Date: 12/29/18 9:53 pm From: David Irons <llsdirons...> Subject: [obol] Re: Winter Barn Swallow in Central Oregon
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.
From: <obol-bounce...> <obol-bounce...> on behalf of Lars Norgren <larspernorgren...>
Sent: Sunday, December 30, 2018 5:13 AM
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...><mailto:<clearwater...>> 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!
[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
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.