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 ______________________________________________________________________ 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]