by Bob Thomas
One of the really neat factors about nature is the element of surprise and discovery, no matter how long you have indulged your curiosity.
I made my first jaunt to the beach in Galveston, Texas, about 62 years ago. Well, not exactly a jaunt, but more like being carried in my parents’ arms. We lived in central Texas then, but the beautiful coastal Gulf of Mexico beaches were just a short drive away. I was hooked. The infection became more intense when I fished all night with Granddad Schneider and his friend, Larkin.
Marrying a girl who loved beaches as much as I solidified the addiction, and this was followed by infecting each of our children with the same bug.
Bottom-line, as a naturalist I’ve visited beaches often, and on all continents.
In November, 2010 my Loyola delta ecology students and I were sauntering down the Grand Isle beach when I found a curious aggregate of small coquina clam (Donax variabilis) shells and very tiny examples of other local mollusk species. On hands and knees, I could see that it wasn’t always a pile, but usually a somewhat fused mass. In fact, the shells were distributed all along the beach wrack, the debris washed up by waves on the face of the beach.
What is this? I’ve never seen this in all my sojourns along Gulf coast beaches.
We were near the middle of the town’s stretch of beach and had just come from the state park at the eastern end of the barrier island. We saw few birds, but I had commented to the students about willets being the dominant visitor that day.
There were no willets in sight where I found the shell packets, but they were seen moving along the beach earlier and later. There was also evidence that a bird in that size range (beak size) had worked the edge of the beach, presumably poking around in the sand at a higher tide level.
The shell pellets had no odor, suggesting that they had been regurgitated, much like owl and hawk pellets, rather than having passed through the digestive system.
As is normal, I sent photos to a few regional bird experts (David Muth, Dan Purrington, Bill Fontenot, James Beck), but none had observed the pellets in the field.
Until we get direct observations, we’ll go with the willet as the source. They typically move up and down beaches probing sand in the swash zone consuming whatever their beaks encounter. In this case, the immature coquina and other small clams must have been abundant, so to get the nutritional value they needed the willets had to consume huge quantities. Being so small, the size of the coquina bodies was tiny, so each bird had to consume huge numbers.
The result was tightly packed empty shells being “erped” up to make room for more.
A quite fun observation.
A pellet of shells found in the beach wrack A typical shell pellet observed on the
at Grand Isle, Louisiana, in November, 2010. beach. It was about 1.5 inches long and
Photo by Bob Thomas. 2/3 inch in diameter.
Photo by Bob Thomas.
Some of the shell pellets separated A willet feeding along a Gulf of Mexico
when they dropped to the beach. beach.
Photo by Bob Thomas. Photo by James Beck.