[obol] Re: Early Swainson's Thrush reports
- From: Timothy Kadlecek <timkadlecek@xxxxxxxxxx>
- To: contopus@xxxxxxxxx
- Date: Sun, 27 Apr 2014 17:21:58 -0700
I have one comment to add regarding a recent experience with the Swainson's
Thrush song. I birded in Colombia, SA for 9 days this past March. We had
seen a couple Swainson's Thrushes as well as heard its "whit" call a couple
times on the morning of March 16th at Chicaque Park, about 1.5 hours drive SW
of Bogota. We also heard one sing its classic spiraling song that morning.
In fact our guide who knew just about every bird by sound said she did not
recognize this one and I had to let her know what it was and played it for her
on my iPhone. She said she does not recall ever hearing one sing in Colombia
before.
Tim Kadlecek
Portland
On Apr 27, 2014, at 9:13 AM, Wayne Weber <contopus@xxxxxxxxx> wrote:
> Dave,
>
> Thanks for your long and detailed discourse on early spring reports of
> Swainson’s Thrush-- delivered in your usual eloquent fashion. What you said
> needed to be said. From my perspective in and around Vancouver, BC, I deal
> with much the same problem. Every year, as the Vancouver regional editor for
> eBird, I deal with numerous April reports of Swainson’s Thrush, nearly all of
> which are questionable. Most of these are probably misidentified Hermit
> Thrushes. I get some April reports of SINGING Swainson’s Thrushes, and I can
> be quite certain that these are erroneous. Despite the fact that this is one
> of the most distinctive of all bird songs, at least to me, some birders seem
> to mistake other species for Swainson’s Thrush. In my experience, and that of
> nearly all other birders, Swainson’s Thrushes (and other brown thrushes) DO
> NOT sing on migration, and in fact not until about 10 days to 2 weeks after
> they arrive on territory-- starting about May 20th or so. For the most
> part, the first Swainson’s Thrushes that are reported give a series of soft
> “whit” calls, or hop out briefly onto a forest trail in silence. Most of them
> are probably overlooked because of their silence.
>
> Nevertheless, we do get a few credible late April (but never early April)
> reports of Swainson’s Thrush in some years. I, like you, am one of those
> birders who pays great attention to migration arrival and departure dates,
> and I have religiously compiled tables of such dates for Vancouver since the
> late 1960s. For Swainson’s Thrush, our mean arrival date over 32 years is May
> 6th in Greater Vancouver. However, for 9 years, the arrival date was in
> April: arrival dates vary from April 16thto May 20th. Some of the April
> arrival date records are by long-experienced and reliable observers that I
> have no reason to question. Nonetheless, April arrival dates in Vancouver are
> unusual for Swainson’s Thrush, involving only a tiny vanguard of the
> population (Joel Geier makes a good point), and I will continue to question
> nearly all April records of the species.
>
> Despite all this-- two days ago, on April 25th, I was birding along Shaw
> Road, a forested road just south of Lake Samish in Skagit County, in
> northwestern Washington. There were quite a few spring migrants about,
> including 2 Hermit Thrushes. One of the birds I recorded was a Swainson’s
> Thrush, which gave a series of about 15 “whit” calls in the forest uphill
> from Shaw Road. No, I did not see the bird-- searching through the dense
> forest undergrowth would have been a futile effort-- but this is a call I
> learned to identify more than 50 years ago, and I am as certain of this
> identification as of any of the other birds I saw and heard that day.
>
> Dave, you may have failed to find Swainson’s Thrushes in April for 40 years
> or more, but I predict that you will see or hear one, one of these years;
> April Swainson’s do occur occasionally, even in BC. It’s easy to say “if I
> haven’t seem ‘em in April, they don’t occur in April”, but “rarely” is not
> the same as “never”. To you and to anyone else who has to review
> exceptionally early reports of Swainson’s Thrush, my advice is: be critical,
> question these reports and request photos or other evidence, but be willing
> to admit that a few of these reports are valid. And birders, if you do report
> Swainson’s in April, be prepared to be questioned and to provide some details
> of your sighting!!
>
> Wayne C. Weber
> Delta, BC
> contopus@xxxxxxxxx
>
>
>
> From: obol-bounce@xxxxxxxxxxxxx [mailto:obol-bounce@xxxxxxxxxxxxx] On Behalf
> Of David Irons
> Sent: April-25-14 12:34 AM
> To: Brandon Green; OBOL Oregon Birders Online
> Subject: [obol] Re: Spring Arrival Dates: Long and likely annoying for some
>
> Brandon,
>
> For more than a week now (since at least the 16th of April) there have been
> almost daily reports of Swainson's Thrushes showing up on OBOL and in the
> daily eBird rare bird alert for Oregon. I believe that every single one of
> these reports is suspect. I looked at the eBird map that you provided for
> all-time April reports of Swainson's Thrushes. It covers many years and has
> several clusters of reports that are highly questionable. That said, there
> are some from observers who none of us have any reason to doubt. These
> reports, seem to be clustered (for the most part) over the last few days of
> April (27th-30th). I consider any report in April to be early and any report
> before about the 25th of April to be exceptionally so. We can argue over how
> to define "exceptional," but that's really not the point.
>
> We go through this exercise every Spring on OBOL. The fact of the matter is
> this, not that many birders pay close attention to spring arrival dates and
> if asked many could not tell you when Swainson's Thrushes, Yellow Warblers,
> Warbling Vireos, or Willow Flycatchers normally arrive in the Willamette
> Valley. Without an understanding of spring migration phenology, one is
> unlikely to apply much rigor or objectivity to what they think they are
> seeing because they have no reason to. If you believe what you are seeing is
> normal, why would you question it? If on the 20th of April you see a bird
> that looks like a Swainson's Thrush (the default w. OR thrush in the minds of
> many Oregon birders) and you don't think or know that a 20 April Swainson's
> Thrush is unusual, would you be skeptical about your own observation?
>
> If you look around the OBOL 'room,' the folks who view these early Swainson's
> Thrush reports with skepticism are folks like Jeff Gilligan–Jeff has been
> birding in Oregon for 50+ years; Tim Rodenkirk–Tim goes birding almost every
> day, keeps a very detailed database on the comings and goings of birds in
> Coos and Curry counties. Tim can authoritatively answer almost any question
> about the abundance, distribution, and seasonality of birds in these
> counties, I know because I regularly ask him such questions; Wayne
> Hoffman–Wayne has been birding in Oregon for decades and has been a very
> active birder since at least the 1970's); Mike Patterson–Mike has been
> birding in Oregon since the early 1970's (at least). He has been the Oregon
> CBC editor for North American Birdsfor about two decades and he has been
> banding along the Oregon coast (Swainson's Thrush central) for 11 years.
> These are birders who have been to this rodeo. We've all encountered out of
> season reports of Swainson's Thrushes made by folks who were absolutely
> certain of what they saw. Swainson's Thrush gets reported on an Oregon CBC
> every year. Hermit Thrush is the only Catharus thrush that regularly winters
> in Oregon, whereas Swainson's is a mega-rare bird here in winter. Swainson's
> also get reported somewhat regularly in late March and the first 2-3 weeks of
> April, when Hermit Thrushes are the default thrush in western Oregon.
>
> Ever since I started birding seriously, I have paid particularly close
> attention to migration/arrival/departure dates. Back in the mid-1980's David
> Fix, Steve Heinl, and I shared an apartment at the base of Skinner's Butte in
> Eugene (3rd and Pearl). During spring migration, we birded the Butte every
> single day, often making more than one trip up the hill per day. At the
> beginning of every season, we would make our predictions for the exact day
> each neotropical species would first appear on the Butte. We were rarely off
> by more than a couple of days. As the years passed and our sphere of "young
> guard" birding buddies grew to include Matt Hunter, Dennis Rogers, Rob
> Fergus, David Bailey and Jim Johnson, this game only intensified. We all
> started each spring migration on a mission to find as many "first of the
> season" birds as we could. If there were mid-April Swainson's Thrushes to be
> found, I dare say one of us would have found them. I'm pretty certain that
> I've never seen a Swainson's Thrush earlier than 3 May (and I was surprised
> by that one). Since those early days, I've done a couple of stints writing
> field notes for Oregon Birds and I've been Oregon's Regional Editor for North
> American Birds since 2003. In order to write these columns, one has to be
> intimately familiar with migration phenologies.
>
> There are two additional phenomena that are somewhat universal in the birding
> world. One might be described as "me tooism." The other is the tendency to
> embrace oversimplified one-size-fits-all explanations when it comes to
> explaining early or late reports.
>
> Me Tooism -- Once a bird is reported by a seemingly trustworthy observer, it
> is as though a permission slip has been issued to the rest of the birding
> community. If an early report of say a Swainson's Thrush or Willow Flycatcher
> is posted on OBOL, you can almost predict a number of "me too" reports in
> subsequent days. "If birder X is reporting one, they must be around."
>
> Oversimplified Explanations -- This season's example is the combination of
> drought in California and the stretch of unseasonal warm and sunny weather
> that we enjoyed during the first two weeks of April. At some point there was
> some chatter on OBOL about birds arriving early in California and that the
> drought and nice early April could explain some surprisingly early reports in
> Oregon. Again, another permission slip was issued. A smattering of early
> arrivals occur every spring migration. What we've seen this year can hardly
> be considered an anomaly. Also, the generally poor understanding of phenology
> among rank and file birders leads to birds being reported as "early" or
> "late" even when they aren't. There were questions about the first Hammond's
> and Dusky Flycatchers on Skinner Butte. These two species show up every year
> by the 15th of April, often a few days earlier. This spring there have been a
> few species that have shown up 2-5 days earlier than the normal FOS reports.
> However, aside from the flurry of Swainson's Thrush reports and the likely
> incorrect report of a Willow Flycatcher from Detroit Lake, I can't think of
> any reports that I found to be shockingly early.
>
> The California drought and warm spell probably shouldn't be offered as a the
> reason for multiple Swainson's Thrushes being reported between the 15th and
> 20th of April (at least two and more like three weeks early). If you look
> into the points of origination, the migration routes, and the timing of
> spring migration for the many neotropical species that pass through Oregon in
> the Spring, you'll realize that a single factor like the California drought,
> or the period of nice weather we had in April is unlikely to have had a
> wholesale effect on the entire suite of neotropical migrants. Some birds
> start in the desert southwest, some start in Mexico and Central America, and
> others come from as far away as South America. The routes taken to reach
> Oregon do not follow a single pipeline running straight up through
> California.
>
> Approximately three full months pass from the date when the first Rufous
> Hummingbird (the earliest neotropical migrant) reaches the southern Oregon
> Coast, to the date when the first Common Nighthawk (the latest neotropical
> migrant) arrives in the Siskiyou Mtns. and the southern reaches of Oregon's
> Coast Range. When they left their wintering grounds, these birds could not
> have known that they would encounter drought conditions in central
> California, or that a 10-14 day stretch of really nice weather would occur in
> Oregon during early April. In reality, these comparatively local
> climate/weather anomalies probably didn't alter the path or the timing of the
> migrations for most species. Perhaps the early wave of Western Kingbirds that
> we had might be attributed to birds finding no food in California's
> drought-stricken Central Valley and continuing to push north, but it's hard
> to know. Most of the other species that typically show up in the first half
> of April (Hammond's Flycatcher, Pacific-slope Flycatcher, Cassin's Vireo,
> Nashville Warbler and Black-throated Gray Warbler) appeared on schedule. In
> recent days, there have been ever so slightly early Black-headed Grosbeaks
> and a Yellow Warbler, but true outliers have been no more numerous than a
> 'normal' spring based on the reports that I've seen.
>
> I'm sure that I appear more skeptical than most about out of season reports.
> This skepticism doesn't come from being a cranky, distrustful old guy who has
> nothing better to do with his time than cast doubt on the reports of other
> birders. My skepticism comes from 40+ years of seeing the same ID mistakes
> repeated year after year. I endorse the use of eBird and I think it is a
> wonderful tool. I have a similar opinion of OBOL, as it among the most lively
> and educational statewide birding forums in North America. Despite these
> endorsements, I do not accept (at face value) everything that I see reported
> through via these forums.
>
> If you think you are seeing a Swainson's Thrush in Oregon during April, I
> encourage you to take and post photos. It may seem silly to document a
> species that will be dirt common throughout much of Oregon a month from now,
> but if we are to stretch the bounds of current knowledge, rigor, objectivity,
> and proof need to be part of the process.
>
> Dave Irons
> Portland, OR
>
Other related posts:
