• Answer either the pre-lab questions or the questions in Part A of the Lab Report. Your instructor will let you know which set of questions to answer.
• Utilize your own senses and whatever field tools you may have available to explore the ecosystem chosen by your instructor.
• In your Lab Report, make scientific observations and sketches of the type and number of species in each level of the ecosystem you visited.
• Create a trophic structure and a food web for the ecosystem you visited.
• Answer questions in Part B of the Lab Report.
• Your instructor may direct you to complete the Remote version of this Part B instead.
• Owls are predatory carnivorous birds, feeding on herbivores and primary carnivores alike.
• Like other predatory birds, owls are swift, agile fliers with keen eyesight for catching prey. However, unlike other birds of prey, such as hawks and eagles, that use sharp beaks to rip the meat from bones, owls swallow their prey whole.
• However, since the owl is unable to digest the hair, feathers and bones of its prey, they must be excreted and owls do this in a very peculiar way! Owl pellets are regurgitated clumps of undigestible bone, teeth, hair, or fathers of various prey eaten by the owl.
• Usually it takes about 20-24 hours for an owl to produce a pellet after feeding.
• Therefore, ecologists can use owl pellets to learn about owl adaptations and their habitats. Although owl pellets are considered the waste product of the owl, the pellets themselves also provide a habitat for other organisms such as moths, beetles, and fungi.
• In this exercise you will dissect a commercially sanitized owl pellet and identify its contents.
• Remember that one owl may eat several prey each night so don't be surprised if you find the skeleton of more than one species in your pellet!
1. Scientifically observe the sanitized barn owl Pellets you have been given. Remember scientific observations utilize quantitative measures whenever appropriate. Measure the length and width and mass of your owl pellet.
2. Examine the exterior of the pellet. Are there signs of fur or feathers?
3. Carefully use your forceps to break apart the owl pellet. Be gentle and do not push harder than necessary. Remember, the bones are small and will be easily broken. Observe the interior. Carefully use the wooden probe to pick out and expose any bones for identification. The easiest bones to spot are the skulls (look for teeth or beak) and pelvic bones. Set aside any bones you find.
4. Compare the bones with those pictures on the owl pellet bone chart.
5. Mount the bones on paper with glue. Label each bone by type and species when possible.
6. Compare your bone findings with your classmates. Does it look like all the owls had a similar diet?
• Complete Part C of the Lab Report.
Non-majors College Biology Lab Manual © 2021 by Marie McGovern Ph.D. is licensed under CC BY-NC 4.0