jlHE CHANGING SEASONS: OSCILLATIONS 
Surface Weather Map at 7 :00 A.M. E.S.T. 
Figures 3, 4. Surface weather maps for 5 and 6 April 2009. This fast-moving low-pressure system grounded aerialists such as swifts 
and swallows by the thousands in the Southeast, including an apparent Black Swift in northern Alabama at Leighton and possibly a 
White-throated Swift at Santa Rosa, Florida, on the Gulf coast halfway between Destin and Panama City. But the early date for the 
Black Swift suggests that it was not a western bird but instead perhaps a Caribbean breeder that overshot its breeding grounds but 
was grounded (with thousands of swallows) when southerly winds shifted abruptly to northerly. Map courtesy of and © the National 
Centers for Environmental Prediction, National Oceanic and Atmospheric Administration. 
Figure 2. This male Black Swift made repeated passes over the 
visitor center at Point Pelee National Park on 17-18 (here 17) May 
2009, providing a second record of the species for Ontario. There 
are scattered reports of Black Swifts (and large, dark swifts) in 
eastern North America, but this individual was the first to be con- 
firmed by photograph. Photographs by Brandon R. Holden. 
would be the first, pending acceptance, for 
those states, though both were sight records. 
Single Black Swifts at Point Pelee, Ontario 17- 
18 May (Figure 2) and Leighton, Alabama 7 
April would both be seconds. And Florida had 
its first White-throated Swift, an ailing bird 
found on a condominium balcony at Navarre 
Beach 9 April (not the first Florida mega-rari- 
ty to be found on a condo balcony!). Interest- 
ingly, the Alabama swift was associated with a 
fast-moving low-pressure system (Figures 3, 
4) with a high-pressure air mass just west of it 
that passed swiftly eastward, bringing norther- 
ly winds to the states along the northern edge 
of the Gulf of Mexico. Steve McConnell writes 
of this front “the passage of a strong cold front 
6 April through northern Alabama, preceded 
by unseasonably warm weather, resulted in 
thermometer readings the morning of 7 April 
around 11° C lower than the previous day. 
This temperature change brought thousands 
of insectivores such as martins, swifts, and 
swallows to forage low over almost any stand- 
ing water.” Looking at this system, one is 
tempted to suggest that the White-throated 
Swift might also have been grounded by it: 
Santa Rosa is in what some call “Southern Al- 
abama,” that part of Florida that lies south of 
Alabama, and the bird was discovered just two 
days after the Black Swift. The storm system, 
which gathered steam 3 April in the central 
Rockies before intensifying and plunging 
southeastward into the Great Plains (western 
Kansas) the next day, certainly had enough 
strength to move even strong-flying birds. But 
Black Swifts arrive in the Rockies in May — late 
May, usually (or even June) — not in early 
April! So it seems unlikely in the extreme that 
this bird would have been a western Black 
Swift, of subspecies borealis. In the Greater 
Antilles, Black Swifts of the nominate sub- 
species begin arriving in March, so perhaps 
the bird was from a West Indian population, as 
several tentative Florida reports of large, dark 
swifts are believed to be? Ah, the perils and 
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NORTH AIWERICAN BIRDS 
