Hello, Andrea.

Thanks for the news. I wish I could get down there myself to see that, as I've only heard about these WA/OR coastal migrations. It's going on in Oregon as well, although the word used there is "thousands" and not "millions." They are passing at the rate of hundreds per minute at some coastal Oregon sites, but it seems to be very local.

The dragonflies may all be Variegated Meadowhawks (Sympetrum corruptum), our usual coastal migrant. If anyone sees any other species mixed in, I would be very interested. And of course I'm interested in the magnitude of the flight and how long it lasts. What do the dragonflies do when they reach the end of land at Tokeland? Just keep going over the water?

These flights often happen during prolonged easterly winds, the winds apparently concentrating them at the coast, but there is still much we don't understand.

These dragonflies aren't going to Central and South America, merely to California and northern Mexico, but the rest of the story is as you tell it. This is an entirely speculative scenario, but anything we know about them supports it as a reasonable hypothesis. The same thing happens with Common Green Darners (Anax junius) all across the continent, although they may not be common enough to generate such large flights in the West (flights of millions have been seen in the East). There is no comparable spring flight in these species. They just drift northward over a lengthy period, but we know they are migrants, because they appear in spring in the Northwest as fully mature adults ready to breed, with no indication that any are emerging from the water locally.

These fall migrants are coming from all over their range to the north of us, which extends only to southern BC. They are also widespread in the southern parts of the Canadian prairie provinces, but those individuals may migrate east of the Rockies. Observers in the Pasayten wilderness saw very large flights of this species coming across mountains there last week, so this has been a very widespread movement. I speculate that because of global warming, these meadowhawks may be becoming more common to the north of us.

Thanks again, and please keep us informed!

Dennis


On Sep 3, 2010, at 12:02 PM, tweeters-request at mailman2.u.washington.edu wrote:

> Date: Thu, 2 Sep 2010 17:20:53 -0700
> From: "Grad, Andrea E." <agrad at helsell.com>
> Subject: [Tweeters] Tokeland Dragonfly Migration - just started
> To: <Tweeters at u.washington.edu>
> Message-ID:
> <BFCC644419CFED4E9234053F31443301093D586F at helsell2.helsell.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Within the last hour or two, hordes of dragonflies have started passing
> through/over the Tokeland peninsula -- millions upon millions, from the
> looks of it. Last time we observed this phenomenon here, two or three
> years ago, Dennis Paulson enlightened Tweeters with the details of how
> these particular dragonflies are born up here, migrate to Central or
> South America, lay eggs and then die -- leaving their offspring to
> migrate miraculously back, where those then breed and die; their
> offspring head back south with no guidance from previous journeys or
> parents.
>
> Dennis, I would appreciate it if you would please tell us again what
> species they are and correct/refine my recollections above. And do they
> breed/live together up here in relatively close proximity to each other,
> or just gather from far flung places into one large stream when it's
> time to migrate?
>
> Last time we witnessed this, it only lasted two days, with many more the
> first day than the second.
>
> Cheers,
>
> Andrea Grad
> Shoreline/Tokeland
> agrad at helsell.com

-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382
dennispaulson at comcast.net



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