Owl Pellet Lab Student Data Sheet printable pdf download

DO NOT WRITE ON THE INSTRUCTION SHEET

Owl Pellet Lab Instructions

Owls catch their prey, which include small birds and rodents, and swallow them whole.

Enzymatic juices break down the body tissues of the prey but leave the bony materials and

hair or feathers undigested. Depending on the prey eaten the undigested portions may include

beaks, masses of bone, teeth, hair, feathers and exoskeletons of various animals preyed upon

by raptors, or birds of prey. Unlike snakes, the protein enzymes and strong acids, which occur

in the digestive tract of raptors, do not digest the entire meal. The relatively weak stomach

muscles of the bird form the undigested fur, bones, feathers etc. into wet slimy pellets. In this

process even the most fragile bones are usually regurgitated, preserved unbroken. Pellets are

produced and regurgitated not only by owls but also, by hawks, eagles and other raptors that

swallow their prey whole instead of in small pieces. Owls feed early in the evening and

regurgitate a single pellet approximately 20 hours after eating.

Scientists take advantage of this adaptation by collecting these pellets. Owl pellets are

dried and fumigated so that their contents can be examined. Since owls are not selective

feeders, pellets can be used to estimate the diversity of available prey. The contents are also a

direct indicator of what an owl has fed on – information that is crucial for species management

and protection.

Materials

• Owl pellets

• Dissecting Needle/toothpicks & tweezers

• Ruler

• Dissecting Tray

• Dichotomous key supplemental handout

• Bone chart handout

Dissecting an Owl Pellet - Procedure

1. Carefully unwrap your pellet and place it on you dissecting tray. Measure the length and

width of your owl pellets. Record this information on your data sheet.

2. Carefully examine the exterior of the pellet. Do you see any signs of fur or feathers? Describe

the pellet? Record your observations your data sheet.

3. Carefully use a toothpick to break apart the owl pellet and observe what is within. Be careful

to avoid damaging small bones while you pull apart the pellet. Use a toothpick to expose all

bones for identification. You may want to arrange the bones on a sheet of paper. Use the

bone diagram to help you identify your bones and complete the chart on the next page.

4. Count the number of skulls to determine the number of prey in the pellet? Record on your

Data sheet.

Owl Pellet Lab Student Data Sheet