Ever eat an insect and notice how hard the outer shell, or exoskeleton, is?
I hope you answered no to that question. I certainly haven’t. But you can imagine that if you ever did bite into an insect it would be crunchy, kind of like eating a lobster without removing the meat from the shell first. You can also imagine that the exoskeleton would be difficult, if not impossible, to digest.
So how does that undigested shell come out? Everyone knows that owls regurgitate pellets of undigestible material, such as beaks, bones, feathers, claws and fur. Not as commonly known, however, is that many insectivores (things that eat insects) regurgitate pellets as well.
I was aware of this, but never witnessed it until the other day when I was watching an Eastern Kingbird. It was perched in a small tree at Cove Island Wildlife Sanctuary in Stamford, Conn. I was photographing it anyway when suddenly it opened its bill wide and started shaking its head. Finally what looked to me like a black superball came out of its throat, passed through the open bill and fell to the ground. Not a behavior you see every day.
A kingbird’s diet is comprised mainly of insects, but also includes some fruits. Some of the fruits contain seeds that are expelled in a similar manner. But the pellets are mainly made up of insect exoskeletons. Imagine eating a grasshopper or locust. There’s good juicy stuff inside there, but without being able to use a shell cracker, you also have to eat all the wings, legs and shells that come with the insect.
It may not sound appealing, but I wish I had tried to find the pellet. It would have been interesting to see what the bird had been eating — if anything would have been discernible. Biologists study pellets in that manner, which gives insight into birds’ diet and behavior without actually harming the bird itself.
So we know that owls and kingbirds expel pellets. But the list hardly ends there. In fact birds of prey, shorebirds, herons, gulls and many songbirds do as well. On your next walk outdoors, keep an eye out for pellets or birds expelling them. There’s always something to learn from our birds.
(A final note: The quality of the photos, I admit, are somewhat lacking. My lens is not working properly and I haven’t gotten around to sending it ‘back to the shop’ yet. Just throwing that out there … Thanks for checking in with BirdsofNewEngland.com)
Now here’s a sequence of photos: