Between 1921 and 1944, it became widely known among ornithologists that the Eastern Kingbird is a breeding summer resident bird in Modoc County, California. It also was susptected to be a breeding bird in Inyo County, so that Ralph Hoffmann's observation could have been an early notification to us that it breeds in the vicinity of Mono Lake?
Yet, David Gaines in his authoritative book, Birds of Yosemite and the East Slope, records the Eastern Kingbird as an "extremely rare vagrant east of the Sierran escarpment." As proof of its rarity, David Gaines records just four records of the Eastern Kingbird. They include one sighting at 6,500 feet elevation at Deschambeau Ponds on June 24-25-1982; one sighting at 6,400 feet near Mono Lake on July 19, 1921 which we know to be the record by Ralph Hoffmann (see above); and lastly at northern Mono Lake at 6,400 feet elevation on July 24, 1978 and August 30-31, 1986.
I am left to ponder and contemplate, as perhaps you are too, why it is that the Eastern Kingbird nests in Modoc County and Inyo County, which are lower elevations of about 3,000 to 4,00 feet, and not in Mono County around Mono Lake. The answer to why more Eastern Kingbirds do not nest in eastern California, east of the Sierra-Cascade Mountains is predictably due to cattle-sheep grazing that rapes the land, particularly in wetlands, called riparian areas. To have more of the beautiful Eastern Kingbird requires elimination of livestock grazing on public lands in California.
In closing, I smile that Eastern Kingbirds can be found at Santa Monica, Mono Lake, Modoc, Shasta Valley, Honey Lake (Lassen County, just north of Reno, Nevada) and eventually it will be recorded at the Ballona wetlands as migrant, perhaps this autumn of 2003. Arnold Small, in his wonderful book, California Birds, reports that it has been recorded on all the Channel Islands except Anacapa and Santa Rosa. Isn't it interesting that Ralph Hoffmann explored these Channel Islands very carefully, but he did not record the Eastern Kingbird from the northern Channel Islands. It remained for later birders, naturalists, and scientists to discover that they migrate through southern California, sometimes stopping in Santa Monica, and sometimes stopping on the Channel Islands of southern California, including Catalina Island.