Kings Elementary School Owl Ecology/Owl Pellet Analysis

Today I visited the 3rd and ¾ PIE classes at Kings Elementary School in Warwick. We had a discussion on being ornithologists. It focused on how students might do a project to document where three common owls, the Eastern Screech-owl, the Great Horned Owl, the Barred Owl might be found in the Warwick area, including researching the owls’ habitat and calling behavior. This is exactly the kind of work that was done by many volunteer and professional ornithologists to complete the New York State Breeding Bird Atlas project, a multi-year project that was just culminated with the publishing of “The Second Atlas of Breeding Birds of New York State (see link below).

This discussion led to an owl pellet dissection and analysis. We can add this information to the other owl pellet analysis that I have done with other school and get an even better look at what owls - barn owls in the Pacific Northwest, northern California, Oregon and Washington – prefer to eat.

Why west coast barn owls? I do many owl ecology classes in which students take apart many owl pellets. I use many hundreds of pellets every year with all my school programs. It would be impossible for me to get enough pellets from wild owls since the pellets they regurgitate would be found spread all around the forested territories that the owls live in – a wild great horned owl, barred owl or screech-owl might spit out three or four pellets each night, but would likely do so at three or four different locations dispersed about the forest and forest edge environments that they live in. To find several pellets would be lucky, to find hundreds, nearly impossible, even if I were to find several owl nests and get the pellets expelled by the growing young. So, I buy my pellets from Pellets, Inc. (see link), which is a company located in Bellingham, WA. Pellets, Inc. collects barn owl pellets from the areas of northern California through Oregon into the state of Washington.

Why barn owls? When barn owls live in essentially open country areas of farmland or abandoned buildings (especially at the outskirts of towns) they roost and nest in barns, and old buildings like unused factories, churches or houses. After hunting and feeding upon several small prey animals the owls return to the roosting or nesting site and soon regurgitate a pellet. An owl might cough up three or four pellets a night. A family of five or six owls can produce 15 to 24 pellets a night. If someone knows where these roosting or nesting places are they can find many pellets. Pellets, Inc. hires people to visit such roosting and nesting places to collect pellets. The pellets are fumigated to kill moth larva, inspected and wrapped in aluminum foil and shipped out to scientists, teachers, students and naturalists.

Why fumigated? An owl pellet is mostly mammal fur with some bones stuffed in the package. Although the fur and bones are of no nutritional value for the owl there is still food available in the bones and fur. Some species of moth specialize in eating mammal fur – these are the very same moths that get into our closets and eat holes in our wool sweaters, suits and other clothing (after all, wool is sheep or other animal fur). Actually it is the larvae of the moths that do the eating. If a pellet has been lying around a long enough time, a female moth will find it and lay some eggs on the pellet. Larvae will hatch from the eggs and begin to eat the fur in the pellet. Pellets, Inc. fumigates the pellets to kill any moth larvae that happen to be in the pellet. You will sometimes find these dead larvae. They are small, about an eighth of an inch long, and brownish in color. If you look carefully at them you will see the segmented body, including the head and six small legs of the larva. If you find several dead larvae you will also likely find tiny black, sand-grain size specks. This is the frass or poop that the larvae produced when they were alive eating the fur. These larvae are performing the function of decomposers reducing the final remains of dead animals to their elemental parts that will then become part of the soil for plants to use in the cycle of life.

Here are the results of the Kings Elementary School owl pellet dissection:
Mr. Dinoto’s class – rodents, 17; shrews, zero; moles, zero; birds, 1 – 8 pellets dissected
Mrs. Flynn/Mrs. Nachtigal’s classes – rodents, 34; shrews, 2; moles, 1; birds, zero – 18 pellets dissected
Mrs. Parker’s class – rodents, 21; shrews, zero; moles, zero; birds, zero – 9 pellets dissected
Mrs. Kipp’s class – rodents, 20; shrews, 1; moles, zero; birds, 1 – 11 pellets dissected

Totals for all four groups
Rodents, 92; shrews, 3; moles, 1; birds, 2 – 46 pellets dissected

The average number of animals eaten per pellet was 2.1 animals.

Look at the other results for owl pellet dissections that I discuss here on the blog. You can compare these findings or, better yet, add them to the findings to get a better idea of what barn owls of the Pacific Northwest prefer to eat.