A continuation of my previous post, “The Owl Man” on 06-10-20:
With a large population of barn owls (Tyto alba), and an occasional great horned owl, on our property in Lookout CA (Modoc County), I only have to step out my front door to find owl pellets or casts. Though birds of many species regurgitate pellets, barn owl pellets are particularly suited for study because they are large enough to be examined without the aid of a microscope. Also, since barn owls swallow their prey whole, their pellets generally contain the entire skeletons of animals making it easier to determine what the barn owl ate.
In the pictured pellet, bones can be seen without dissecting the mass. I simply broke open the pellet and two skulls were immediately visible. I certainly am not an expert, but I believe the skull pictured singly with the teeth showing is that of a vole. In the final picture a few of the other bones in the pellet are exposed. I did not do a systematic dissection of this pellet or try to reconstruct the skeleton, as is possible with barn owl pellets.
The life cycle of the clothes or wool-eating moth, except for the free-flying adult stage, takes place entirely inside owl pellets. An adult female moth lays eggs in the pellet. Once the eggs hatch the larvae (caterpillars/white grubs) eat the fur and feathers in the pellet and eventually form cocoons inside the pellet. Metamorphosis occurs and the adults leave the pellet to find mates and begin the cycle again in other owl pellets. The clothes moth along with other decomposers (bacteria, fungi, etc.) eventually break down the owl pellet and return the nutrients to the food web. Owl pellets were the original home of clothes moths before there were any clothes.
Carpet beetles also feed on the fur and feathers in owl pellets. Spiders, predators that eat clothes moths and carpet beetles, are also in and around owl pellets
Owl pellets are interesting to examine. They do not have an odor nor are they “messy”, so can be examined without any preparation. In lieu of purchasing sterilized owl pellets, wrapping them in strips of aluminum foil and heating in a 325° F oven for a half hour will kill any insects in the pellets. Alternatively, the pellets can be soaked in water containing a little disinfectant. Soaking also makes the pellets easier to break apart.
Contrary to common opinion, owl pellets are not “poo” and are fascinating to dissect.