Owl Pellet Dissection A lab by Alexander Arcasoy

Owl Pellet Dissection A lab by: Alexander Arcasoy

About Barn Owls • Barn Owls have disk shaped faces and asymmetrically placed ears to hear well. • They can be found anywhere in the world except for Antarctica. • They eat small rodents such as voles, mice, pocket gophers, moles, and even small birds.

The Skeleton

Introduction to the Owl Lab Project The Barn Owl is an owl that can be found anywhere in the world with the exception of Antarctica. The scientific name for the barn owl is Tyto alba. Tyto refers to an owl and alba means white in Latin. The Barn owl is called the “white owl” because of the color of its face and chest. When owls eat, all of their food is sent to the gizzard where digestible parts move on and indigestible parts get produced into a pellet. A pellet contains fur and bones of the animal. A Barn owl’s pellet is not thrown up, it is regurgitated. These pellets can be found in the ecosystems where owls live in. They can make a nest in hallowed trees, outhouses, caves, wells, and large piles of leaves.

Materials • Owl Pellet • Place mat • Toothpick • Tweezers • Gloves (optional) • Scale (not shown) • Ruler (not shown) • Plastic bag (2) (not shown)

Procedure 1 st: Put on your gloves if you are using them. 2 nd: Open up your owl pellet and place on place mat. 3 rd: Weigh and measure your pellet using the scale and ruler. Record the height, weight, and width. 4 th: Start separating your pellet piece by piece using a toothpick. 5 th: Find bones in your pellet and put them in a plastic bag. 6 th: Once you have finished searching your pellet, clean any fur off of bones with tweezers and toothpick. 7 th: Put all of your fur in a plastic bag. 8 th: Look through the bones and identify them. 9 th: Place bones on an outline and glue the bones to it. 10 th: Clean up your work space.

Analysis 1. 2. 3. 4. 5. 6. 7. 8. Scientists use owl pellets to learn more about the owl by seeing how it breaks up its food. In my pellet, two animals were found. One was a pocket gopher and the other was a vole. I had gotten only 2 prey animals. Some people got up to 4 or 5 prey animals. The pellet to prey animal ratio was favorable to prey animals. This is because an owl can eat more than 1 animal per meal. In a week, an average of how many animals an owl may eat would be 2. 5 animals. In a year, an owl would roughly eat 132. 2 animals. In the 6 th grade this year, voles were the most commonly found animal in a pellet. The reason the data had many voles must have been that the barn owl likes to eat voles and there are many voles in the environment the owl lives in. This environment may be a grassy area with many tunnels so voles can escape easily.

Number of Prey Animals found in Owl Pellets Period 1 60 50 40 30 Number of Prey Animals found in Owl Pellets 20 10 0 Vole Pocket Gopher Mouse

Number of Animals in Pellet Per Student Period 1 10 9 Number of students 8 7 6 5 Number of Prey Animals Per Pellet 4 3 2 1 0 1 Prey Animal 2 Prey Animals 3 Prey Animals 4 Prey Animals 5 Prey Animals

Food Chain Barn Owl Shrew Insects Vole Mouse Grass

I learned a lot about owls from what they eat to how they digest. In my pellet I did not find all of the animals bones. This was very odd because I had found 2 animals in my pellet and that would increase the chance of having all of the bones. I also found out what owls eat. They can eat animals including voles and moles and usually eat 133 animals per year. Also, barn owls can not eat more until their pellet from their last meal is regurgitated. Since an owl can eat more than one animal per meal, some pellets have 2, 3, 4, and even 5 skeletons in them. The most commonly eaten animal was the vole based on the data that shows that there were 48 voles verses 3 pocket gophers and 10 mice. The reason may be because voles and owls live in the same area to hide from large predators. Barn owls have to hide from foxes and coyotes so a wooded forest helps them get away. Voles need to hide from barn owls so they need to live in a grassy forest that may have tunnels. Since the two animals live in the same habitat, the barn owl usually catches voles.