Fall 1991 was among the most outstanding seasons ever for rarities in Minnesota, although some birds lingered only briefly. Highlights included three first state records, two of which occur only as casual species throughout most of North America! The total migration at Hawk Ridge in Duluth was 85,796 hawks, the highest ever. By the end of the period, a record invasion of Northern Hawk Owls was well underway and an unprecedented "double" invasion of Great Gray Owls in two consecutive winters had begun.

Not since 1974, when four first state records appeared that fall, have so many species been recorded in Minnesota for the first time during a single season (The Loon 56:165-66 and 63:286). In addition, the total number of casual/accidental species was more than twice the average number recorded in fall during the previous decade. Several of these (Pacific Loon, Iceland Gull, and Scissor-tailed Flycatcher, e.g.) were represented by multiple individuals. An "unofficial" review of all records for casual/accidental species during the previous decade reveals the magnitude of this season's influx of rarities.

Attempts to correlate specific records of rare birds with weather phenomena are filled with uncertainty. The weather in Minnesota during the fall of 1991 was certainly bizarre. Temperatures were just below average during most of the season until heavy snow cover throughout eastern Minnesota held November temperatures well below normal in many areas; for example, November was 8.7 degrees below normal in the Twin Cities.

Precipitation was generally above average, although isolated pockets of low moisture persisted. Duluth experienced flooding after a series of storms in early September. October and November were both the "snowiest" ever recorded in the Twin Cities. Still, it was a relatively mild season until a cold snap in mid-October. A variety of warblers and Chimney Swifts could still be found along Lake Superior's North Shore during the last weekend in October. However, birds and birders were confronted with seasonal reality when an intense Halloween storm dumped record amounts of snowfall across much of the state. The Twin Cities received over two feet of snow and northeastern Minnesota more than three feet of snow, while areas to the south were clobbered by freezing rain and sleet. Overnight temperatures were suddenly near zero. Although a gradual warming trend melted most of the snow by Thanksgiving, "Son of Mega Storm" dumped another one to two feet of snow across a wide swath of eastern Minnesota in late November. The Twin Cities had received over 55 inches of snow by the end of November, well above the average of 49.2 inches for an entire winter!

Some of the casual species recorded this season may eventually prove to be welcome additions to the list of regular species in the state, such as Pacific Loon, Ross's Goose, Lesser Black-backed Gull, and Scissor-tailed Flycatcher. It is also interesting to consider some of our records within a regional or continental context. Reviewing reports of Red Phalarope and Vermilion Flycatcher from other states for example, in American Birds, actually enhances the importance of such outstanding discoveries in Minnesota, since impressive numbers of individuals were recorded out of range. Regional reports do sometimes suggest that a species may have been "missed" by observers (e.g., many Sabine's Gulls were recorded in nearby regions this season, but not in Minnesota).

It is difficult to single out records for special comment this season and impractical to discuss them all. The Mississippi Kite at Hawk Ridge Nature Reserve in Duluth was the first for northern Minnesota and especially rewarding for the observers, all of whom have contributed endless hours to the educational and scientific endeavors there. Similarly, Steve Carlson's dedication to a daily census of warbler migration through the Twin Cities was justly rewarded on 31 August when he discovered the third state record of Black-throated Gray Warbler at Lakewood Cemetery in Minneapolis. One of the first state records this season, a Fork-tailed Flycatcher in Duluth, was "expected" (to the extent that accidental species can be anticipated) but was most uncooperative since it remained there for only two minutes. The Hoffmans' discovery of a fourth state record Purple Sandpiper in Grand Marais culminated an incredible season there, during which they made the initial identification of two first state records (Fieldfare and Anna's Hummingbird) and established these records with solid documentation. The steady appearance of rarities in Grand Marais set into motion a steady stream of observers, migrating up and down the North Shore of Lake Superior in October and November. It was a memorable season in many respects and the litany of this season awaits your study and pleasure.