Lake Lowell (aka Deer Flat Reservoir) is in southwestern Idaho 15 miles east of the Oregon State Line. I visited in winter in the mid 1970s and saw a mass of Mallards paralleling the south shore that stretched for most of the lake's 10-mile length. I subsequently learned that the lake was usually setting CBC national highs for Mallards in those years, with numbers counted by refuge personnel in the 500K - 600K range.
I tried to census a mixed-icterid winter roost at Cheyenne Bottoms, Kansas in 1986 and came up with 800,000 birds. Redwinged Blackbirds were predominant, with Common Grackles, Brewer's, BH Cowbirds, a few Yellowheads.
On 11/8/2018 4:16:00 PM, <philliplc...> <philliplc...> wrote:
> Yes I know, Mallards are not very exciting
Memory of the event is distant and foggy, but probably
the largest flock of non-Sooty Shearwaters I've seen in
Oregon was (at least) 6 figures Mallards, I think (?)
on the Columbia near or at Umatilla NWR. This was
on a whirlwind day trip to NE Oregon with Dave Irons
& Fix in the late '80s. Not sure if this was a normal
concentration at that time, but certainly an exciting
spectacle that I still picture occasionally.