rounding humid climates.” 
Because westerly winds coming into Eu- 
rope are rather obviously heavily influenced 
in the “squeeze play” between the relatively 
permanent Icelandic Low and Azores High, 
birders there pay more attention to the NAO 
than do Americans. A “strong” NAO occurs 
when the difference in pressure between the 
two areas is high, producing stronger wester- 
lies (and often more New World bird vagrants 
to Europe and the Azores). But the NAO is 
also thought to influence weather over east- 
ern North America. According to Wikipedia: 
“During the winter, when the index is high 
(NAO+), the Icelandic Low draws a stronger 
south-westerly circulation over the eastern 
half of the North American continent, which 
prevents Arctic air from plunging south- 
ward.” In addition to warmer temperatures, a 
strong NAO increases rainfall in the East, 
which may have the effect of lowering ocean 
salinity and suppressing ocean upwelling. 
Some researchers think that the collapse of 
the cod fishery two decades ago, for instance, 
was related to a strong NAO. As one consid- 
ers the various bird records in the next sec- 
tion — many of which were attributed to 
southwesterly wind flow by regional edi- 
tors — it may be worth keeping this “other” 
oscillation in mind. Though we think of the 
NAO as primarily climatic, the ocean is clear- 
ly influenced, according to extensive Euro- 
pean research, and some researchers attribute 
part of the phenomenon of stronger storm- 
surges in recent decades to a stronger NAO 
(e.g., Ullmann and Monbaliu 2009). Perhaps 
some of our own surges — such as the very un- 
usual, “unexplained” tides that destroyed 
many colonial birds’ colonies on the Georgia 
coast this spring — are partly products of a 
NAO index that is stronger than normal. 
East of Normal 
From Ontario to New England to Prince Ed- 
ward Island, the regional reports detail an in- 
crease in migrant geese that typically winter in 
the central and western parts of the continent. 
In the first part of March, Greater White-front- 
ed and Ross’s Geese put in appearances in 
above-average numbers, and these were 
linked, according to Simon Perkins, to a per- 
sistent westerly and southwesterly airflow 
during this period. Alan Wormington also 
cites one reason for the increase in goose 
numbers; “the widespread adoption of no-till 
farming in recent decades — when waste com 
and stubble remain in farm fields through 
spring — has facilitated an eastward expansion 
of migration patterns for both [Ross’s] and 
other prairie geese.” He notes that Point Pelee, 
Ontario, which had its first record of Ross’s 
Goose only in 1994, recorded minimally 44 by 
10 March this year, with 42 or more elsewhere 
in the province away from Hudson Bay, two of 
which were rare blue-morph birds. (Another 
blue morph was seen at Cap Tourmente, 
Quebec 18 May.) During precisely the same 
window, New England had a flock of 17 
Greater White-fronted Geese at Saugus, Mas- 
sachusetts, apparently of western subspecies 
frontalis. Perkins writes: “The great majority 
of recent Greater White-fronted Goose records 
in the Region have pertained to Jlavirostris, 
from Greenland.” Shortly after these arrived, 
at least 15 Ross’s Geese were found in Massa- 
chusetts (more than twice the New England 
maximum count), Maine had its second, and 
Prince Edward Island had three singles, that 
province’s third through fifth records, (Blake 
Maybank notes: “Oddly, Nova Scotia remains 
the only one of the four Atlantic provinces 
without a record of Ross’s Goose.” (Any takers 
on odds that 2010 will be the year?) 
If we search for a broader pattern, we find 
that a total of ten Greater White-fronted 
Geese in upstate New York included a group 
of eight at Oak Orchard Wildlife Management 
Area 8 March, likely part of the eastward shift; 
and the species was found in above-average 
numbers in Quebec (44) as well. But a re- 
markable 16 in Westmoreland County, Vir- 
ginia 8 May set not only a high count but 
were also very late. It was not clear which 
subspecies was (or were) involved in these re- 
ports; we should strive to determine this 
whenever possible with this interesting, dy- 
namic species. Unlike Ross’s and pink-billed 
Greater White-fronted Geese, Cackling Goose 
was not as widely reported east of usual areas; 
New England had just seven and New Jersey 
three, but New York had about 78, almost en- 
tirely upstate. Two in late May at Labrador 
City were the first for the province of New- 
foundland and Labrador. Barnacle Geese were 
likewise not in the numbers we have come to 
expect lingering from winter; only a single 
was reported, at Victoriaville, Quebec 19 
April-9 May. The weather maps in the New 
England report seem rather compelling: the 
episodes of strong southwesterlies surely 
could have caused an eastward shift in move- 
ments of prairie-wintering geese, as Perkins 
suggests. And even though, as Wormington 
points out, the trend is toward increasing 
numbers east of past wintering areas and past 
migration routes, the sharp, simultaneous 
spike in records in a short period in New Eng- 
land, which lies well east of migration routes. 
THE CHANGING SEASONS: OSCILLATIONS 
suggests something like a “fallout” of frontal- 
is Greater White-fronted and even of Ross’s, 
which is more expected in the region, if not in 
such numbers and not during this time frame. 
If the southwesterlies were a proximate factor 
in shifting the prairie goose flight eastward, 
could the North Atlantic Oscillation be a fac- 
tor in the strong southwesterlies? 
In the spring out West, the annual appear- 
ances of passerines that breed in the East or 
boreal forest are carefully catalogued by bird- 
ers, who have, over the decades, documented 
trends that mirror the birds’ population 
trends but are not clearly or directly correlat- 
ed to distinct weather phenomena (e.g., Pat- 
ten and Marantz 1996). Western birds do ap- 
pear in the East in spring, of course, but pat- 
terns of occurrence seem sketchy and usually 
weak: where the West might get two-dozen 
Prothonotary Warblers in a “good” spring, a 
haul of three Townsend’s Warblers in an area 
of equal size in the East is about as many as 
one might expect. 
One might think, given the general preva- 
lence of westerly winds over the continent, 
that western birds’ appearances in the East in 
spring would be quite common, if weather 
systems are the chief proximate cause of such 
displacements (see Brinkley 2001 for more 
comprehensive discussion). For autumn va- 
grants to Massachusetts, Veit (2000) holds 
that “movement behavior does not vary much 
between years” and that “large numbers of va- 
grants are the consequence of large numbers 
of young being produced.” Autumn vagrants 
in the East tend to concentrate in coastal ar- 
eas (oceans, bays, large lakes) and in urban 
“traps” — micro-habitats that are a far cry 
from the oases of wooded habitat in the West 
that are so legendary for producing eastern 
vagrants in spring. Indeed, many have argued, 
in this journal, that the more lushly vegetated 
East simply conceals western vagrants, which 
are simply more dispersed, less concentrated 
because they can be. Others have suggested 
that because few truly western species make 
long water crossings in spring migration, 
their tendency to get caught up in unfavor- 
able weather systems is far lower that east- 
ern/boreal forest species’. Still others have 
suggested that migration distances and migra- 
tion strategies in many western passerines dif- 
fer sufficiently from eastern ones, so that dra- 
matic “errors” associated with appearances of 
vagrants are simply fewer. Probably because 
of the relative paucity of data, no “eastern” 
equivalent to the ground-breaking paper of 
Patten and Marantz (1996) exists, so we con- 
tinue to hazard conjecture here. 
VOLUME 63 (2009) • NUMBER 3 
373 
