Owl Pellet Dissections (Ashley Winkler)
Owl Pellets!!
Principles investigated/objectives:
Students will dissect an owl pellet for the purpose of collecting bones and assembling a scale model rodent/bird skeleton. They will be required to identify the bones and collect class data to analyze. They will also do basic research on characteristics of owls and construct a food web based on information gathered from their research.
Standards:
Junior High:
Structure & Function in living Organisms
7.5.a students know plants and animals have levels of organization for structure and function, including cells, tissues, organs, organ systems, and the whole organism.
7.5.b Students know organ systems function because of the contributions of individual organs, tissues, and cells. The failure of any part can affect the entire system.
7.5.c Students know how bones and muscles work together to provide a structural framework for movement.
7.5.g Students know how to relate the structure of the eye and ear to their functions.
7.7.c communicate the logical connection among hypotheses, science concepts, tests conducted, data collected, and conclusions drawn from the scientific evidence.
7.7.d Construct scale models, maps, and appropriately labeled diagrams to communicate scientific knowledge.
High School:
Ecology 6.
e. Students know a vital part of an ecosystem is the stability of its producers and decomposers.
f. Students know at each link in a food web some energy is stored in newly made structures but much energy is dissipated into the environment as heat. This dissipation may be represented in an energy pyramid.
Materials:
Gloves
Tweezers
Probes
Bones chart and bones data table
Owl fact sheets
Excel or word graphics-to make charts/graphs
Construction paper
Decorative/construction items for project: glue, scissors, colored paper, markers
Dilute bleach to clean/whiten the bones after collection
Several small beakers-to bleach bones in
Procedure:
1. Pre-lab before hand, going over introduction to owl pellets, what they are and where they come from. Also talk to the students about safety and clean up procedures
2. Pass out pellets to groups of 2 students. The first day the pairs will dissect the pellets using tweezers and probes separating bones from unwanted materials (fur, feather, etc.)
3. The pairs should put their bones into a labeled beaker for the teacher to bleach before the next class
4. The next class the students will learn about food webs and be given information to construct their own owl food web.
5. The students will use factsheets provided by the teacher to research particular characteristics or traits of the owls where they will summarize 5 important facts they found.
6. Students will take their cleaned bones and either construct a skeleton out of them or make a bones chart where each type of bone is identified and labeled.
7. Finally students will compile all of the work and put a poster together to present to the class at the end.
8. The final part of the poster is the graphed class data on all of the different animals found in the pellets.
9.
Student’s Prior Knowledge:
¨ Students should have recently covered the organ systems. They must be familiar with levels of organization of living organisms: Cells to tissues to organs to organ systems to organisms.
¨ Students must be familiar and able to identify several bones (learned during the skeletal system)
¨ They should have a basic understanding of the digestive system and be aware that organ systems work together to provide necessary life functions.
¨ Students also should understand the basic structure and function of the eye and ear. This will help them when researching the owls and their physical characteristics.
¨ Many students will be familiar with food webs/food chains, but it is not a necessity for this project, as the teacher will have the opportunity to teach them during this project.
Explanation:
The owl pellet dissection can be an activity to reinforce several different concepts and you can tweak the dissection to cover a lot of different topics depending on your own purpose. But… I think this is a really great way to incorporate many topics.
The students will do the actual dissection in pairs. They should separate bones from fur, feathers, or whiskers (yea I said whiskers…occasionally there are some!) The dissection should be done during one class. When the class period is over put each groups bones into one small beaker and cover with the dilute bleach solution to clean and whiten the bones for the next class.
The next class has several components to completing the project. The students are going to make an owl poster. First the students compile their data (# of types of bones and from which rodents presumably) and compile a class data table. The teacher can them demonstrate how to enter the data into excel and create basic graphs for the students to incorporate onto their posters illustrating their findings.
Example table that could be used:
Example graphs that could be formatted:
Posters must contain a reconstructed skeleton of whatever animals/birds they may have collected. Or the students may opt to do a sorted bones chart on their posters. Each pair is given fact sheets on a particular species of owls and they must write a short summary of facts: habitat, diet, physical characteristics, behavioral physical adaptations, etc.
The poster must also contain a food web, which the students will do using a template given by the teacher. Also note, before this portion of the project is done the teacher will give a brief overview and lesson on food webs and energy pyramids.
The students will have the opportunity to present their posters to the class during the next class time. At the end of the entire project, the teacher should go over some basic characteristics the students observed (both in the skeletons/bones and from the research they did on owls) that reinforce what students had recently covered. (Specific bones, ratios of sizes of bones, eye/ear anatomy of owls, food webs, etc.)
Questions & Answers:
1. Why do you suppose owls regurgitate these pellets?
A: Owls are not able to digest certain materials such as fur, feathers, and bones. So those materials are compacted into these small pellets and get coughed up in order to get out of their system as well as to make space for additional prey to be consumed. If they can’t digest it, the only other way for it to go is up and out!
2. According to what you have seen and dissected out of your pellets, what does this tell you about your owl’s diet?
A: Owls eat their prey whole. They feed on small rodents and birds and eat many in one night as you can see from the several skulls uncovered in the pellet. They also have to regurgitate these pellets before they can eat more.
3. Now we have all collected our data, identified the bones, and even the animals they belonged to. What are some of the ways we can analyze the class data to get a better idea of what the barn Owls diet consists of? Do you think our class data is an accurate representation of Barn Owl diets overall?
A: We could compile the number of each kind of rodent/bird each group dissected from the pellets and find out what percentage of the class total that animal accounted for.
Ex. % of field mice in the barn owls diet according to our class data:
(# of field mice/ total # of animals identified)x100=_______%
Then we could put all of those numbers either percentages or the actual number value for each animal into a graph to create a visual breakdown of the owls diet. You could use bar graphs or even pie graphs.
The data may not be representative of everything a Barn Owl might eat, because they may have been barn Owls from one location, but not many different locations. Therefore we may have only seen a normal diet of a Barn Owl that lives in one spot.
Applications to Everyday Life:
¨ This is a great illustration of the nature of food chains and energy flow.
¨ The students get to see what kind of role owls (and other bird predators) play in the ecosystem and look at how species differ from one geographical location to another.
¨ Students also get to use this activity to identify bones they are already familiar with and then identify animals they may have come from that are common in our areas.
Photos: