Thanks for the response and the numbers George. One thing I was finding
curious was that although diving duck populations in general are
extremely low, COMMON MERGANSER numbers seem to be fairly consistent
with past years. Maybe it's not so curious given your hypothesis that
the decrease in diving ducks is due to destruction of lake bottom fauna.
Of the divers I would expect they would be least impacted by bottom
fauna changes therefore resulting in more stable numbers.
>>> <chaniot@...> 02/10/04 04:50PM >>>
>So far this year I've been up to Lake Mendocino three times and have
>to see a single LESSER SCAUP. GREATER SCAUP are easy to find though
>numbers seem to be significantly lower than normal (actually the
>of ducks in general seems to be very low). It's been my experience that
>the split between LESC and GRSC on the lake is fairly even. Has anyone
>seen a LESC on the lake this year and if so from where? How many were
>seen on the CBC and what was the ratio between scaup species? Any
>theories on where they are?
Matthew is on to something here. Lesser Scaup are very hard to find
at Lake Mendocino. In past years the numbers of scaup overwintering on
Mendocino has been in the 1000-4000 range. This year the number is in
150-300 range, and Lesser Scaup is almost absent. Unbeknownst to anyone
myself, I have begun doing a weekly survey of the waterfowl on Lake
Mendocino, weather permitting, starting in Sep 2003. I had become
with the low numbers of ducks in the 2002/03 winter and decided to start
documenting numbers. I have found a few Lesser Scaup, but it is
In the last two weeks the ratio of GRSC:LESC has been 124:3. The scaups
have been mainly in the north end in the Pomo A area and up in the inlet
almost to the Hwy 20 bridge.
As for the low numbers of diving ducks, I am sticking to my
hypothesis that it is due to the draw-down of Lake Mendocino in the fall
2002 causing destruction of the bottom fauna, principally the
fingernail-sized clams which the diving ducks and some dabbling ducks
be seen to be eating. If this is true, I predict the numbers will begin
increase in the coming years as the bottom fauna recovers. In the fall
2002 scaup arrived in usual numbers, but they did not remain even when
water level came back up (Remember that Christmas Count?!). In the fall
2003, the numbers never built up.
In addition there has been a long-term decline in numbers of both
scaup since the 1960's becoming serious in the late 1990's. See
for a 1998
discussion. I have heard that Ducks Unlimited has recently declared
Scaup a species of concern, but I don't know anything particular about
The Ukiah Christmas count numbers up to 2002 can be found at the
Peregrine Chapter Website.
I am also concerned about the future of wintering waterfowl at Lake
Mendocino if the lake level is raised by 40 feet.
Potter Valley, MEN, CA
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