Introduction: Owl Pellet Dissection
One of the units we covered this year in my Environmental Science class was energy and matter in the environment. The purpose of this activity is for students to understand how energy can be transferred in the environment. As an extra credit opportunity I encouraged my students to build their skeletons with the intention of creating 3D models that were labeled and enclosed in a small display case (students will make from acrylic/plastic sheets from the hardware store). We haven't gotten that far yet, but hopefully someone will take me up on the opportunity.
The owl pellet dissection can be repeated once or twice more (depending on your class size) over the course of a month or so for the purpose of collecting a sufficient amount of data for students to create data tables, charts, graphs in order to extrapolate information from the data collected.
This activity is one part of a whole unit and is written using 5th grade standards but can be adapted to younger or higher grade levels. What I really like about this lesson is that not only is it adaptable for grade level, easily differentiated for skills/abilities, it's also very accessible. There doesn't have to be a ton of background reading for students to all gain the same knowledge.
Additionally, this lesson can address multiple informational text reading and writing standards for English. Specifically researching barn owls (the type of owl our pellets came from), their usual diet and whether or not their diet changes based on where they live, how much barn owls typically eat and how often they eat.
NGSS.5-LS2-1.A Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.
NGSS.5-LS2-1.B Develop a model to describe phenomena.
MA.5-PS3-1 Use a model to describe that the food animals digest (a) contains energy that was once
energy from the Sun, and (b) provides energy and nutrients for life processes, including body repair, growth, motion, body warmth, and reproduction.
5.MP.2 Reason abstractly and quantitatively
MA.5.MD.B Represent and interpret data.
Newspaper, black paper, white paper
For students who may have compromised health or don't want to dissect a real pellet, they can use this virtual pellet.
Step 1: Trip
I wanted to make this unit as meaningful and hands-on as possible and attempted to do so in several ways.
The first of which was to arrange an up-close experience with owls for my students. I did this by contacting several organizations that had owls and settled on a local Mass Audubon sanctuary. Massachusetts has I don't know how many wildlife sanctuaries across the state and 20 nature centers. Several of these centers have wild animals that due to injury or human interference are unable to be released back into the wild and spend their lives at the centers, often acting as ambassadors for their species.
One of our local centers, Drumlin Farm, has several birds or prey and has a couple owl ambassadors. We were able to see a screech owl extremely close up. They were also able to see and touch owl and hawk wings, talons, and feathers (from deceased birds). We also talked a lot about owl diet and why they produce pellets. The Nature Teacher at the farm had tons of owl pellets she and her dog collected in the wild for us to look at.
Drumlin Farm is also a working farm in addition to a nature center/wildlife rehab.
The purpose of this trip was not only to get students exciting about our upcoming owl activities, but to activate their prior knowledge and to support them building new connections.
Step 2: Model
I think modeling is very important when doing something new (and when doing something that isn't new). I like to talk through my thinking and explain what I'm doing and why.
I did this with one owl pellet and recorded it so I could turn it into a test and review material for later.
I start by laying out my work area and explaining why things are set up the way they are. Why I have newspaper down, the importance of gloves, safety etc.(Massachusetts Science standards have a whole page dedicated to owl pellet dissection safety) and then I model how to pull apart the pellet and how to use the tools. As well as techniques for finding super small bones.
Step 3: Prep
For the owl pellet dissections, I tape down newspaper for the students to work over.
For dissecting the pellets students are given disposable gloves (new ones each day), a tray with a lid of keeping their pellet in and another tray with lid for keeping their tools in.
Pellets come heat treated and wrapped in tin foil, but for safety reasons they should not be handled without gloves.
We used plastic salad containers from our cafeteria for the trays.
Step 4: Sorting
Students were given sheets of black paper and white paper, to pull apart the pellets and have an easier time seeing the bones. I encouraged them to find all the bones from their pellets before trying to decide what type of animal the bones came from.
Students sort the bones and use bone identification charts to figure out what type of diet their owl ate. I ordered pellets from the Northwest US and the Southwest US, hoping students would find different animals in their pellets.
I included a couple links to bone sorting charts under the supplies list, but a quick google search will yield dozens of bone charts. They're all pretty much the same and represent the most common animals owls eat (voles, shrews, etc.). I gave my students 4-5 charts they could choose from.
Step 5: Identification
Once all the bones were sorted from the pellet fur, they worked on matching the bones up with the bones on their identification chart to determine what type of animal/s was in the pellet.
Depending on the pellet size you order, you could find bones from 2-3 different animals. You also might not. One of my students had two skulls in their pellet, another had one, another had none. Remind students that they can't assume all the bones they find are going to match one skeleton on the chart.
Step 6: Data Collection
After students sorted and identified the bones in their pellets, they each charted the type of bones they found and how many. Then they collected the data from their classmates to make a data table comparing the information they gathered from their pellet with their classmates. As well as comparing the differences between owls from different parts of the country.
The data collected can be compiled into a google spreadsheet for all to access and review.
Examples of the type of data collected are: size of pellet before dissection (inches/cm), weight of pellet (g), weight of bones, types of animals, number of each animal found, total mass of animals, consumption requirements, etc. You can make add more or less data points depending on the level of your students.
Students then used the information collected to create owl food webs and explain how matter and energy are transferred among organisms and ecosystems. To better address the NGSS.5-LS2-1 standard, models should include additional tropic level information (sun, producers, decomposers).
Second Prize in the
Classroom Science Contest