Pied-billed Grebes are small, chunky waterbirds with short necks. And this one snatched a biiiiiggg fish, about half the size of its head. That filled my head with wonder. How in the heck could this little bird — smaller than a Coot — swallow such large prey? Some research was necessary. But first, a little info.
Pied-billed Grebes are experts at vanishing underwater, where they spend a lot of their time diving for a variety of prey. That’s why All About Birds calls them “part bird, part submarine.” The menu varies, from crustaceans to frogs to insects to a variety of fishes, including carp, minnows, catfish, sculpins, killifish, sticklebacks, gizzard shad and sunfishes.
Now on to our story. The setting was Lake Washington in Seattle, where Mr. WordsandBirds and I had gone for a late-afternoon walk, looking for some brightness on a dark day:
Lake Washington, as seen from Magnuson Park, on March 6. Yes, it was dark and cold, and yes, we were feeling chilled and questioning our decision as the breeze kicked up. We forged ahead, though, and were rewarded an hour later with a bit of color (see top photo).
The top photo was our first sighting of this Pied-billed Grebe with its prey. Here, nearly half a minute later, it turns and gives us a head-on view. This seems to be a Sunfish. (Thank you, JoanNJTN.) See how wide the fish is compared with the bird’s bill and head? Impressive, right? (Time: 2:59:47.)
In just three seconds, the grebe has gained a bit of purchase on its prize. It’s 2:59:50, and there’s much work ahead.
At 3:00:47 PM, this bird has been working for nearly a minute and a half since we first saw it. You can see the bulge, but the bird’s neck isn’t very wide. The grebe turned repeatedly in the water. That made more sense after I did some reading.
3:01:20 PM: Cheeks bulging, and making good progress.
3:01:27, just seven seconds later. Here we see that the bird’s throat is bulging too.
You think we’re done? Nope. Ten seconds later, at 3:01:37, and the grebe may have lost some ground. Or perhaps the angle of the previous photos made the headway appear greater than this.
Time for a seventh-inning stretch. Pied-billed Grebes haul larger prey to the surface, as this one did. There, they use that slender but thick bill, which is powered by strong jaw muscles, to repeatedly pinch the prey until its internal organs are crushed, and death occurs. That’s the secret. So while this grebe was turning in the water, it was unobtrusively applying lethal pressure with its slender yet big-muscle-powered bill.
Now that you know how it does it, let’s get back to the action:
Once dispatched, the entrée is swallowed whole, headfirst. Ready for the down elevator (3:01:46).
3:01:49: You can see how the throat has taken on the shape of the fish. That esophagus is expanding.
Three seconds later, gulp! (3:01:52)
3:02:02: Except for the enlarged neck and up-periscope position, you might never know what was in there. Total time from when it surfaced with its prey to satisfaction was two minutes and 37 seconds.
Pied-billed Grebes have been observed removing claws from crayfish before swallowing. They have to be equally careful with sculpins, which are spiny monsters, because things can go wrong. In 1977, a Pied-billed was found dead in Arcata with about three-quarters of a dead sculpin hanging out of its bill. No evidence of piercing was found, but the sculpin’s “expanded gill covers and outward projecting preopercular spines prevented both ejection or further ingestion, causing the bird to suffocate,” said the scientist who examined the corpus, Robert A. Behrstock, Department of Fisheries, Humboldt State University. Behrstock concluded that the grebe had attempted to swallow this fish before it was adequately subdued. So, smashing the prey’s internal organs appears to be the key to success. That makes sense, as limp prey would enable the bird to position it correctly for safe consumption.
One of the Pied-billed Grebe’s more interesting quirks is that it eats its feathers. Lots of them. Because feathers have been found at its pyloric sphincter, which separates the stomach from the small intestine, they appear to help strain stomach contents, preventing passage of prey’s tough parts into the small intestine, which the grebe chucks up as pellets, according to Birds of the World. That helps explain how the grebes manage sculpin spines.
Podilymbus podiceps is the sole species remaining in its genus. It’s often alone, secretive and doesn’t flock, like some other grebes. It’s a fierce little creature, a prodigious eater known to steal food from others. This one was lucky, because another food stealer, a much larger one, floated nearby:
Common Merganser female. Fortunately for our hero, she was occupied with preening.
Gathering preening oil from her tail.
Feeling good!
And good is how I felt seeing this wonder and learning more about how this bird lives. I hope you’ve enjoyed the trip. Now let’s hear about the wonders you’ve been observing.
|
The Daily Bucket is a nature refuge. We amicably discuss animals, weather, climate, soil, plants, waters and note life’s patterns.
We invite you to note what you are seeing around you in your own part of the world, and to share your observations in the comments below.
Each note is a record that we can refer to in the future as we try to understand the phenological patterns that are quietly unwinding around us. To have the Daily Bucket in your Activity Stream, visit Backyard Science’s profile page and click on Follow.
|
