Posted on behalf of Skye Haas
Hey Dave,
Can you post this to the Ohio list-serve for me?
~Skye
Hello all,
I have been following this discussion with interest. I recently
authored the Red-breasted Merganser species account for the upcoming
Michigan Breeding Bird Atlas II. In data analysis, it was noted that
the breeding population of RB Mergs have been steadily declining since
the 80s in the upper Great Lakes, particularly on Lakes Michigan and
Huron. The Beaver Island chain used to be a major breeding location
for most of the 20th Century (save for a decline in the 70s due to
organochlorine chemicals), but has been reduced to only a handful of
pairs. Populations in Green Bay in Wisconsin have also experienced
significant declines, and breeding numbers have been declining in
Ontario on Lake Huron.
One possible suspect in the modern declines may be the result of lake
eutrophication and outbreaks of botulism-E. In northern Lake Michigan
in fall 2007 researchers found 3000 botulism-E killed waterbirds of
which 6% were RB Mergs. And in fall 2000 just under 2500 Red-breasted
Mergansers washed up dead on Lake Ontario from a similar outbreak
event.
Botulism-E is instigated by non-native invasive species- mass amounts
of Dressina mussels (zebra & quagga) filter the water column allowing
for exaggerated blooms of native cladophora algae. As the cladophora
senescence and dies, sections of the lake become anaerobic allows
botulism-E to thrive. Botulism-E easily infects gobies and other small
prey items which are then consumed by the mergansers and other
waterbirds.
~Skye Haas
---------- Forwarded message ----------
From: Skye Haas <[log in to unmask]>
Date: Tue, Dec 1, 2009 at 9:11 PM
Subject: RB Merganser decline in the Great Lakes
To: Dave Slager <[log in to unmask]>
Hey Dave,
Can you post this to the Ohio list-serve for me?
~Skye
Hello all,
I have been following this discussion with interest. I recently
authored the Red-breasted Merganser species account for the upcoming
Michigan Breeding Bird Atlas II. In data analysis, it was noted that
the breeding population of RB Mergs have been steadily declining since
the 80s in the upper Great Lakes, particularly on Lakes Michigan and
Huron. The Beaver Island chain used to be a major breeding location
for most of the 20th Century (save for a decline in the 70s due to
organochlorine chemicals), but has been reduced to only a handful of
pairs. Populations in Green Bay in Wisconsin have also experienced
significant declines, and breeding numbers have been declining in
Ontario on Lake Huron.
One possible suspect in the modern declines may be the result of lake
eutrophication and outbreaks of botulism-E. In northern Lake Michigan
in fall 2007 researchers found 3000 botulism-E killed waterbirds of
which 6% were RB Mergs. And in fall 2000 just under 2500 Red-breasted
Mergansers washed up dead on Lake Ontario from a similar outbreak
event.
Botulism-E is instigated by non-native invasive species- mass amounts
of Dressina mussels (zebra & quagga) filter the water column allowing
for exaggerated blooms of native cladophora algae. As the cladophora
senescence and dies, sections of the lake become anaerobic allows
botulism-E to thrive. Botulism-E easily infects gobies and other small
prey items which are then consumed by the mergansers and other
waterbirds.
~Skye Haas
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