The seasons may be shifting, but early spring isn't always a good thing
Can have devastating effect on pollinators, other key species, say scientists
The seasons are shifting.
Summers last longer, autumn creeps in later, winters are short and hard, and spring seems to come earlier each year.
While some of us delight in a warm March and thrill at crocuses poking through the soil, scientists point out that an early spring can be terrible for ecosystems. If a flower blooms before a specific pollinator emerges — well, that's not a good thing.
Climate change scientists study seasonal shifts over long time periods, examine data on blooms, buds, flowers, migratory birds and butterflies to determine whether the seasons are actually shifting.
"We examine trends over time, and from this research, we can definitively say that indicators of spring come earlier in Newfoundland and Labrador than it used to. We still have a strong oceanic influence, so we see less pronounced seasonal shifts than in other places, but it's happening here," said Shawn Leroux, a biologist at Memorial University in St. John's.
He said earlier springs can have severe consequences for local ecosystems.
"Scientists call this a phenological mismatch. It's an imbalance between when a food source is ready and when the creature that depends on that food source is around. Earlier springs mean that these creatures that depend on each other may not be active simultaneously," he said.
Leroux points to March 2011 as an example of a phenological mismatch.
"That year Eastern Canada had a week or two of warm weather in March. High winds carried millions of red admiral butterflies to the area. Suddenly, our temperatures dropped below zero, and most of these butterflies likely died," he said.
When a major pollinator has a mass die-off, the consequences aren't small. In March 2011, it's likely there were fewer flowers, fewer plants reproduced, and predators who depend on the red admiral butterfly probably struggled to find food.
Leroux said some species can adapt to seasonal shifting.
"There are winners and losers. Some species will move. A mobile species can change their habitat. They can look further for food, others species will adapt and find new food sources, but some species will die," he said.
But pollinators, Leroux said, are incredibly fragile.
"I think we need to worry about them. Bees and butterflies, insects that regulate their body temperatures based on their environment, may not be able to adapt to shifts in temperature as well as mammals. I also worry about birds that have a single food source. A robin is a generalist, but some birds consume very specific things, and if it's not available those species may need to move or perish."
Snowshoe hares could be in trouble
The snowshoe hare is another species feeling earlier springs.
Micheal Peers, a postdoctoral researcher at Memorial University, has spent years living trapping, measuring, and recording data on hare populations. His research suggests the hare may be in trouble.
Since hares have evolved to change their coat from brown to white in winter for camouflage, an early spring means white hares pop against the brown ground, looking like discarded milk jugs in the forest.
"They are mismatched against their backgrounds, so predators can easily spot them. It could lower their survival rates and cause localized extinctions in the southern regions of their range," he said.
Meanwhile, the hare faces another climate change-related challenge.
Snow depth — which gives hares an edge over predators — has decreased by about 33 per cent in less than 20 years.
"Snowshoe hares have huge feet, which help them run in the deep soft snow. With more rain in winter, we get shallower, harder snow, which means they lose their advantage — especially to coyotes. Their populations will probably decline," said Peers.
Hares are what's called a keystone species in the boreal forest, meaning other species depend on their continued survival.
"They naturally go through population cycles, where numbers rise and fall fairly predictably every decade. In the peak, there can be as many as 150 in a square kilometre, wherein the low there can be less than five in the same place," Peers said. "These huge changes in numbers cause predators like lynx, coyote, great horned owls and others to rise and fall with the hares. So if hare numbers crash, many other species will be affected."
Scientists and citizens are asked to imagine possible climate change-related future scenarios and solutions, but seasonal shifting and phenological mismatches are happening in the present.
So what can people do? Leroux has some ideas.
"Planting a garden with flowers that bloom at different times of the year is a step people can take. A garden that contains native species but is also diverse is a great way to help out some of our most fragile pollinators. Citizen science is a helpful way to take action. If you see a bird early or a butterfly, log that data with [online databases] eBird or eButterfly. That data is really useful," he said.
Outside individual actions, Leroux believes in organizing.
"This is a problem to solve collectively. We need to hold elected officials responsible. Vote for people who plan to reduce the effects of climate change. Climate change is not fiction. It is happening, and we'll have the same choices as other animals: move, adapt or die."