Date: 10/28/20 11:30 am
From: larspernorgren <larspernorgren...>
Subject: [obol] Re: Catharus thrush phenology
Last Monday, October 19, a Swainson's Thrush was captured at the OSU birdbanding program at Luckiamute Landing.  This followed a week of late detections on eBird, almost all based on audial criteria, by highly seasoned observers. Equally significant--the lead bander in the program who has had hundreds, maybe thousands, of live SWTH in the hand proceeded to report the vital statistics of another SWTH and when I, the recorder, had filled in 75% of the blanks she declared,"No,wait! This is a Hermit Thrush." I had the identical experience last year in early September, when the bander was different, and easily in the 95th percentile at field ID of Oregon birds. In his case he had only given me 50% of the data that fills in the standard blanks when he switched ID. The banders' secret weapon is the 6th(or 4th?Pyle is 50km behind me in the circadian rhythm) primary, which has a very distinct shape between HETH and SWTH. If you can mistake them in the hand, don't trust the color criteria in the field. The subspecies group of Swainson's we deal with is the RUSSET-BACKED Thrush. They often have warm brown on the dorsal surface. It is often stronger on the rump and/or tail. It's an ancestral trait. Remember the Nightingale.       Multiple subspecies of Hermit Thrush in the American west have little or no rusty on the rump, including some nesting in sw Oregon and western California. Swainson's Thrushes nesting in interior western Alaska have white cheeks and are part of the Russet-backed group. Multiple subspecies of Hermit Thrush have warm buffy cheeks and/or upper chest. I noticed this on various CBCs before l did any indoor research. As for breast spots? I don't know , but I doubt they are definitive.  Most SWTH on our continent, from Alaska to Newfoundland, are in the Olive-backed group. This includes Oregon's own Blue Mountains. When l saw a single example in the hand in August of 2019 it really stood out for its cool tones to the back  feathers.     Captures of Hermit Thrush were high at Luckiamute Landing 10/19-21, and audial detections very high that Monday. Red-necked Grebes, Red-breasted Mergansers, Scoters, are appearing all over Oregon at the moment. The north woods are emptying and HETH is part of that package. I'd say there's a 95% chance your bird was a Hermit Thrush, Paul. The Swainson's banded Monday 10 days ago was a hatchyear bird with no fat, a mildly injured wing, and a deformed back toe ,perhaps the result of virus. A classic straggler.Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Paul Sullivan <paultsullivan...> Date: 10/28/20 9:44 AM (GMT-08:00) To: <obol...>, YamhillBirds <yamhillbirds...> Subject: [obol] Catharus thrush phenology It’s foggy here in McMinnville this morning.  Just moments ago at 9 AM, I was scanning my backyard, counting the increasing number of juncos (up to 12 now), when a brown bird emerged from under a bush.  I thought, “Oh good, a fox sparrow.” Then I realized, “No, it’s a THRUSH!”  I locked on it with my binoculars as it hopped straight toward me, showing the thrush, not sparrow beak.  Was it hermit or Swainson’s?  My first thought was Swainson’s, but then I thought could it be hermit?  I was waiting for it to turn and show me its tail, when it suddenly exploded sideways out of my field of view and was gone.  I haven’t seen it again. I checked my copy of The Birds of Rummel Street that tallies 23 years of sightings in this backyard (1993-2016).   The data displays presence or absence of a given species in each of 4 weeks in each month of each year.Swainson’s thrushes were recorded in 58 times, all between the first week of April and the first week of October.Hermit thrushes were recorded in 3 times between May and October, and 4 times between the third week of November and the second week of February. What do folks who follow phenology say? Paul SullivanMcMinnville
 
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