Rideau Canal - Woodpeckers’ Secret Weapon
Woodpeckers might have the wrong name. Pecking wood is far from the most interesting thing about them.
EPISODE NOTES
TRANSCRIPT
Woodpeckers. Named for their specialized and audible hunting technique. But it turns out bashing their heads against trees for food is not even close to the weirdest thing about them.
At our first campsite on the Rideau, at Beveridge Locks, we heard an iconic sound ringing out from the trees. A woodpecker on the hunt.
It turned out to be a hairy woodpecker - I’m 90% sure. They’re almost obstinately similar to downy woodpeckers, also common in Canada. The best way to differentiate them is the size of their beak - downy beaks are slightly short and stubby, hairy beaks are slightly long and pointed. So I’m… 80% sure.
Anyway, this one was doing what woodpeckers do best: moving up and down the trees and tapping as he went. He’s checking to see if the wood is hollow. If it is, there might be insects under the bark, and he keeps hammering until he’s made a hole to get at them.
This behaviour gives woodpeckers their name. But have you ever wondered how, exactly, they do it? Because it seems there’s two pretty glaring issues here.
One, their whole plan rests on being able to bash their heads relentlessly against a solid tree trunk without giving themselves a concussion. And that is a serious concern.
Concussions happen because brains are not directly attached to skulls - they float in cerebrospinal fluid. So if we hit our heads hard and fast enough without cushioning, say against a tree, our free-floating brains can actually bash back and forth against the inside of our skulls. That’s a concussion. And woodpeckers hit trees with three times the acceleration necessary to produce a concussion - and they do it over and over and over.
That’s issue number one. Issue number two, once they’ve made a hole, they need to get at the insects inside who may be scurrying deeper into the tree.
As it turns out, woodpeckers solve both these problems with just one extraordinary organ. Their tongue. So let’s take a tour.
Starting at the tip, we can already see how unusual it is. It’s coated with especially sticky saliva and has barbs on the end to help snag insects. It’s even prehensile enough to wrap around them if it needs to.
Moving down the tongue you can see the second adaptation - there’s a lot of it. That lets them probe deep into the burrows they uncover and catch fleeing prey.
But where do they keep it all? It’s not like that tongue would fit comfortably sitting in their beak, downy or hairy. In fact, it can be twice as long as their head. This is the weirdest part of all, and an answer to how they keep from concussing themselves.
When they retract their tongue, it goes along the bottom of the beak, then up… and wraps around the back of their skull with the help of specialized hyoid bones. And that’s not just convenient storage. It provides a layer of cushioning against impacts with the tree, saving them from concussions. That’s how woodpeckers can peck wood with abandon, and get at the food inside. An unbelievable, unsung, tongue.
We named them for their most outwardly visible and audible behaviour but maybe that was premature. Instead of woodpeckers maybe they should be… I dunno. Tongue…have…ers. Right? Doesn’t that just roll off the… well, you get it.