Mystery Leftovers
Arthur spotted something on the railing as we were walking along the boardwalk at Lake Ashby the other day. “What’s that red thing?”
Click on any of the photos to embiggen via Flickr.
A pellet, that’s what! I wanted a closer look so I picked up a stick and went back to the pellet for a little dissection. It was reddish-orange. It looked like there was some shell or exoskeletal-type material. And crab legs?
There were two tiny round white shells. At first it seemed like the bulk of the red-orange stuff was plant-based, but as I sifted through it seemed more like it all consisted of crustacean exoskeleton. That makes sense… plant stuff would more likely just pass on through, I suppose. There were quite a few tiny crab legs.
I wish I had taken a photo with a coin or something to show scale. I guess the intact pellet was about 5cm long.
The pellet was in a very exposed area, on boardwalk railing over Lake Ashby. I took this picture after opening up the pellet — see the reddish area on the railing?
Here’s another view of the boardwalk at Lake Ashby.
So my big question is: what bird cast this pellet? I had a few guesses so I looked up some species accounts on Cornell’s Birds of North America Online (BNA). In many species, information regarding pellet-casting is not mentioned or it is acknowledged as being unknown. What would eat a bunch of crabs and then hang out on an exposed boardwalk railing long enough to produce a pellet?
After checking the species accounts of several duck species (not much data or no pellet-casting), various water birds (Double-crested Cormorants tend to cast pellets at roosting sites), and a bunch of waders (Great Blue Heron pellets tend to have hair in them; Tricolored Herons eat mostly fish; etc), the pellet-casting data of the White Ibis kind of jumped out at me: Non-digestible hard parts, such as fish bones, arthropod exoskeletons, and crayfish gastroliths are cast in pellets.. Did someone say crayfish gastroliths? That’s what those little white “shells” in the pellet appear to be. I can’t be sure, but White Ibis seems to be good candidate. We saw a few Little Blue Herons during our walk, so that species was my first guess, and I still think that is also a likely candidate. Both species of Night-Heron are also possible. I would love to hear suggestions from anyone else, though. Have you ever found a pellet like this one? Do you know who cast it?
