Studying owl pellets is a fun and interesting way to learn about owls. Owls are amazing birds that are well adapted to their nocturnal lifestyle. While spotting owls in the wild can sometimes be a challenge, looking for pellets can be a rewarding way to get to know the owls in your area. By dissecting the pellets you can learn about the prey animals that the owl fed upon.
Owls are raptors, or birds of prey. Their physical and behavioral adaptations allow them to be very efficient night time hunters. All owls are in the family Strididae , except the Barn Owl, which belongs to the Tytonidae family. Owls have amazing vision, much better than humans that enable them to spot small prey from far away. Owls' eyes are large to allow more light in. While humans can move their eyeballs to see, owls must more their heads. It may appear that owls can spin their heads all the way around, but in fact they are able to rotate about 270 degrees. Many birds have eyes on the sides of their heads and can only use one eye at a time, but owls like other predators, including humans, have forward facing eyes. This binocular vision allows for depth perception.
As hunters, owls also rely on their acute sense of hearing. Many owls have feathers configured in large facial disks that help channel sounds to their ears. The ears are slightly offset, so the owl can pinpoint the location the sound is coming from. The feathers at the tips of the wings are soft and fine, so as to eliminate any flapping sound. As they fly owls can silently sneak up on prey as well as be able to continue to hear the prey moving. The owl can then grab the prey with strong sharp talons and carry it back to a perch to eat.
Owls are carnivorous, devouring small mammals, amphibians, and insects. Owls do not chew their food, but rather swallow the prey whole. The soft fleshy parts are digested, but the bones, fur, insect exoskeletons and other hard materials are retained in the gizzard. This material is formed into a ball and then regurgitated as a pellet out of the owl's mouth. Mice, voles, rats and other small mammals are typical owl fare. Large owls, such as the Great Horned Owl can even eat rabbits and skunks. The smaller owls, like the Flammulated Owl eat mostly insects.
Identifying owl species by the pellet they make can be tricky. Some owls make distinct pellets, such as barn owls' which are very compact and dark. Typically though, pellet size, texture and color can vary depending on what the owl is eating. In general larger owl species are going to produce larger pellets and smaller owls, smaller pellets. Habitat association can be a useful way to start learning to identify the species.
Owls typically roost in the same place. Looking for white droppings at the base of a tree can be a good indication of owl habitation. If an owl has been using that roost for awhile there may be quite a few pellets on the ground. If you find these signs you may have a good chance to see the actual owl if you are patient. Conversely if you have spotted an owl roosting on a branch, searching the ground around the tree will most likely yield pellets. A good bird field guide will help you limit your owl ID by location, habitat, call and visual appearance. If you have the pellet than you have the additional information about what and how much the owl is eating.
While it is rewarding to go out and find the owl pellets in the wild, if this is not feasible you can order pellets from biological supply companies. These pellets will come sterilized. If you have collected your own it is a good idea to sterilize them before handling them. To do this, wrap them in aluminum foil and heat sterilize them by baking at 325 degrees for 30 minutes. Pellets should be dissected on a surface that is not used for eating or cooking and hands and tools should be washed with soap afterward. These precautions are important for safety, but also for teaching good scientific lab practices.
To dissect an owl pellet, use tweezers and a dissecting needle to carefully separate the bones from the soft fur. Small mammal skulls and jaw bones will have teeth, bird skulls will have a beak, insect remains will be an exoskeleton that is softer than bone. Small mammals will be the most common prey for many owl species, such as barn owls. Mammals can be identified by their skull and jaw bones. Bone charts for identifying common prey animals will often come with purchased owl pellet dissecting kits or can be found online. If the bones are fairly intact you can reconstruct the skeleton. It's amazing to get such a clear hands-on view of what the owl fed upon.
Owl pellet dissection is a great opportunity to teach several biology and ecology concepts in a fun hands-on way. It is an ideal activity for families as well as a good classroom lesson. If there is the option for exploring the roost site and collecting the pellets a more in depth lesson is possible.
A typical lesson plan could include a discussion of owl adaptations. Students can brain storm why owls have the features they do or conversely ask students to think about what body parts and behavior would be needed to hunt at night. Discuss how owls hunt, feed and how the pellet is made and left behind. During the dissection help students find the skull and other bones within the pellet. Help students to identify what prey animal remains are in the pellets. If the students collected the pellets, they could return to the area and look for signs of the prey animals they identified, such as scat, tracks or nests. Conclude with a review of owl adaptations, what role they play in the ecosystem, and what ornithologists can learn from looking at pellets. Owl pellets provide a great opportunity to explore the natural world and gain insight into the amazing world of owls.
