Kings County Falcon re-visited
- Based on new information Steve and I have received, we now believe that the
Kings Co. falcon IS a Gyrfalcon. In fairness to Steve, based on his initial
observations when he found this bird, he has felt all along that Gyr should not
be ruled out.
My main reason for thinking the bird was not pure Gyr was based on size.
That estimate of size was from my 'impression' plus a rough re-sizing of the
Peregrine photo and the Kings Falcon photo which suggested that it was
'slightly' bigger than the Peregrine. Kevin Spencer took the photos and did a much
more meticulous set of measurements. This showed a much larger difference in
size than I recognized. He estimated the Peregrine at 15-16 inches and the other
bird at 20-21 inches (from top of head to tip of tail). Kevin used the
widths of the crossbars on the telephone poles as a 'ruler' to make this
calculation. I contacted a former lineman who looked at the photos and, based on his
experience said that the crossbars look like standard sized one and the widths
are generally in the range of 4-4.5 inches. Steve took these measurements
(using 4.25 inches) and re-measured the two birds. The Peregrine came out at
15.5 inches and the other bird at 20.4 inches. A pdf has been placed in the
Files section of CALBIRDS showing how this was done using the peregrine
photographed five poles down.
Published sources (Wheeler, NGS Guide, Petersen Guide) report the range of
Peregrine length at 14-20 inches and the Gyrfalcon from 19-25 inches. Of
course, these measurements are generally based on specimens measured from beak tip
to tail tip. Therefore, one could add a bit to our top-of-head to tail
measurements made from the photos. In any case, this info puts the Kings County
falcon right into the proper size range for a Gyrfalcon.
Additionally, Steve sent the photos to Brian Wheeler (co-author and
illustrator for the Petersen Field Guide "Hawks" and author of "Raptors of Western
North America") and below is his response:
"This is a dark intermediate morph juvenile Gyrfalcon. Too dark on body and
head for an intermediate or gray morph. I just finished painting four plates
of Gyrfalcons (of 92 color plates) for a set of raptor field guides for
Princeton University Press due out in 2011."
We also got the following comment from Bud Anderson (Washington-state based
director of the Falcon Research Group and a global falcon biologist)
"Nice Gyr. I have no problem with a juv flying to CA. If it is a falconry
bird, it will have jesses. And, to me, its just a standard, perfectly normal
young Gyrfalcon. We see birds exactly like this most every year on the Skagit.
Also too nice and pristine a plumage to have been in captivity."
We have also heard from one falconer with experience with Sakers and various
Gyr hybrids who also believes this bird looks like a perfectly good
Gyrfalcon and also believes this is a wild bird. Comments from other falconers were
all over the map: one said its a Saker, one said Gyr x Peregrine, another Gyr
x ?, another Peregrine x Saker and one suggested Prairie x Peregrine!
Unfortunately, none of this came with details about why any of the characters of
this bird are inconsistent with it being a Gyr. Although I don't know one could
ever completely rule out some kind of Gyr hybrid, in the absence of a single
plumage character that is inconsistent with Gyr, Gyrfalcon should be the
default. If it looks like a Gyr, is the size of a Gyr, flies like a Gyr, maybe it
IS a Gyr.
The only other characteristic of this bird that I didn't like for Gyr was
the relatively 'slim' look. Not bulky and big bodied as nearly all Gyrs look in
photos. Of course, one needs to realize that nearly all those photos are
taken in cold to very cold conditions when a bird is likely to have its feathers
fluffed up. This bird was sitting in Kings County with temps in the
mid-sixties. It also possible that the bird is somewhat emaciated.
Now that we're pretty sure this is a Gyrfalcon, the ugly issue of provenance
comes to the fore. Is it wild or is it an escaped falconers bird? All we can
say is that the bird had no jesses (nothing seen by Steve or myself perched
or in flight), and no bands or anklets could be seen-legs obscured by
feathers. Also, I see no evidence of the kind of feather wear that one often sees in
birds kept in confined spaces. The bird flew away when I approached it, but
then I wasn't holding any raw meat in my hand at the time (got to start
carrying a baggie of raw hamburger from now on).
On the other hand, a wild Gyrfalcon this far south in California is
unprecedented (sort of like a Ross's Gull at the Salton Sea...?). Of the ten accepted
CA records (plus the bird seen this year in Del Norte Co.), the southernmost
records are birds from Yolo/Solano Counties. All other records are from the
'far'' north (Del Norte, Siskiyou, Modoc, Humboldt and Shasta). This puts
this bird over 200 miles south of the nearest prior accepted record. A long way,
but then, not so long for a bird like a Gyrfalcon?
Steve and I are going to gather more input and then put this into the
capable hands of the CBRC (have fun guys--and gal...).
In the meantime this bird could very well still be roaming around the area
and we hope others will keep looking for it.
Thanks to all who contributed comments and to all for your patience in
wading through these LONG messages.
Ed Pandolfino/Steve Summers
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