Rob Raker
Lakewood, CO
On Saturday, February 13, 2021 at 9:22:00 AM UTC-7 Bryan Guarente wrote:
COBirders,It has been an interesting three weeks in the eastern provinces of Canada. Newfoundland, New Brunswick, and Nova Scotia have had an influx of Redwings (Turdus iliacus; the European species, not the blackbirds we know and love). There have been 6 different instances of Redwings spread across those three under-birded provinces (eBird map of Redwings in North America). Ornithologically, this is significant. Meteorologically, this is also significant. The Polar Vortex has been mentioned in many circles recently in relation to the cold we are feeling Friday through the weekend. There was a strong wobble in the polar vortex recently that led to a strongly different pattern of winds over the North Atlantic Ocean. This has caused a long period where there have been relatively consistent easterly winds from England/Iceland to the northeast reaches of North America. This is backwards from the normal pattern of westerly (from west to east) winds we expect to see in the Mid-latitudes.In all of the following web links, make sure you remember that this is on a globe, so you will need to orient yourself appropriately to the latitude/longitude lines to understand the winds.Here's an example of the backwards pattern:Sighting #1 showed up in New Brunswick for a two hour period then disappeared (1/21).Sighting #2: showed up in Newfoundland on 1/25 in St John's:Sighting #3: showed up in Newfoundland on 1/29 in Stephensville:https://earth.nullschool.net/#2021/01/28/2100Z/wind/isobaric/850hPa/orthographic=-30.97,52.95,835 This one makes meteorological sense, but it isn't a strong case. I am guessing this one was already local and showed up to where someone reported it.Sighting #4: showed up in Maine on 2/1:https://earth.nullschool.net/#2021/01/31/2100Z/wind/isobaric/850hPa/orthographic=-30.97,52.95,835. This one is another case of possible dispersion to somewhere that it was reported at a later date than when it probably showed up. But we are still in the same type of weather pattern with winds out of Iceland/England which would dictate some movements like this if a bird leaves those island nations.Sighting #5: showed up in Wolfville, Nova Scotia on 2/3:https://earth.nullschool.net/#2021/02/02/1900Z/wind/isobaric/850hPa/orthographic=-30.97,52.95,835. This is a more typical winter pattern for the North Atlantic and NE North America. This seems to be a wandering of one of the birds already in North America in my mind. The wind pattern was NOT conducive for more Redwings to be coming to this side of the pond.Sighting #6 and #7: showed up on the same day (2/12) in Crystal Crescent Beach, Nova Scotia and in Crow Neck Beach, Nova Scotia:And as a weird side note, there has also been a Redwing that showed up in Victoria, British Columbia yesterday (2/12) as well. There are two subspecies of Redwing (T.i.iliacus and T.i.coburni). If these birds are identified to subspecies, it would be interesting to see if the British Columbia bird is of the coburni subspecies as that one breeds in Iceland and winters in far western Europe as opposed to the mainland Eurasia subspecies T. i. iliacus. Either subspecies is possible in the US/Canada, but the coburni subspecies would be exceptional in British Columbia and would lead one to believe that this bird likely crossed the entirety of the Atlantic, THEN all of Canada to reach the B.C. coast. It isn't that likely from the wind pattern, but possible. It is much more likely that the B.C. bird is of the other subspecies and likely came from Asia rather than Europe.Hopefully this was fun arm-chair birding while it is cold out. If there are any questions about this, please ask. This is a fun time to explore old records and dig in on winter vagrants.Good birding to you,BryanBryan GuarenteMeteorologist/Instructional DesignerUCAR/The COMET ProgramBoulder, CO
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