Reading Bill Whan's succinct message on Ohio swans, I have
to say he is right on the money. I would like to go a bit further
and say that after 5 years of reviewing several thousand swan
entries in eBird, that among the most problematic ID issues in
Ohio is that involving swans.
This is no more evident than at Ottawa N.W.R., Magee Marsh W.A.,
and Metzger Marsh in late April and May. Ebird review permits me
to call up all records of both species simultaneously allowing a
side-by-side comparison. In a way, EBird is self-policing in that
at popular birding sites I can see a degree of corroboration or
lack thereof in the multitude of other checklists. This only applies
to the last 5-6 years where there is sufficient sample size.
When I examined every Tundra Swan report for these marshes
from late April through May, none were accompanied by a
Trumpeter Swan record. While not impossible, it is improbable
when compared with the dozens of other checklists in the
same time frame only reporting Trumpeter Swans.
In the most dramatic case, in May 2007 a host of about 25-30
swans were present at Metzger Marsh. One party reported
nothing but Mute Swans, another party nothing but Trumpeter
Swans, and another party nothing but Tundra Swans (on
the same day).
FYI: In the absence of corroborating details, I am forced to
invalidate conflicting entries such as these.
Part of the problem was at my end in that the May checklist
filter erroneously allowed for Tundra Swan sightings without a
call-out from EBird. I changed that a couple of years ago and
there have been no May records since.
While detecting such aberrations at the edge of the distribution
of a species is fairly straightforward, doing so well within their
respective distributions is much more challenging. And this winter
has been especially
so. The introduction of eBird 3.0 in October greatly streamlined
the data entry process making it much more user friendly. In
doing so, now one need not examine one's list at all for errors.
One is encouraged to do so, but only after the fact of submitting
the record. In recent months, I have now contacted about a dozen
persons regarding conspicuous (read flagged) swan entries that
proved to be erroneous typos. But how many have I missed?
I can only ask that if anything is flagged in eBird, that you
PLEASE, PLEASE, PLEASE
check the data entry. And if you have an issue with the item being
flagged by all means comment to that effect. At a minimum, I will know
you intended that data entry. And if I agree with your position, I will
change the threshold, or otherwise provide an explanation for it.
Looking at a snap shot of Trumpeter Swans in Ohio for mid-January 2012
among those that are corroborated and for which I accept as valid, the
state wide tally accounts for about 80-85 birds. The highest valid single
concentration from past years (54) is from a Ottawa N.W.R. census Nov 2008.
the next two highest counts of 50 and 47 are also O.N.W.R. counts
with the latter from 1 January 2012.
I will happily stand corrected should higher verifiable tallies be made
available.
There are several much higher counts without any corroboration from inland
Ohio that seem highly improbable and, without details, I am left no choice
but to leave invalidated.
Finally, a clarification regarding Trumpeter Swan movements. It is generally
true they disperse little and not far however there are some exceptions.
Namely, there are several Pennsylvania and Virginia
records, of which some are birds from Ohio. One of the Virginia records
is published in North American Birds. The other is very recent. See ...
http://www.flickr.com/photos/22374475@N07/6847490621/in/pool-437129@N20/
or this eBird entry
http://ebird.org/ebird/view/checklist?subID=S9778289
Birds of the Upper Midwest (Minnesota/Iowa) do seem to be developing
greater dispersal capabilities and routinely reach Oklahoma and may well
be responsible for recent Texas sightings. Do any of these birds augment
winter populations in Ohio? I have no idea.
This plot of winter distributions of the Trumpeter Swan for the past 10 years
may be informative.
http://ebird.org/ebird/map/truswa?neg=true&env.minX=-104.62501571425179&env.minY=28.6734397372551&env.maxX=-62.43751571425179&env.maxY=43.820425522158736&zh=true&gp=true&mr=12-2&bmo=12&emo=2&yr=2002-2012&byr=2002&eyr=2012
OR
http://preview.tinyurl.com/6mpvajb
Keep in mind that "Swan sp." or "Trumpeter/Tundra Swan" are perfectly
legitimate data entries in eBird.
.
NOTE:
.......ANY correspondence should address me at [log in to unmask]
and I welcome any inquiries regarding eBird.
cheers
Vic Fazio
Shaker Hts, OH
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