road.
So I'd put down 12 CBCHs as the most sensible number, consistent with
the statistical thinking that goes into the concept of "time per unit
habitat." And I'd count the NOPO even if I saw it on the way back.
But I suspect that others will interpret the instructions differently --
perhaps counting CBCHs only in one direction but counting birds of new
species such as the NOPO on the way back.
Again, it would be interesting to hear how people have actually been
dealing with these kinds of issues during CBCs.
Happy counting,
Joel
--
Joel Geier
Camp Adair area north of Corvallis
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