This has been an interesting discussion of a subject that I have followed for some time. After Mark Shieldcastle's succinct summation, I've been looking for a way to contribute. I'll begin by answering John's call for some numbers. Here I provide a brief annotation through the years of what little we know. In the following series, please take note of the dates when offered, as well as the respective basin of Lake Erie. Briefly, Lake Erie is comprised of 4 major baythmetric basins, the Western, Sandusky, Central, and Eastern; each quite different from the other in depths, bathymetric features, temp. regime, wave action, and other characteristics. I strongly recommend that every birder wishing to understand something of the waterbird usage of Lake Erie make a point of studying Lake Erie bathymetrics ... here is a good place to start ... http://www.ngdc.noaa.gov/mgg/greatlakes/lakeerie_cdrom/html/e_gmorph.htm In practice, the Western and Sandusky Basins are sufficiently similar avifaunally that observations from the two are typically lumped together in the literature. However, for a few species including Red-breasted Merganser it could be instructive to partition out these records. Any review of the status of a species need start with Bruce Peterjohn's accounts within his two editions of The Birds of Ohio. I'll leave the reader to those specifics but note here his statement that " the huge flights within the Central Basin were not evident until the 1960's". 1960's: The earliest of these huge numbers of which I am aware is that of the 112,000 est. by Edward Bosak 14 Nov 1968 within the Western Basin (in Trautman & Trautman, Birds of Western Lake Erie 2006). 1970's: Reports of this magnitude seem to remain sporadic until 1977-78 although this may be an artifact of reporting. As John Pogacnik pointed out, there is nothing in the CBC record to reflect this increase as the flights or staging events subsided shortly after the first few days of December. By 1978 we saw the species top out at 250,000 when Jim Fry and the Hoffmans noted that number off Huron (Sandusky Basin) 19 Nov. We also now see concentrations farther east in the Central Basin around 1 Dec such as the 4000 off Cleveland in 1979 (Bill & Nancy Klamm). [about this time, a professorial type from CA writes a letter to the editor (I think Am. Birds but my recollection is sketchy) refuting even the possibility that these numbers could be estimated on a lake ... apparently unaware that these were flights past a given point lasting 2-6 hrs. At a snooze pace of a flock of 10 birds every 10 secs (most anyone can count 10 birds in 10 secs) this adds up to 3600 birds per hr and before long you've got in excess of 20,000. Now triple that pace and add a second stream of birds a few hundred yards farther from shore, and do the math. Wonder what he'd make of Bruce Peterjohn's remarkable evening flight of 100,000 in the space of 10 minutes as cited in both editions of The Birds of Ohio.] This approximate population level was to be noted by several different observers over the next 15 years before a gradual drop off to today's levels, a drop-off of an order of magnitude. 1980's: From John Poganick we know a quarter million was once more est. for the peak flight past Vermilion (at the cusp of the Central and Sandusky Basins) in 1984. That year the secondary peak of Dec birds settling off Cleveland reached 10,000 on the 5th (Tom LePage). For my part, my first hand experience came Nov 1985 covering the Huron to the Conneaut collectively over several days accounting for about 140,000. It was 2 weeks later that an aerial survey of the Western Basin estimated 210,000. It remains a debate in my own mind whether these were overlapping or separate concentrations. In 1987, a census from Lorain to Eastlake produced 145,000 birds (in the Cleveland Bird Calender). Keep in mind not all years saw these high counts but seeing tens of thousands certainly was the norm. In 1988, Larry Rosche wrote of that year's Nov flock "The enormous flock of 100,000 Red-breasted Mergansers along the Cleveland Lakefront was not out of character for the species". For all these glimpses at what was certainly a dramatic phenomenon, we remained largely ignorant of what brought the species here, and what governed behaviour once along the south shore of Lake Erie. In something of an understatement Peterjohn (1989) was to write "despite careful observations from shore, our understanding of their movements is poor." It has not improved since. That same year I was intrigued by the question of just how many are along the south shore at one time. In 1989, I coordinated the Lake Erie Waterbird Survey modeled after something in the Hamilton/Toronto area. This 12 Nov count, involving about 15 observers from Huron to Conneaut, produced 173,000 birds including 103,000 off Cleveland and 54,000 off Lorain. 1990's: In 1990, I lucked into a flight off Old Woman Creek, (adjacent to Huron) that lasted 2.5 hrs numbering 98,000 birds. Later on the 25th, in same county, Kirk Alexander had 100,000. Another 27,000 were reported off Cleveland. A year later, we read in The Cleveland Bird Calendar that "numbers defied calculation" off the Central Basin while Brock in North American Birds reported 220,000 for 14 Nov at Sandusky (Sandusky Basin). And in 1993, the 120,000 off Erie 8 Nov (Kirk Alexander) coupled with 40,000 just west of the Cuyahoga R. (Bill Klamm) suggested species was still doing well here. In 1994, few concentrations were reported but scattered flocks accounted for only about 97,000 birds (no more than 40,000 off Erie County 27 Nov). 1995 was strong with a Lake County record 75,000 passing Fairport Harbor ... but otherwise the species drew little attention from elsewhere. 1996: I had 42,000 off Huron 20 Nov with various flocks of 4000 to 10,000 noted elsewhere in the literature. 1999: I matched my 1996 count of 42,000 off Old Woman Creek 7 Nov, while John Pogacnik had almost 24,000 off Lakeshore MP 25 Nov. 2000: 24,000 are reported off Cleveland 12 Nov and Tom and I have the 12,900 from Kelleys Island (virtually all as a distant movement off Marblehead heading west). The present decade: 2001: Joe Hammond reports 50,000 off Sherod Park 11 Nov but few other reports are received. 2002-03: generally reports are 10-15 thousand max, although Bill Whan may fill in gaps here as those issues of The Ohio Cardinal are not with me here in Lawton. 2004: The last year for which I have a sizeable observation, a flight of 37,000 off the beach at Magee Marsh 11 Nov ... my only such observation for the Western Basin. I think most readers can judge the years since from personal experience and the reading of this listserv. It should be noted that the estimates I cite are from trusted observers where their counting methods were known or otherwise corroborated. By the way, in every instance I observed a flight it was E to W. And every instance of settled concentrations they were either in the immediate vicinity of a hot water outlet or near the mouth of a river where effluent waters mix with those of Lake Erie. I consider this a littoral species on Lake Erie* and would be surprised to find it out in open water in any numbers but with one exception ... that being along the Pelee-Lorain ridge that separates the Sandusky Basin from the Central Basin. *In 2 fall seasons, 1984,1985 at the height of the species' prominence along the south shore, I counted waterfowl daily along the north shore in the Eastern Basin. At the tip of Long Point, ON through Oct and Nov, while deep water ducks such as Long-tailed Duck (tens of thousands), and scoters (thousands) were encountered in large numbers, it was exceptional to see more than a few hundred Red-breasted Mergansers. High counts of 1800 to 2000 were had only from shallower inland embayments. I offer this up not for the questions it will answer ... likely none ... but perhaps to hone the questions we may ask and otherwise fuel further speculation. cheers Vic Fazio Lawton, OK ______________________________________________________________________ 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]