Changing Seasons the Winter Season, 1999-2000: Warm Weather and Cross-continental Wonders

As the ravages of La Nifia and global warming draped North America, we were treated to one of the mildest winters on record.Unseasonably warm weather was the norm from coast to coast, from the snowbelt to the sunbelt.As a startling example, consider a 27 December temperature of 68ø1: (20øC)...in Calgary!Much of the north and east experienced slightly more normal weather in January, before a milder February continued the earlier trend.The balmy temperatures of the early winter lured many birds into a false sense of security, and they attempted to winter much farther north than usual, sometimes with tragic results.Dozens of American Woodcocks, for example, perished during a cold snap in mid-January in southern New Jersey; most were underfed and emaciated.Even so, a host of less-hardy species was present this winter, some in Regions far outside their normal range.Perhaps in no group was this pattern better exemplified than in the hummingbirds.Because eastern North America generally hosts but one species, hummingbirds are met with careful scrutiny in that half of the continent, particularly after September, when most Ruby-throateds have departed.This mildest of winters produced a plethora of hummer oddities sprinkled across the East, from multiple Broad-taileds in Louisiana to confirmed Black-chinneds in North Carolina and Tennessee, a Broad-billed in Louisiana, and an Allen's in Texas to the more amazing (and well-documented) find of a Calliope in South Carolina.If global warming is real and will occur as quickly as some fatalists predict, the hummingbird show this winter will look tame ten years from now.GLOBAL WARMING?A counterintuitive trend in this warm winter was the continued presence of numerous redpolls and other winter finches in the northern states, particularly in the Northeast.Furthermore, the East saw its biggest influx of Rough-legged Hawks in decades, with some 30 reaching Connecticut, various others south to North Carolina, and three reaching Florida, the first of the species documented in that state (Fig. 1 ).Not to be outdone it would seem, a Snowy Owl pushed southward to Florida (see the Pictorial Highlights), also furnishing a first record for the Sunshine State.A more ambiguous pattern was the presence of many western wood-warblers in the East, including Audubon's in Massachusetts and Maryland, a Black-throated Gray in Quebec, Townsend's in Virginia and Florida, and MacGillivray's in Massachusetts and New York.Whether the warmth had anything to do with the occurrence of these species is debatable and seemingly unlikely, but the warmth probably did allow many warblers to tarry in the unexpectedly favorable clime, increasing the probability for their discovery by birders.In short, if global warming is occurring or the apparent increased frequency of E1 Nifio events are contributing to changes in species distributions, what exactly can we predict.*A simple prediction could be that warm-water seabirds would appear farther north (see Patten 1998).Also, we might safely hypothesize that landbirds that normally winter in the subtropics would extend their wintering range to the north, as might be happening with the hummingbirds mentioned above or with the marked increase of Rufous-capped Warblers (see the cover), Rufous-backed Robins (see the Pictorial Highlights), Streak-backed Orioles, and other "Mexican" species.But what if a species is showing the opposite pattern?Is it a fluke or does it call into question our very ideas about global warming?A fine example of such an exception is provided by the Yellow-billed Loon.This bird of the high Arctic seemingly expanded its wintering range southward along the Pacific Coast beginning in the mid-1960s (Remsen and Binford 1975).Until the early 1970s, there were but two records away from the Pacific slope, a 1930 partial specimen recovered in New York and a 1944 specimen from Colorado (Phillips 1990).Since the early 1970s, there have been _+150 records for the interior of North America, ranging from inland records from British Columbia and the Pacific states to dozens from the Prairie Provinces, Ontario, and New York south to the Southwest (e.g., Arizona, Texas) Figure 1.Rough-legged Hawks staged one of their largest incursions into the Northeast in decades.Birds reached far to the south of their normal range in the East• with a few providing the first documented rocords for Florida• such as this lightmorph bird near Zellwood• Orange County• 17 February ZOO0.Photographed by Kurt A. Radamaker.

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