After the snowiest November on record, a particularly long winter was expected, but instead this season was one of the warmest ever, and very little additional snowfall was received. December began cold in the state with the Twin Cities recording a record low temperature for the date (-11°) on the 4th, but the following week was warmer, with temperatures as much as 5–10° above normal all across the state. After freezing rain across much of the state on the 12th, the weather turned cold and windy, just in time for many of the CBC's (lowest temperature on a CBC was -20° at Bemidji). The rest of the month was above average, with temperatures as much as 10–20°+ above normal. Although Christmas Day was sunny in the Twin Cities, a record setting 14 sunless days (350 hours) followed as fog and thick clouds blanketed most of the state and temperatures hung in the 30s. This unseasonably warm weather continued until mid January when a period of below zero readings set in, with a low of -14° in the Twin Cities on the 15th, and -29° at International Falls. These were the lowest temperatures all season. Despite this cold spell, the average temperature in January in the Twin Cities was 21.9°, 10.7° above normal. During early February, temperatures were again as much as 10–20° above normal, and as high as the mid 50s in southwestern Minnesota. Although the second week in February was more “normal” with lows in the 0s in the south and as much as -29° at International Falls in the north, by the third week temperatures were once again 10° or more above normal. Weekly highs throughout the state and throughout most of the winter were generally in the 30s and 40s.

A total of 140 species were reported this season, similar to the 138 and 141 recorded the past two years, but less than the 144 and 146 reported 3 and 5 years ago. No doubt the early winter weather accounted for the absence of many birds, including such normally late lingering waterbirds as Common Loon and Northern Shoveler. Also missed were the thousands of Common Mergansers and Tundra Swans which are often still present at the beginning of the period in the lower Mississippi River Valley. Conversely, this weather probably accounts for the record number of White-throated Sparrows in the state in December, since the early snows caught many birds off guard. Other unusual winter species lingering into December included Chipping Sparrow, Rose-breasted Grosbeak, Hermit Thrush, and Ruby-crowned Kinglet. Brewer's Blackbirds and Common Grackles were both reported overwintering unusually far north.

The 1991 record fall for rarities in Minnesota continued with that first state record Anna's Hummingbird lingering until December 1st in Grand Marais. The highlight of the season came in December on the Mississippi River in St. Paul where one, and then (remarkably) two, Ivory Gulls were found, attracting interested birders from all over the state. The many birders in this area were also treated to an adult Great-blacked Gull, two Thayer's Gulls, an Long-tailed Duck, and a concentration of nearly 3,000 Common Goldeneyes. Of the large numbers of gulls of six species wintering in Superior, Wisconsin, Minnesota managed to record the first-winter Iceland and Great Black-backed Gulls later in the period. Fergus Falls once again turned up a rare winter find with a wintering Harlequin Duck.

After the Ivory Gulls disappeared, birding in the south was notably slow, with many observers reporting a general lack of birds, especially at feeders, and several observers even stated that this was their poorest winter ever for birds. Many normally common species were reported in record or near record low numbers, including American Tree Sparrows, Dark-eyed Juncos, American Robins, Cedar Waxwings, and Red-breasted Nuthatches. Some have suggested that the early snows forced most of these birds farther south.

But observers traveling into northern Minnesota were treated to this winter's second highlight, the simultaneous invasion of Great Gray, Snowy, and Northern Hawk Owls. This unprecedented invasion was especially noteworthy since all three species appeared in record numbers during the same season, and since Great Gray Owls were seen in record numbers for the second year in a row. Most observers who traveled into the northeastern and northcentral regions were treated to multiple sightings of all three species. In past invasions, other avian predators have invaded at the same time, but very few reports of Boreal Owls were received, and only average numbers of Barred Owls were reported. A record number of Gyrfalcon reports were received, including one overwintering at Duluth for the first time in seven years. Also noteworthy were the record number of stray Golden and wintering Bald Eagles, both unusually far north of their normal winter ranges. Rough-legged Hawks and Northern Shrikes were also widespread in above average numbers all across the state.

Most winter finches that occurred this season were confined to the north. Only here were Pine and Evening Grosbeaks seen in any numbers, and the redpoll invasion was also mostly confined to the north. A record number of Hoary Redpolls were reported in the north, while only two south reports were received. Other winter finches were scarce statewide, with virtually no crossbill reports, and near record low numbers of Pine Siskins and American Goldfinches, even in the south. The only winter finches of note were the large number of House Finches wintering in some localities.

Early spring migration was noted for many species during the warm weather in late February. Red-winged Blackbirds, Killdeer, Eastern Bluebirds, Herring Gulls, thousands of Lapland Longspurs, and many of species of waterfowl including a flock of Snow Geese (over Coon Rapids on the 29th), were all recorded moving north at this time.

This report was prepared from the reports of 65 seasonal contributors, 46 CBC's, and a few other individuals. Although this report would not be possible without the many observers that took the time to fill out seasonal reports, no matter how brief, it is unfortunate that some of Minnesota's most active birders did not send in reports, and that many records of unusual species did not provide sufficient details to be included in this report. In the interest of making this report even more complete, and learning more about our winter avifauna, contributors are encouraged to be more specific on their report forms and include information on number of individuals, early or late migrant status, and overwintering status if known. Local observers are in a much better position to judge a species' status in their area than this compiler. The many reports of individual birds on CBCs and not in seasonal reports suggest inadequate coverage from many areas. Although most of the counties in the far north were at least partially covered this season, virtually no reports were received from the entire band of counties on either side of the boundary between the north and south regions, and most of the central and west central regions continue to be inadequately covered. Many common species were recorded in far fewer counties than normal, and some of this winter's invaders (such as Northern Shrike and Rough-legged Hawk) were probably more widespread than the records indicate. Despite these “complaints,” all contributors can be proud of the following report of a remarkable season.