Finally, snow. Enough to shovel.
But nature’s first attempt to dump a
lasting white calling card on Toronto Friday might be too little, too
late for local critters, bugs and plants that have evolved to tolerate
frigid, snowy Canadian winters — not tennis-playing temperatures in
December and January, which put their survival at risk.
“We don’t need statistics to tell us
something odd is happening,” says Ryan Ness, manager of water resources
at the Toronto and Region Conservation Authority.
His evidence, besides not needing
boots until now? Ponds and streams usually covered weeks ago with solid
ice — which protects resting fish with a stable environment buffered
from very cold air and calorie-burning turbulence — are open water.
Odd, too, are the extreme
freeze-and-thaw cycles of the past few two months. For this weekend, for
example, forecasters were predicting thermometers would plunge into
bitter below-zero range, then rocket back up to 5, with rain, on
Tuesday.
Environmental experts say temperature
swings stress out animals, invertebrates and plants used to one long
winter freeze with a gradual warm, rainy melt into spring.
From wood frogs and salamanders to
swallowtail butterflies and seed-bearing trees, species can die (lack of
a snowy insulating layer means greater exposure to cold temperatures
for meadow voles, for instance) or produce stunted offspring.
Trees, in particular, can be
affected. While mild weather mitigates damage like broken branches from
heavy ice, temperature swings can stunt reproduction at a time when
provincial tree canopies, already considered too sparse, are being
beefed up with millions of plantings.
“It’s funny, a lot of people will
say, ‘Ha, this is great, it’s six degrees out today and I only have to
wear a light coat,’ ” says forester Rob Keen, CEO of Trees Ontario,
which helps to create and restore forests through seed collections when
trees flower in spring.
“What we’ve seen in the last several
years with the milder springs are the trees start to put flowers on
earlier. Then we’ve seen frosts come in, killing the flowers and
therefore, killing the seed production. It’s really detrimental to our
restoration efforts.”
Okay, we’ve gotten this far without mentioning climate change — but hold that thought.
Periodic stretches of unusual weather
are “quite within the tolerance” of creatures that have adapted to
habitat changes over the eons, says Ralph Toninger, manager of habitat
restoration at Toronto and Region Conservation Authority.
“It would really take something like
successive years of warm weather, like if we had four straight winters
of warm weather like this, before you’d really start to see an impact on
trees and native wild life,” Toninger explains.
That brings us back to climate change. Is this Year One of a hotter, more disturbing pattern or simply a one-off occurrence?
Bill Parker, a research scientist
with the Ministry of Natural Resources Ontario Forest Research Institute
in Sault Ste. Marie and a climate change specialist, thinks the GTA is
just one of many areas that may be starting a gradual warming.
“This is obviously an abnormally warm
winter so far and I would say that this type of weather is consistent
with what is projected to occur in the future under climate change,” he
says.
“This will become more and more common, it’s believed.”
Until Friday, the GTA winter has been
balmy experience. No snow crunching underfoot, no icy pellets sparkling
in trees or prolonged freezes to magically transform ponds into skating
rinks. Even Friday’s “storm” mellowed out when it hit, spitting out a
few greasy centimetres of wet snow during the morning rush hours.
Without a substantial blanket of snow
and ice, some types of fish are at risk for starvation, and their
breeding areas can be damaged..
“When you don’t get a lot of snow
buildup, what you don’t get in spring is the big rush of water that
flushes out all the accumulated sediment and cleans up gravel in areas
where fish spawn,” Ness says.
“It’s a pattern that fish are used
to. Some fish spawn at that time of year (when water levels are high) so
they go to where they need to go to spawn.
“Now, because a lot of precipitation
falls as rain instead of snow, it runs off into water courses and
increases flow almost all winter. So you get periodic small flows
instead of one big one in spring.”
Christine Tu, a rivers and streams
specialist at of the Toronto and Region Conservation Authority, says
solid ice cover provides a low-turbulence environment for fish in
medium-sized streams during winter months, when their metabolism
decreases because food sources are scarce. Fish tend to group in deep
pool areas of streams, feeding and moving very little, but without ice,
there can be turbulence forcing the fish to move, Tu explains.
Another problem in this scenario is
frazil ice, which is columns of swirling ice crystals that can reach
down into a creek channel. Frazil ice can nudge fish from their quiet
refuge pool, which makes them expend energy.
“You’ve got this double-edge sword,”
Tu says, “not enough food and higher metabolism from movement they’re
not used to and essentially, you have a starvation condition.”
(Fish can also die from a lack of
oxygen. That’s usually in ponds where ice cover doesn’t break soon
enough and fish have depleted the oxygen supply.)
Though the absence of snow can be a
bountiful time for animals like deer which can forage freely, Toninger
says it can also adversely affect a hunter-prey relationship.
Voles, for example, live under a
thick snow covering to stay warm. Without it, the small rodents are
exposed directly to cold air temperatures as they hunker down in
forests.
“Even though it’s been a warmer
winter, voles will find it more difficult (because) even if it’s -5,
they’ll feel that full -5,” the biologist says.
Another vole domino: local great
horned owls hunt voles by sound as they tunnel through the snow at
ground level. The little guys are harder to pinpoint on bare earth,
which also affects the visiting Arctic snowy owl.
Toninger says snowy owls, which have
been spotted in Tommy Thompson Park along the Leslie Street Spit, come
south now and then, probably prompted not by weather patterns but by a
low lemming count up north.
And insects? Some in this area are
highly cold-tolerant, but it’s unknown what repeated freeze-thaw cycles
might have on their survival rates and the fitness of offspring, says
Brent Sinclair, an assistant professor in the University of Waterloo’s
department of biology.
The warmer weather seems to have
tricked at least one bird that should be nibbling on juicy tropical
treats right now instead of hanging around Toronto. Toninger says a palm
warbler was spotted during a Christmas bird count he was on. It should
have flown south in September but likely figured there was enough food
and warmth here to last until spring.
“For a lot of wildlife, in an area
like this, there’s a risk-reward,” Toninger says. “If there’s enough
food to keep the fires going, they can forage at -35.”
Should there be a quick deep freeze
and the warbler decides to fly south, what happens when it burns up
precious calories as the temperature plummets?
“It probably made a bad decision and
probably will not make it,” he says, noting it would likely freeze to
death trying to fly across Lake Ontario.
FOSS members were busy this week getting the tree swallow
nesting boxes ready for the new arrivals that are already showing up - much earlier this Spring because of the
warm weather and the emergence of insects.
Preparation involves removing old, decaying nesting material, scraping
all surfaces and sterilizing with a vinegar/water solution. About three-quarters of the boxes had been
used by swallows. Some were empty, others had been claimed by song
sparrows (?) A few had been used by
overewintering wasps and field mice.
Unfortunately, two evictions of the cute interloper were necessary!
