species endured great hardships in part due to 
the [severe] tidal events: out of 75 monitored 
pairs, only a single American Oystercatcher 
chick fledged on the entire Georgia coast.” 
(However, several regions, from Ontario to 
Florida, reported good success with nesting 
terns and plovers, particularly at locations 
where policing of nesting areas was em- 
ployed.) Heavy rains (and some hail) and 
flooding 10 June and 15-16June had negative 
impacts on many nesting species in Missouri, 
and heavy rains during the latter window also 
hit Bismarck, South Dakota. Cool weather 
meant that “few insects were available” in the 
northern Great Plains, according to Ron Mar- 
tin, which probably further suppressed nest- 
ing activity and success. 
Northern exposure 
Because this column does not look as much at 
long-term trends as seasonal snapshots, we 
admittedly miss some very important phe- 
nomena that probably have more to do with 
the fluctuations in bird numbers we observe 
than do many of the storm fronts and ocean 
anomalies we often consider here. Historically, 
too, the northern half of North America, the 
lightly settled boreal forest and tundra, has re- 
ceived less attention in this column than the 
southern tier of Canada and the Lower 48 
states because our observers and contributors 
live mostly south of 50° N latitude. 
In the abundant discussions about climate 
change, melting ice, and sea level rise, the 
rapid changes in the boreal forest — especially 
the increasing tolls taken by drought, fires, 
and insects — have not received as much at- 
tention as they deserve, although Alan Alda’s 
Scientific American Frontiers did a good job of 
summarizing the impacts of these plagues for 
the television audience about five years ago. 
In the current year, 2009, the media brought 
this subject to world’s attention, first in 
March, when scientists gathered in Copen- 
hagen, Denmark at the conference entitled 
“Climate Change: Global Risks, Challenges, 
and Decisions,” then in mid-December at the 
United Nations Climate Change Conference, 
which, unfortunately, failed to produce a con- 
sensus in the form of a ratified agreement to 
mitigate global climate change. 
The Intergovernmental Panel on Climate 
Change, the scientific working group spon- 
sored by the United Nations, has analyzed nu- 
merous studies that investigate the relation- 
ship between wildfires and warmer, drier con- 
ditions and found that scientific evidence 
supports a positive correlation (IPCC 2007). 
And there is no question that forest fires have 
increased in North America’s West and North 
in recent decades. In Canada, for instance, the 
area burned in the 1990s was double what it 
was in the 1970s (Amiro et al. 2003). Of 
course, the northern forests extend across 
Eurasia as well. American researcher Amber 
Soja of the United States National Institute of 
Aerospace, working with teams in Siberia at 
the Sukachev Institute of Forestry in Krasno- 
yarsk, notes that all but two of the past ten 
summers have witnessed extreme wildfires 
across central Siberia (Soja et al. 2007, 2009). 
Warmer summers are part of the reason for 
increasing wildfires: average summer temper- 
atures have increased between 2° and 4° F 
over the past hundred years, more than twice 
to four times the average increase in temper- 
ate zones over the same period. Warmer cli- 
mates dry the forests, lengthen the fire season, 
and have more storms with lightning, which 
ignite more fires. 
While fires are part of the natural cycle in 
which boreal plants and animals have existed 
for thousands of years, the frequency and size 
of these fires have increased so starkly as to 
upset this balance. The logging of tens of mil- 
lions of acres of boreal forest has produced 
more fragmented, younger, and more even- 
aged forests, and the additional loss of mature 
forest to frequent and often massive fires has 
become a dire concern for the conservation of 
wildlife, including many bird species, from 
Black Scoter to Rusty Blackbird. When 
healthy, these forests serve as “sinks” (net ab- 
sorbers) for carbon dioxide, one of the princi- 
pal gases associated with climate change; but 
decaying and burning wood releases tons of 
carbon dioxide, as does burning peat, the car- 
bon-rich substrate that underlies the forest. 
The fear of many scientists is that we may still 
underestimate the “domino effect,” or posi- 
tive biospheric feedback, by which more fires 
lead to an accelerating rate of liberation of 
carbon dioxide, which in turn leads to even 
more extensive fires. By Canadian Forest 
Service estimates, the country’s forests have 
already lost their role as a carbon sink, one 
that absorbed about 55 million tons of CO 2 
annually a decade or so ago, to a carbon 
source — now producing a net of perhaps 245 
million tons per year. 
Possibly accelerating this process, too, are 
more frequent outbreaks of beetles and other 
insects in recent years, which provide more 
fuel in the form of dead and dying trees, which 
causes fires to burn more intensely. The epi- 
demic of Mountain Pine Beetle in the Lower 48 
states, from Colorado to Washington state, has 
killed 2.6 million hectares (6.5 million acres) 
THE CHANGING SEASONS: THINK PINK 
of forest. Across the border, in British Colum- 
bia, beetles have killed 14 million hectares (35 
million acres) of forest, and they are expected 
to kill 80 percent of the Canadian province’s 
Lodgepole Pines before the outbreak subsides. 
Farther north, other insects, among them 
Northern Spruce Engraver, Aspen Leaf Miner, 
and Willow Miner have shown increasing ac- 
tivity during the recent period of warming. In 
the Yukon, Spruce Bark Beetles have eaten 
their way through 400,000 hectares (1 million 
acres) of woodland, and over 1.2 million 
hectares (3 million acres) in neighboring Alas- 
ka since 1989. The Yukon has not yet recorded 
Mountain Pine Beetle, but an outbreak there 
could devastate native pines, which may have 
little resistance to this species. 
Although recent studies show a positive 
correlation between warm/dry periods and 
forest fires (e.g., Meyn et al. 2009), the rela- 
tionships between warmer/drier weather, 
fires, and beetle outbreaks have not been as 
clearly established. Several paleoecological 
studies have looked back several hundred 
years, using dendrochronological reconstruc- 
tion of historical climate and beetle activity 
(e.g., Alfaro et al. 2010), and found that the 
age and composition of a forest, as well as its 
history of exposure to fires of various types, 
appear to contribute to its susceptibility to 
beetle outbreaks. My own reading of such 
studies does not give me cause for optimism; 
even the best-case scenarios show increases of 
about 50 percent in areas burned in the Amer- 
ican West by the 2050s (Spracklen et al., in 
press), for instance. It is difficult to imagine 
our avifauna in the aftermath of such losses. 
Debates continue to rage on many fronts as 
to the best way to mitigate this rapidly wors- 
ening situation. According to some models, 
fires and beetles are projected to impact a 
Montana-size area of boreal forest by the year 
2020. Carbon dioxide releases from decaying 
wood due to the beetles alone have been pro- 
jected at 270 million tons over that period. 
Some forestry groups advocate more logging 
of northern forests to avoid the problems as- 
sociated with fires and insects, and the forest 
products industry in Canada has increased 
harvests as a result. However, many scientists 
believe that increased logging will unleash far 
more carbon by exposing and dr)4ng the peat 
layer, which would decay and burn more 
readily. In addition, there is growing evidence 
that the even-aged and fragmented forests 
that dominate many landscapes as a legacy of 
logging practices can allow beetles to spread 
more rapidly than they would in an unman- 
aged, natural forest. Forest products, of 
VOLUME 63 (2009) 
NUMBER 4 
553 
