I went for a walk in Edmonton’s river valley today, at least walking was my plan, but I was quickly sidetracked by wildlife. Within minutes of arriving in the park a pack of coyotes ran in front of me. Sadly, they were a little too far and to quick for the cameras I had available. Next, I came to one of the feeding platforms set up in the park and found myself watching a downy woodpecker. Check out this Instagram post for a video.
Downy woodpeckers are one of several types of woodpeckers that live in the area. They are the smallest, coming in around 15 cm long (~6 in) and 25 g (~0.88 oz). They are easy to confuse with the hairy woodpecker which is only slightly larger and has almost identical black and white colouring. But, the downy woodpecker has a shorter beak, a few different tail spots, and a gentler call.
Of course, the one thing that all woodpeckers share is the habit of knocking on wood with their head. For most animals, humans included, banging our head against something at speeds of 7 m/s (25 km/hr or 15.7 mph) would not end well. But a woodpecker can do this repeatedly without even developing a headache. Their skulls are thicker than one might expect for their size and they have very strong neck muscles, but perhaps their most interesting adaptation is their tongue.
When they aren’t using their tongue to pull ants and other insects or insect larvae out of crevices in a tree, their extra long tongue is curled around the back of their head. As such, it has been thought to play a role in dampening the vibrations triggered by hitting wood with their beak. Jung et al (2016) studied this specialized bony tongue, or hyoid apparatus.
A woodpecker tongue has four bones in it. These bones have an unusual structure including a high degree of flexibility at the back end of the bone. Jung et al (2016) state that this unique structure needs to be further investigated to see what its exact role is in dampening impact. They also suggest that understanding this mechanism might have engineering applications. My first thought, give my sports background, is could this idea affect how we design helmets, but I’m sure the applications are almost endless.