Hi -
Dave wrote:
"The now annual appearance–followed typically by an almost immediate
disappearance–of Dec–Jan Barn Swallows in the Pacific Northwest remains a
mystery that is not easily explained. "
I think it is important to avoid tunnel vision here. Barn Swallows are
swallows. They are ecologically a bit different from our other swallows,
perhaps, but surely are ecologically more like their fellow swallow species
than like any of the other passerines whose ranges or seasonal distributions
have changed in recent years.
In 1977, when I left Oregon to move to Florida I did not know of ANY record of
ANY swallows in the Pacific Northwest. By the time I moved back to Oregon in
1998 there had been multiple Dec.-Jan records of both Barn and Tree Swallows.
Since then we have had records of most (all?) of our other swallows except
Purple Martins.
I have difficulty buying the idea that the Barn Swallow occurrences are a
special case, with different drivers than the Tree, Violet-green, Cliff,
Rough-winged, and Bank swallow witer occurrences.
I also question the reality of the elipsed (?) assertion, "–followed typically
by an almost immediate disappearance–." I think birder effort has a lot to do
with this impression. Many of the winter swallow records originate on CBCs or
CBC scouting excursions. i personally have seen Barn Swallows in Lincoln
County twice in mid-January in the past 20 years, and I doubt that either of
those sightings is easily extracted from the public record. One was on a
winter raptor survey, so there might be a handwritten note on the bottom of a
data sheet in Jeff Fleischer's file cabinet (and since I was just an assisting
birder and not the person assigned the route, it likely would not be filed
under my name. I likely mentioned the other in a post to OBOL, but likely
without Barn Swallow mentioned in the post.
In addition, as the beginning of February approaches, Barn (and other) Swallow
sightings tend to be thought of as early arrivals, so the possibility of winter
residency tends to be discounted.
Enough ranting.
Wayne
So
On 12/30/2018 12:53:36 AM, David Irons <llsdirons@xxxxxxx> wrote:
The now annual appearance–followed typically by an almost immediate
disappearance–of Dec–Jan Barn Swallows in the Pacific Northwest remains a
mystery that is not easily explained. Arrivals and departures don't appear to
be tied to particular weather patterns. When they disappear are these birds
continuing north to an ultimate demise (presumably) or are they retreating
south? Perhaps they are birds that lingered farther north and are really late
southbound stragglers. It has even been postulated that these birds originate
from Southern Hemisphere breeding populations and that they are long way the
wrong way austral migrants (a la Fork-tailed Flycatcher) that migrate north
when they should be heading south to breeding areas.
Climate change could certainly be a factor, but based on the relatively recent
and sudden onset of this seasonal anomaly, it is hard to buy into a direct
cause-effect relationship. Prior to the early 2000s when the mid-winter Barn
Swallow phenomenon first occurred, Barn Swallows were not showing up at all
regularly in the PNW during winter. They were also not showing up regularly in
Northern California, which might have been precursor to the pattern we've seen
of late. If there was a direct connection to long-term climate change I would
expect that this distributional change would have come on more gradually like
the range expansions of Red-shouldered Hawk, Anna's Hummingbird, Black Phoebe,
California Scrub-Jay and Lesser Goldfinch. All of these species have been
incrementally expanding their ranges northward into Oregon and more recently
Washington dating back to at the 1970's and even earlier in the case of the
Scrub-Jay.
Reverse migrations are well-documented in many species, most notably Tropical
Kingbirds along the West Coast of North America. Tropical Kingbirds (at least a
portion of the population) seems to be 'hard-wired' to migrate north instead of
south following the breeding season. It may be that we are seeing a similar
mechanism expressed in a small portion of the Barn Swallow population. It would
be interesting to capture some of these birds and take some feather and DNA
samples to see which population they are originating from, as that seems likely
to reveal clues that might help unravel this mystery.
Dave Irons
Beaverton, OR
From: obol-bounce@xxxxxxxxxxxxx <obol-bounce@xxxxxxxxxxxxx> on behalf of Lars
Norgren <larspernorgren@xxxxxxxxx>
Sent: Sunday, December 30, 2018 5:13 AM
To: clearwater@xxxxxxxx
Cc: obol
Subject: [obol] Re: Winter Barn Swallow in Central Oregon
There has been strong air movement from south to north the past little while,
which has brought various swallow species to Oregon regularly during CBC season
over the many years. Climate change is always happening. As for anthropogenic
climate change being the reason behind anything and everything...such
unimaginative post hoc propter hoc does a great disservice to science in
general. The Eugene CBC recorded a Turkey Vulture once in the 50s.
On Dec 29, 2018 8:53 PM, <clearwater@xxxxxxxx [mailto:clearwater@xxxxxxxx]>
wrote:
Hi Craig & All,
A few years back we had a Barn Swallow flying around just as volunteers were
coming back in for the countdown at the Thomas Condon Visitor Center in the
John Day Fossil Bed National Monument, for the Antone CBC. Recorded for the
count.
Definitely a good CBC sighting but not unprecedented. Climate change is
happening!
Joel
[obol] Winter Barn Swallow in Central Oregon
* From: Craig Miller <gismiller@xxxxxxxxx>
* To: cobol <cobol@xxxxxxxxxxxxxxxxxxxxx>, OBOL Birders Online
<obol@xxxxxxxxxxxxx>
* Date: Sat, 29 Dec 2018 20:38:40 -0800
Hi all,
While birding at the Crooked River Wetlands, Marilyn and I observed a BARN
SWALLOW flying along the Crooked River. I am not aware of any other swallow
records in Central Oregon during either December or January.
Photos attached
Cheers,
Craig Miller
Bend
