Hello, Birders.
Thanks to Dave Silverman for raising two important points.
> As a member of the CO Records Committee, I would simply ask birders
> if they feel it"s best for the Committee to err on the side of caution, when
> reviewing mega-rarities and vagrants such as the Rufous-collared Sparrow?
> I would also add that the categorical dogmatism expressed in some of the
> emails regarding the Sparrow is in poor taste and detracts from the quality
> of cobirds.
I strongly agree with Dave on his second point. Categorical dogmatism--here on
COBirds or in any other venue--is vulgar and uncouth. I can think of only two
more grievous offenses: (1) failure to indicate the date and county for each
and every report submitted to COBirds; and (2) use on COBirds of four-letter
"banding" codes, which are an abomination and an offense against humanity.
As to Dave's first point, no, I don't really agree--at least not in any
blanket, categorical sort of way. "Standard operating procedure" for science in
the 21st century is to state a "null hypothesis" (basically, a reasonable
starting point) and then to attempt to disprove it--that is, to provide a
defensible case for some "alternative hypothesis." It is very important to
start off with a good null hypothesis. A huge number of scientific careers (not
to mention bird records committee deliberations) have been wasted by wild goose
chases that started off with the wrong null hypothesis!
In the case of the Georgetown (Clear Creek County) Rufous-collared Sparrow, I
have already said--and I'll say it again in the paragraphs to follow--that I
believe the correct null hypothesis is that the bird is wild. That is the most
fundamental--the most "conservative," if you will--null hypothesis for a bird
of uncertain origin observed in the wild. Sometimes that null hypothesis is
wrong; sometimes it is right. But it's a good starting point.
Moving right along, I just heard from Paul Handford, probably the world's
foremost authority on the ecology of the Rufous-collared Sparrow. He's
interested in our bird, to say the least. He started out by saying that it's
interesting that the Georgetown bird is singing at the "correct" time of the
year, adjusted for daylight conditions in the northern hemisphere. Usually, the
species sings only sping-summer.
Now it gets a lot more interesting. Despite several assertions--why, they came
across as categorical dogmaticism!--here on COBirds, this species is not at all
sedentary. The more southerly populations are all long-distance migrants,
dispersing several *thousand* kilometers on their spring and fall migrations. I
note that the bird's first detection in Colorado is perfect timing for an
austral-migrant overshoot on its "fall" migration northward from Patagonia. In
this regard, think about the recent record from the USA of a White-crested
Elaenia. That bird was shown not to be from one of the equatorial (and mainly
sedentary) populations, but rather from a migratory population occurring much
farther south.
But don't get too excited. Handford has looked at the photos of this bird, and
he says it is without question *not* one of the strongly migratory subspecies.
So we're back to a sedentary tropical population? Hold your horses. There's a
fair bit of annual altitudinal movement--again, contrary to some of that
categorical dogmatism expressed here on COBirds--among the higher-elevation
breeders even in the tropics.
Bottom line: Rufous-collared Sparrows move around. A lot. And as Bob Righter
importantly reminded us, birds' capacity for long-distance dispersal is a lot
more impressive than many of us realize. Here are a few examples: How many
folks realize that ptarmigans, those exemplars of sedentariness, *routinely*
migrate hundreds of kilometers, with occasional forays by Willow Ptarmigans
down into the Lower 48? And did you know that *flocks* of Rock Ptarmigans
sometimes migrate out over the Bering Sea? How many folks realize that European
Starlings are strongly migratory? How about the Golden-cheeked Warbler, a
short-distance migrant, that made its way to northern California? How about
supposedly non-migratory Long-billed Thrashers that have shown up on several
occasions in Colorado? I could go and on.
I still suspect that this bird is an escape. But I don't feel too strongly
about it. I'm not anywhere near 99.99% certain. Not 99%, either. Heck, not even
90%. Well maybe. Call it 91%. (Steve Mlodinow, is your bro's head exploding
right about how?)
My basic point ought to be pretty obvious by now. I don't see how we can begin
to assert--with any amount of categorical dogmatism--that this bird is an
escape. I believe the Colorado Bird Records Committee should evaluate this bird
from the standpoint that is a naturally occurring ("wild") vagrant. If that can
be disproved, great. If not, then the null hypothesis (i.e., the bird is wild)
remains unrefuted, and therefore--according to the view of the majority of
folks operating within the modern scientific framework--valid. CBRC, have at
it! Disprove the null hypothesis that this bird is wild. Otherwise, we're
counting it!
I already have.
Ted Floyd
[email protected]
Lafayette, Boulder County, Colorado
--
You received this message because you are subscribed to the Google Groups
"Colorado Birds" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/cobirds?hl=en.
