Frozen frogs, a butt-breather and a seasonal genius: How Ontario wildlife survive the winter | 24CA News
CBC’s Great Lakes Climate Change Project is a joint initiative between CBC’s Ontario stations to discover local weather change from a provincial lens. Darius Mahdavi, a scientist with a level in conservation biology and immunology and a minor in environmental biology from the University of Toronto, explains how points associated to local weather change have an effect on folks throughout the province and explores options, particularly in smaller cities and communities.
Surviving a Canadian winter generally is a wrestle — even with trendy heating. But Ontario wildlife have been enduring the chilly for hundreds of years.
Monarchs and hummingbirds migrate hundreds of kilometres, and bats and bears hibernate for months. But there are additionally animals that survive the winter in your personal yard, in methods you would not anticipate.
Here are a few of them.
Frozen wooden frogs
If you are keen on winter walks by means of forests in Ontario — and certainly most of Canada — odds are you’ve got tread on a frozen frog.
Meet the wooden frog. You’ve in all probability seen wooden frogs in the summertime, when they’re a standard sight throughout the nation.
But when winter rolls round they disguise underneath leaf litter or only a few centimetres underground, the place the temperature hovers a couple of levels under zero.
And then they freeze.
Their hearts cease pumping, their organs cease working. They do not breathe and haven’t any detectable mind exercise. Their physique is encased in ice. You’d assume they have been useless.
But then comes spring, and so they begin to thaw — from the within out.
“They’re alive. Then they get dead during the winter — their life force seems to be going, and then they come back to life,” mentioned Ken Storey, a professor of biochemistry at Carleton University In Ottawa who has carried out intensive analysis on the wooden frog.
WATCH | Check out this documentary on wooden frogs from The Nature of Things:
These wooden frogs are one of many solely creatures that may be described as “the living dead”. Yet each spring they arrive again to life once more.
Freezing each winter looks like an unattainable life historical past — and for many animals it could be.
“Pure water freezes out [of the blood] as ice, leaving behind really concentrated blood, [which] tries to balance itself by sucking the water out of your cells,” Storey mentioned. This begins a cycle the place water retains being pulled out of cells solely to freeze, requiring extra water to be drawn out.
“Your cells actually die. You die of freezing by shrinking the cells down,” Storey mentioned. Similar to a deflating balloon, if an excessive amount of water leaves the cell, the membrane begins to break down inward.
But evolution has given wooden frogs a approach round this.
It’s all about preparation, Storey mentioned. So wooden frogs spend the autumn build up power reserves.
When temperatures drop to freezing, their organs begin to shut down whereas the liver will get to work changing these shops into glucose. As a end result, an overwintering wooden frog’s blood has 80 instances extra sugar in it than the common human’s.
“That’s an antifreeze,” Storey mentioned. “You can’t freeze glucose. They have way less ice than you would think at any given temperature because they have so much sugar.”
The sugar lowers the freezing level of the water within the blood and organs, and reduces the quantity of water drawn out of the frog’s cells, Storey defined.
As a end result, as much as 70 per cent of the extracellular water in an overwintering wooden frog can freeze with out ice forming inside cells, leaving no hint of harm after they thaw in spring.
Butt-breathing turtles
Ontario is residence to eight freshwater turtle species. Six of these species could be discovered at Point Pelee National Park, together with the endangered Blanding’s turtle and spiny softshell turtle, mentioned Julie Charlton, the useful resource conservation supervisor at Point Pelee in Essex County in southwestern Ontario.
Ontario’s turtles spend the winter in frozen-over ponds, unable to floor for air, Charlton mentioned.
Instead, they take in oxygen from the water by means of a number of surfaces, together with the cloaca — a specialised tissue positioned underneath their tails. This course of is named cloacal respiration.
But there’s additionally a much less scientific solution to describe it, she added.
“Essentially, in the winter time, they are breathing through their butts.”
The final multi-tool, a turtle’s cloaca has many capabilities, together with excretion, urination, copy, egg laying and — in a pinch — oxygen uptake.
Ontario’s grownup turtles aren’t freeze-tolerant like a wooden frog, and might’t regulate their physique temperature like birds or mammals. Instead, they should discover a place to spend the winter the place temperatures will not drop under freezing.
So they hunker down on the backside of frozen-over ponds and lakes, the place the water stays simply above zero.
“[Turtles are] ectotherms — I think most folks will say cold blooded — [so they] allow their body temperature to drop to almost zero degrees Celsius while they’re sitting in their cozy little mud spot,” mentioned Charlton.
“Their entire metabolism slows down. They actually decrease their heart rate to one beat every 10 minutes.”
This is named brumation. It’s primarily the reptile and amphibian equal of hibernation, although if you happen to’re fortunate, you possibly can nonetheless generally see turtles swimming round beneath the ice.
Without entry to the floor, turtles’ lungs aren’t a lot use. But they do not have gills and might’t take in sufficient oxygen by means of their pores and skin like frogs do.
So they get the little oxygen they want by means of specialised surfaces like their cloaca, which has extremely concentrated blood vessels that trade gases with the water and carry them all through the turtle.
Since there may be much less oxygen in a turtle’s blood than within the water, oxygen enters the blood. The reverse is true of carbon dioxide — concentrations are greater within the blood, so it exits into the pond. This passive gasoline trade, referred to as diffusion, occurs with out the turtle needing to do something.
So if we’re versatile with terminology, we are able to certainly say that when turtles take up oxygen by means of their cloaca, they’re respiration by means of their butts.
Chickadees: Seasonal geniuses
While many birds head south for the winter, the black-capped chickadee braves the Canadian chilly.
Common throughout Ontario, you may not assume a lot of those little birds — however their pea-sized brains would possibly shock you.
“Chickadees are scatter hoarders. So they store individual food items in dozens of different locations and then they retrieve those,” says Scott MacDougall-Shackleton, a professor of psychology at Western University and director of the Advanced Facility for Avian Research in London, Ont.
“A few hours later, or a few days later or sometimes even longer and they need to use spatial memory to retrieve those stored food items.”
Though they disguise and retrieve seeds 12 months spherical, remembering the placement of these stashes is very essential within the winter, when meals is scarce. The answer? Make that a part of the mind greater.
“There’s a brain region called the hippocampus, which is critically important for spatial memory,” mentioned MacDougall-Shackleton. “At the time of year when they most need to use their spatial memory is the time that the hippocampus is largest.”
Leading as much as winter, the chickadee hippocampus can develop as a lot as 30 per cent. But that is not the one approach their mind adjustments all year long.
“In the springtime, the regions that control their singing behaviour get new neurons and get larger … almost double in size,” MacDougall-Shackleton mentioned, explaining this possible helps them entice mates throughout breeding season.
But most birds, together with black-capped chickadees, have quite a lot of different diversifications that additionally assist them survive the winter, defined MacDougall-Shackleton.
These embrace:
- Behavioural adjustments, like huddling collectively to sleep.
- Seasonal acclimations, like rising further layers of down feathers.
- Evolutionary diversifications, like regulated hypothermia and a specifically tailored circulatory system.
This circulatory system, referred to as countercurrent warmth trade, includes pairing arteries carrying heat blood from the animal’s core with veins carrying chilly blood from the extremities, particularly the ft. This approach, the warmth transfers into the blood heading again to the guts and fewer warmth is misplaced to the setting.
This has independently developed in lots of animals, together with mammals like coyotes and wolves. In truth, the entire diversifications mentioned right here developed a number of instances, generally in very completely different species — a course of referred to as convergent evolution.
After all, there are lots of methods to outlive a Canadian winter, many greater than we have coated right here. But when one thing works effectively, evolution tends to deliver many species to that identical answer.
