Rideau Canal - Are Walnuts Worth It?
A strange sound at Poonamalie Lockstation leads to the fascinating (and sometimes surprisingly Canadian) dietary habits of one industrious rodent.
EPISODE NOTES
TRANSCRIPT
At our last campsite on the Rideau, at Poonamalie lockstation, I kept hearing a weird sound coming from the trees. It was a soft but persistent… scraping. And it felt like it was going on forever.
For the life of me I could not place it, so I decided to go investigate and came upon: a red squirrel, who was working tirelessly to get into a walnut.
Now walnuts are a tough nut to crack even for us. In 2019, scientists actually discovered that they’re built of a single, unique, previously unknown type of cell that makes them so strong - because each of those cells interlocks with 14 neighbouring cells. That’s why walnuts take around 73 pounds of pressure to crack. Or, if you’re a squirrel, a marathon of gnawing.
But its worth it to them, for two reasons. First, nuts are really nutrient and calorie-rich, so the extra time it takes to get to them pays off. And second, the effort of getting through the shell is, itself, beneficial. Squirrels, like all rodents, have teeth that never stop growing. They need ways of wearing them down - like this.
And you can actually tell from discarded walnut shells who’s been eating them. Each species has their own technique. Grey squirrels, for example, work on the seam until it weakens enough to open the walnut. Red squirrels prefer to chew holes into each side separately.
It may take them a little while - an average of ten minutes of gnawing - but the squirrels have their technique down.
And red squirrels have evolved another smart - and incidentally Canadian - dietary trick. They tap maple trees by scraping their teeth along the bark.
But that’s not even the best part. What comes out of the tree at that point is a watery - and not very calorie-dense - sap. So they’ve learned to leave it for a day and return when the water has evaporated and the sap has concentrated. If that basic technique sounds familiar, it’s because, yes, these squirrels are effectively making themselves maple syrup.