Tweeters,

This afternoon (September 30), I observed 350 Common Mergansers at the head
of Rimrock Lake west of Yakima. I was unaware of a fall concentration such
as this anywhere in Yakima County; not far away at Banks Lake in the Grand
Coulee, however, hundreds or even a 1000 or so can congregate at this
season. Typically, large numbers of mergansers are noted in the Yakima
Valley in late winter when ponds and lakes first thaw.

Nearby were 150 California Gulls, mostly adults, and 10 Ring-billed Gulls
loafing on the mud, created by drawdown of Rimrock Lake.Nearby was an adult
Bald Eagle perched on a stump; in the deeper waters of the lake was a lone
Common Loon and 15 or so Western Grebes.

I suspect the attraction for these birds is the spawning of Kokanee Salmon,
a land-locked, but tiny form of the Sockeye Salmon which is incredibly
abundant in Rimrock Lake. Spawning of this fish is now taking place in Clear
Creek between Clear Lake and Rimrock Lake. The area downstream from the dam
at Clear Lake is probably the easiest place to view this marvelous
spectacle.

Andy Stepniewski
Wapato WA
steppie at nwinfo.net