I’ll bet you haven’t thought much about bird tongues in the last week; or maybe ever. Let me explain why they are on my mind. Last week, I was staring out the window, as I do so often in the winter months, mesmerized by the activity around our bird feeders. I watched a black-capped chickadee with a black sunflower seed in its beak. I’m sure you’ve all seen the same thing at one time or another. The little bird maneuvered the seed around and eventually dropped the two halves of the shell. The only way the bird could get at the inner seed, was by using its tongue to extract it after the outer husk was split open. Have you ever tried to do the same thing with sunflower seeds? I know professional baseball players have perfected this ability to shell the seeds using just their teeth and tongues, but every time I have tried I have ended up chewing as many shells as seeds.
Yellow-shafted Flicker tongue can retract back into its skull
From the thread thin tongues of hummingbirds, to the curled tongues of woodpeckers, to the thick and hard tongues of parrots, the diversity of tongue types is equal to the diversity of bird species. Each has a unique niche in which it finds its food, so tongues have had to evolve to match the task of food gathering. Some of the variations that have developed are magnificent and complicated.
In that category, woodpeckers and hummingbirds rank as most complicated. Both species probe deeply for their food; in tree trunks and flowers respectively. Both have developed a system whereby the tongue can be ‘stored’ inside it’s skull until it is needed. In fact, with woodpeckers much of the tongue consists of hyoid (tongue based) bones, with a fairly short, soft, flexible tip that is covered with minute barbs and sticky saliva that are effective in capturing larvae and tiny insects.
This same system is found in flickers, which are basically ground (ant) feeding woodpeckers, but they are said to have even longer tongues than their tree living relatives. Another relative – the sapsucker has a shorter, but similar system, with brushy hairs on the tip of its tongue since its food source is the sap inside the tree. Through capillary action, the high energy liquid is carried to the bird’s mouth.
With hummingbirds, their long fringe tipped tongues can be rolled to the side creating trough like tubes which collect the nectar in a flower’s deep ‘neck’. They do not suck the liquid as long thought, but also use a capillary technique and as the tongue is retracted, the nectar is swallowed in the normal way. If you attach a hummingbird feeder with a suction cup to a window, you can watch these delicate little gems and you just might see the thread like tongue poke out on occasion. They are the only birds I have ever seen ‘stick out their tongue’.
Most songbirds have tongues that can reach out only the length of their bills. While we use our tongues to help form our words, it is not believed that bird tongues play a role in their singing, though the tongue can be seen to move at these times. The same is true of the so called ‘talking’ birds – the parrots, parakeets, and crows. Someday, a researcher may figure out a way to study this phenomenon better.
The robin’s tongue is slightly split at the tip and at the rear has a row of backward facing fleshy spines. Their purpose seems to be to direct food back towards the throat. I learned about this type of tongue while banding some years ago. A robin had struggled while in the fine mesh net and had gotten one of the threads in its mouth. It took several stressful minutes (for both the bird and I) to unhook that bit of thread. It was an experience I hoped not to have again, but if you band enough birds, it will happen again. It is surprising though, considering how many birds I have banded, how few tongues I have seen in the process.
The Robin’s stiff tongue is forked. Photo credit: Laura Erickson
As I was writing this column, I found myself moving my own tongue around and marveling at its many uses. We humans are fortunate that way, but one thing I bet none of us will ever see is a bird with its tongue stuck to a metal flag pole. Makes you wonder which is the smarter species.
By Kate Crowley