Alcids’ balancing act: Flying above and under water
An excursion onto the high seas off our coast will offer a diverse assemblage of birds.
Some are among the most elegant flyers including two species of albatross. They soar almost effortlessly for hours on long narrow wings spanning 9 feet or more.
In the Southern Hemisphere, where there are fewer land masses to clutter the oceans, it has been discovered that some albatrosses circle the globe as they search for food even as they are raising young on some remote island. They fly by rising and falling near the ocean’s surface exploiting the variation in wind speed. Shearwaters are equally skilled.
In sharp contrast, the oceans support some of the least capable flyers, the “alcids,” a group of birds that include murres, puffins, murrelets and auklets among others. Approach a Cassin’s auklet with a boat, and it will run over the surface with flailing wings in hopes of gaining sufficient altitude to clear the next wave. Often, it simply plows through the wavetops until it is clear of the advancing boat.
It is this latter group I’d like to consider. Most swimmers have webbed feet including albatrosses, Cassin’s auklets and even flamingos. Paddling around is a time honored tradition, and it doesn’t take much energy.
When it comes to pursuing fish beneath the waves, those big, webbed feet work quite well. Loons and cormorants have little trouble securing fresh fish for dinner using just their feet to propel them through the water. I still marvel at this talent. Most fish are excellent swimmers and would seem able to stay clear of sharp beaks, but most cormorants and loons I have seen look well fed.
In a very real sense, alcids fly under water. Their webbed feet serve them when paddling around on the surface, but when pursuing dinner, they turn to their wings. The feet simply trail behind as they fly under the water.
Flying involves lift and drag, and aspect ratios among other considerations all familiar to those who design airplanes. It’s also true for those who design boats and ships, especially submarines.
Similar rules apply to flying in air and flying in water. The only difference is the degree to which density and viscosity of the medium differ.
An albatross that attempts to fly beneath the waves would be in trouble. Those marvelous long wings would be put under tremendous strain given the relatively high density and viscosity of water. Ligaments would tear, and bones would break.
No, to fly underwater wings must be much smaller and much more robustly constructed. However, those superbly adapted wings for underwater flight are rather small and overly robust for efficient aerial flight.
It’s a fine balancing act for alcids. They must fly under water to catch dinner. Then they must use the same wings to fly many miles back to the islands and cliffs where they nest.
There are better swimmers under the ocean and more talented flyers over the ocean, but alcids perform each task just well enough to thrive. There are thousands of alcids breeding along our coast.
It is a good time to visit places like False Klamath Rock, Castle Rock and Bandon to see abundant breeding common murres, pigeon guillemots and, if you are lucky, even a tufted puffin.
Stewart Janes is a retired biology professor at Southern Oregon University. He can be reached at firstname.lastname@example.org.