Michael Price wrote:

>Do the southbound jaegers we see come directly from the Pacific Ocean or
>from Georgia Strait or both? If the former, they should enter Juan de Fuca
>Strait from the Pacific and fan out among the various Gulf and San Juan
>Islands, Puget Sound, and Georgia Strait (oddly, at Point Roberts WA, which
>is part of the Greater Vancouver BC Checklist Area, virtually every jaeger,
>north- and southbound, heads past the point from SE to NW; what the heck
>could *that* mean?). Where then? Do they all funnel S into the S end of the
>Sound and then head overland SW to the ocean, as Gene Hunn suggested once?
>Or would some reverse and exit back through Juan de Fuca?

Not only Parasitic Jaegers but a host of migrant "seabirds" (gulls, terns,
and phalaropes at least) come into Puget Sound in the fall, and we all
wonder what their route out of the sound is. I think there have been a few
observations of such birds in the Chehalis River valley, east of Grays
Harbor, but scarcely any compared with the number of birds seen all the way
south to the south end of the sound. Parasitic Jaegers are common off
Point Defiance in Tacoma every fall, along with their Bonaparte's Gull and
Common Tern hosts. Some go all the way down to Nisqually Reach.

There seems no reason for a seabird rapidly migrating up or down the
Pacific coast to use Puget Sound, yet certain species do so in large
numbers. But only certain species do this--many others stay on the outer
coast. The protected waters of BC/WA are obviously very rich feeding
grounds for winter seabirds (most of the winter seabird activity is there
rather than on the outer coast), and those that can efficiently use these
waters in migration apparently do so. Perhaps some of them--Heermann's
Gull being the best example that occurs to me--just retrace their path back
out the Strait of Juan de Fuca, and a lot of bird censuses at Admiralty
Inlet, with records kept of bird flight directions, might answer this.
What are the seasons of abundance at places like Dungeness and Victoria?
Are there bimodal peaks during a wave in and another wave out, or are birds
constantly streaming in and out?

Other birds could migrate at night over the relatively short corridor
between Puget Sound and Grays Harbor, which is why they're essentially
never seen inbetween. But how do birds figure out the route, which they
certainly can't detect visually, for the first time? Do they fly higher
and higher into the air and then set off well above the detection range of
birders? It probably has to be either nocturnal or high-altitude
migration, if they do use that corridor. To me, this is still one of the
big local mysteries. Interestingly, there is much less of a spring
migration through the sound. Is this because of optimal routes or food
resources?

Would that we had the observer power to answer these questions.....

Dennis Paulson, Director phone 206-756-3798
Slater Museum of Natural History fax 206-756-3352
University of Puget Sound e-mail dpaulson at ups.edu
Tacoma, WA 98416