Ever wondered what owl pellets are? this article talks about what they are and what important things they can tell us about the owls that produced them.
by Maia Tañedo
We go out and look for owls and we automatically look upwards at the trees. The recent sightings of the Philippine Eagle Owls in two separate locations in urban areas in Luzon, as well as a family of Philippine Scops Owls, taught me not only to look up at them but also to look down: down at the areas under their perch to look for pellets.
Owls are one of the many species of birds who regurgitate the indigestible parts of their prey in the form of pellets. Often, owls will swallow their prey whole. If the prey happens to be too large, the owl rips it apart using its strong, hooked beak and swallows its prey in chunks. In their digestive system, the soft, digestible parts are pushed through the digestive system while the hard, indigestible parts, like bones, fur and hair, are compacted in the bird’s gizzard to form a pellet. Later on, approximately 10-16 hours after ingestion, the owl regurgitates the pellet. We then find these pellets below the bird’s roosting place as balls of hair or fur (sometimes even feathers!) and bones.
Studying owl pellets can provide information about the feeding behavior of that specific owl. It may provide information about the diet, food preference, and hunting behavior of the bird. At present, there is limited data about the behavior of the Philippine Eagle Owl (Bubo philippensis.) The recent sightings now allow for more opportunities to observe and document their behavior, breeding information and feeding patterns. Observations from the two families of Philippine Eagle Owls are consistent and may be useful information about their species.
When I first saw the family of Philippine Eagle Owls in Quezon City, I focused entirely on the birds. I admit I was curious about the white splashes of owl droppings on the road under its perch and even took a photo of it. At that point, I was not even aware that owls regurgitated pellets! Not until Desmond Allen commented that someone should start collecting and examining the pellets.
I saw an opportunity to see, examine and possibly collect some pellets when we went to see the Philippine Eagle Owls in Angono. After looking up at the majestic adult owl, I turned my attention to the area exactly below its perch. At first, I did not know what to look for. I imagined balls of fur with bones sticking out. And that’s pretty close to what I saw. On the steps below the owl’s perch, I saw clumps of gray hair with bones scattered in it. Suddenly, there were bones everywhere! I could now see so many clusters of broken bones on the floor. I collected a few samples to bring home and hopefully identify.
Gathering information from other birders who have went to observe the Philippine Eagle Owl and inspected some pellets, all observations have been consistent so far. The pellets found in the site were made of loose materials, usually fur and bones, and are found as scattered pieces on the ground.
I recently found a pellet from a site where Philippine Scops Owls were seen. In contrast to the Philippine Eagle Owl pellets, this pellet was smaller and compact. It was round and the contents were tightly packed. It was much more difficult extracting the tiny bones inside the pellet.
I am in the process of getting expert help in identifying the exact species of rodents and amphibians whose bones I was able to collect from the Philippine Eagle Owl. This information can help us determine, not only the diet of the owls, but their feeding behavior as well. If the rodent bones are identified to belong to a species which is active during the day, then that can tell us that the Philippine Eagle Owls hunt during day time. However, if the species of rodents are nocturnal, then that would tell us that the owl’s are hunting at night. Interesting right? So next time you see an owl, try searching for their pellets too. It’s a very interesting way of understanding the feeding behavior of owls.
Here are some bones collected from the Philippine Eagle Owl: