Owl Pellet Dissection
Knowledge Questions:
1. Owl pellets have been used for scientific study of small mammals and their distribution, as well as in studies of
owl behavior patterns. Based upon your data, what kinds of small animal populations do you think lived around
each of your owls?
2. Did you find any insects or insect parts in the owl pellet? Would you expect to find any? Why?
3. What are owl pellets?
4. In your own words, what happens to the soft part of the prey?
5. What is the purpose of the gizzard in the owl pellet formation?
Thinking Questions:
1. We know that about 50% of the energy in a mouse is not digested by the owl and is simply passed through as
waste (pellet) or feces. Is the energy stored in the pellet lost to the ecosystem? Why or why not?
2. At home, look up other birds that regurgitate pellets. Be prepared to list at least 3 other birds that also ‘vomit’
pellets.
Application:
1. Why does Don have to spray the corn starch on the owl pellets before sending them to schools?
2. Draw a possible Energy Pyramid to represent the owl and its prey.
http://dsc.discovery.com/tv-shows/dirty-jobs/videos/owl-vomit-collector.htm
http://www.kidwings.com/owlpellets/flash/v4/index.htm
1. Catching the prey
Before an owl pellet can start to be formed, the owl must first catch its prey. Owls are carnivorous and eat a
wide variety of animals including: birds, moles, mice, rabbits, skunks, frogs, insects, and much more.
2. Swallow the prey
Since owls do not have teeth, they can't chew their food. Therefore, they must swallow their food whole or in
large chunks.
3. Digestion
After an owl swallows its meal, it travels down the esophagus, then through the proventriculus, and finally into
the gizzard. In the gizzard, the meal is separated into two parts - those that are digestible and those that are not.
Digestible material continues to pass through the owl's digestive tract. Material that is not digestible are formed
into a rounded pellet.
4. Holding the pellet
After the gizzard has formed the pellet, it then pushes the pellet back up into the proventriculus. Here the pellet
is stored for several hours. Before the owl eats another meal, it must regurgitate the pellet inside the
proventriculus (since this would block the next meal from going to the gizzard).
5. Regurgitation
The final step for the owl is regurgitating the pellet. While the owl is regurgitating the pellet, it looks like it is
having difficulty breathing. Once the pellet is ejected, the owl settles back into a comfortable position.