[obol] Re: terns
- From: Alan Contreras <acontrer56@xxxxxxxxx>
- To: David Irons <llsdirons@xxxxxxx>
- Date: Mon, 22 Dec 2014 07:05:23 -0800
There was also Lee Cain's Common Tern yesterday, a bird that can be confused
with Aleutian. I don't have any doubts about the Caspian or Forster's reports.
There is a Forster's record for December in Bandon.
Reports that I saw indicated that the air mass from the latest flow originated
in the south China Sea, not Hawaii. Maybe they were wrong, but that's what the
news carried.
Alan Contreras
Eugene, Oregon
acontrer56@xxxxxxxxx
Sent from my iPhone
> On Dec 21, 2014, at 10:41 PM, David Irons <llsdirons@xxxxxxx> wrote:
>
> Greetings All,
>
> There are a couple of significant problems with Alan Contreras's speculation
> below (in italics). The moisture source for the atmospheric river events
> colloquially referred to as a "Pineapple Express" are the moisture-laden air
> masses that surround the Hawaiian Islands, which are more than 5000 miles to
> the east and north of the The Phillipines. Further, we aren't dealing with a
> number of terns. There have been just two that I've seen reported in recent
> days.
>
> I'm going to play devil's advocate here and suggest that winter terns showing
> up on the tail of storms that originate in the southwest Pacific may not be
> standard-model Oregon species at all. For example, Aleutian Tern winters
> around the Philippines and its winter range is otherwise poorly known. Just
> sayin'.
>
> The smaller tern reported on the Tillamook Bay CBC was described as a
> Forster's, which, not surprisingly, is the small tern species that winters
> closest to Oregon–regularly to San Francisco Bay about 650 miles from
> Tillamook and occasionally as far north as Humboldt Bay–about 380 miles from
> Tillamook. Forster's and Aleutian Terns are quite different in terms of face
> pattern and wing pattern, the features generally most reliable for separating
> the smaller white terns. I don't know who saw this bird and identified it as
> a Forster's, but those persons apparently offered a convincing description of
> a Forster's to Owen Schmidt, the Tillamook Bay CBC compiler. Unless there is
> compelling evidence to suggest otherwise, it is probably reasonable to accept
> their identification. The reported species would have to be considered the
> most likely small tern to occur in Oregon during the winter months.
>
> A few days earlier (before the latest system arrived) Mike Patterson
> described a large tern that he felt was a Caspian–a species that he sees
> almost daily for 5-6 months of the year. Mirroring Forster's, Caspian is the
> most northerly wintering species among the larger terns. They too now winter
> somewhat regularly around San Francisco Bay and occasionally north to
> Humboldt County.
>
> A check of the eBird database reveals numerous recent (last 4-5 years)
> Dec-Feb reports of both Forster's and Caspian Terns from sites around
> Humboldt Bay. While it is fun to speculate about the influences of weather on
> birds, it is important to make sure that we are being realistic when we start
> connecting coincidental dots. There is no indication that the Pineapple
> Expresses are originating from The Phillipines, or that Aleutian Terns winter
> in the waters where the atmospheric rivers spawn. Seems to me that it is far
> more likely that the birds we are seeing are coming from a few hundred miles
> away rather than many thousands.
>
> Dave Irons
> Portland, OR
>
>
>
>
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