Abstract

Objective

The goal of this science project is to identify the types of prey that are consumed by owls by examining the contents of owl pellets.

Introduction

Click here to watch a video that you will "dig", produced by DragonflyTV and presented by pbskidsgo.org.

Have you ever wanted to dig up your own fossils and figure out what they can tell you about the creatures that lived long ago? Ashley and Brandy from DragonflyTV got a chance to do just that! For their science project, they went out to an archeological dig site in Texas and excavated for microfossils. Microfossils include teeth, jawbones, and other tiny bones. Ashley and Brandy wanted to find out what other animals lived alongside the big dinosaurs in Texas. What do you think they discovered? Watch the video to find out!

It can be pretty hard to get an invitation to dig at an actual archaeological site. But don’t let that deter you—you can still practice your bone identification and skeleton reconstruction skills using an owl pellet. When owls eat their prey, they swallow large pieces that they have torn off with their beaks. They don't have teeth to chew, so these pieces pass into the owl's gizzard, where they are processed into smaller pieces. Small, sharp bones would damage an owl's digestive system if they passed through it, so the gizzard retains the bones. The bones and fur are later coughed up from their gizzard in the form of a pellet.

You can sometimes find owl pellets in the woods. The size and shape of the pellet varies with the species of owl, and with the prey. Most are oval in shape, but can vary in size. Some pellets are furry. Barn owl pellets tend to be compact and dark. Figure 1 shows a picture of an owl pellet, alongside the bones that were later dissected from it. You can find additional pictures of pellets in the resources listed in the Bibliography, and you can easily find more with an online search.

Figure 1. An owl pellet (right) alongside the bones that were later dissected from it. (Math Science Nucleus, 1998.)

If it is not possible to collect your own owl pellets, they are available for purchase online, from multiple sources. Note that many of the pellets available for purchase have been heat-sterilized for your convenience.

By carefully teasing apart the pellet, you can separate the bones from the fur, and reconstruct the skeleton of the prey animal that was eaten by the owl. Can you identify the animal from its skeleton?

Terms, Concepts, and Questions to Start Background Research

To do this science project, you should do research that enables you to understand the following terms and concepts:

• Owl pellets
• Gizzard

Bibliography

• TPT. (2006). Dinosaurs by Ashley and Brandy. DragonflyTV, Twin Cities Public Television. Retrieved May 13, 2008 from http://pbskids.org/dragonflytv/show/dinosaurs.html
• This is a great page to visit before starting on dissecting your real owl pellet. You can get a feel for how to do the real dissection by trying the virtual experiments on this site. It also has lots of great background information:
  Hildreth, J. (2004). Virtual Owl Pellet Dissection. Retrieved December 28, 2006 from http://www.kidwings.com/owlpellets/index.htm
• This webpage from Carolina Biological has rodent bone charts available for download:
  Carolina Biological Supply. (2005). Bone Chart. Retrieved May 16, 2008 from http://www.carolina.com/category/teacher+resources/classroom+activities/owl+pellet+dissection+bone+chart.do
• Here is another site with information about owl pellets:
  Math Science Nucleus. (1998). Exploring Owl Pellets. Retrieved January 22, 2007 from http://www.msnucleus.org/membership/html/k-6/lc/ntenvn/2/lcne2_5a.html

Materials and Equipment

To do this science project, you will need the following materials and equipment:

• Owl pellets (heat-sterilized); available from Carolina Biological Supply Company (and other sources):
  • Individual study kit (e.g. catalog number 22-7801), or
  • Regional variation study kit (catalog number 22-7850)
• Clean paper for working on
• Forceps or needles
• Small bowls or several sheets of paper
• Magnifying lens
• Owl pellet bone chart; available for download from Carolina Biological http://www.carolina.com/category/teacher+resources/classroom+activities/owl+pellet+dissection+bone+chart.do.

Experimental Procedure

1. Follow the procedure shown in the Virtual Owl Pellet dissections (Hildreth, 2004). Briefly, the steps are as follows:
   1. Unwrap the owl pellet and place it on a clean sheet of white paper.
   2. Using forceps, or needles, gently tease the pellet apart into four quarters.
   3. Next, tease each of the quarters into two pieces.
   4. Separate and discard the bits of fur.
2. Using a bone chart as a guide, identify and sort each of the bones (or bone fragments) from the pellet into bowls or on sheets of clean paper.
3. What distinguishing features can you use to identify the skeleton? Use your magnifying lens to check them out closely.
4. Finally, remember to wash your hands when you are done!

Variations

• Use the regional variation owl pellet study kit to find out what animals are prevalent in the diet of owls from different parts of the country.
• If you live near a wooded area, perhaps you can find owl pellets on your own. Find out what the prevalent prey animals for owls in your area are. We recommend wrapping the pellets in aluminum foil and heat-sterilizing them at 300°F for 30 minutes before dissecting them. Allow the pellets to cool to room temperature before dissecting. As always, wash your hands after handling the pellets, even after sterilization.

• For more science project ideas in this area of science, see Geology Project Ideas.

Credits

Andrew Olson, PhD, Science Buddies

Sources

This project is based on information from:

• Carolina Biological Supply. (2005). The Secret Lives of Owls/ Retrieved December 28, 2006 from http://www.carolina.com/owls/index.asp, and
• Hildreth, J. (2004). Virtual Owl Pellet Dissection. Retrieved December 28, 2006 from http://www.kidwings.com/owlpellets/index.htm

Last edit date: 2008-06-18 16:10:00