It has been of interest following the discussion on RBME (red-breasted
Merganser) numbers in recent days.  John posed an interesting and maybe
alarming question that answers aren't easy to come by.  As can probably be
said in any wildlife question there are many threads of effect and teasing
them apart is difficult and often speculative which can be a dangerous place
to go. Having supervised 30 years of waterfowl monitoring programs for the
state and having a life long interest let me throw out some comments.

First we simply don't know the answer.

RBME are not well represented in breeding surveys that have been ongoing
since the 1950s because the vast majority of the population nest north of
the prairies and parklands where flying is risky at best, so USFWS does not
make estimates from questionable data.  However, the new eastern survey
which does count mergs (although as has been mentioned can not differentiate
reliably from the air, species) shows no change in the past decade of
breeders. So is breeding not a problem or are there contaminant problems
similar to those indicated with scaup that are going undocumented because of
breeding range.

Staging numbers, which have been mentioned in discussion has been of
question.  No where else before or after are RBME seen like they are on Lake
Erie.  There aren't any "new" sites being reported to the north. Could they
be changing location within the Lake, maybe.  The ecosystem with all the
invasives is changing. ODOW surveys are designed for lake shore and marshes
but we have always flown the western basin. The new pelagic survey being
conducted as we speak this year may shed some light here.  Are they being
more mobile or with gobies and such less mobile.  Both could effect what we
see.

Wintering numbers have never been recorded in anything close to what we
count on Lake Erie. It is believed they, unlike the Common Merganser, winter
far off the Atlantic and Gulf coast beyond aerial surveys and shore
observers.

So is it an illusion, have they changed staging behavior, is there a decline
and if so is it contaminants from the Great Lakes effecting reproductive
potential or some other undocumented problem. We are seeing fewer birds and
they can't hide from the aircraft. Let's see if the pelagic surveys pick
them up albeit later then we are use to.

Mark Shieldcastle
retired Waterfowl Biologist
Research Director
Black Swamp Bird Observatory
Oak Harbor

______________________________________________________________________

Ohio-birds mailing list, a service of the Ohio Ornithological Society.
Our thanks to Miami University for hosting this mailing list.
Additional discussions can be found in our forums, at www.ohiobirds.org/forum/.

You can join or leave the list, or change your options, at:
http://listserv.muohio.edu/scripts/wa.exe?LIST=OHIO-BIRDS
Send questions or comments about the list to: [log in to unmask]