Owl Pellet Essentials Dissection Lab

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Exploring Prey & Predator Relationships

Owl Pellet Dissection Lab


Owl Brand Discovery Kits

ts The Formation of Owl Pelle

1 9

8 10 2

3 4 6 7

1 Proventriculus

4 Pancreas

2 Ventriculus (gizzard)

5 Intestines

3 Liver

6 Cloaca 7 Vent

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5

8 Kidney 9 Heart 10 Lungs

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Owl pellets are a product of the unique digestion system of birds. Owls and other birds cannot chew their food as many animals do. They have to swallow their smaller prey whole and tear larger prey into pieces. An owl’s food travels directly into their digestive system.

Bird stomachs consist of two parts. The first part is the glandular stomach or

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proventriculus,

which produces enzymes, acids, and mucus that begin the process of digestion.

The second part is the muscular stomach, called the 2

ventriculus, more commonly called

a gizzard. There are no digestive glands in the gizzard. In birds of prey, the gizzard is useful as a filter, holding back insoluble items such as bones, fur, teeth and feathers.

The softer parts of the bird’s diet are ground by muscular contractions, and allowed to pass through to the rest of the digestive system, which includes the 5 small and large intestine. The 3

liver

and 4 pancreas secrete digestive enzymes into the small intestine where the food is absorbed into body as energy.

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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At the end of the digestive tract (after the large intestine) is the 1

Cloaca (klo-A-ka), a holding area for Uric acid,

also know as Urea. Urea excretions are the white bird droppings we see on buildings and below perches. This form of excretion helps minimize water loss.

The cloaca opens to the outside by means of the 2

vent. Several hours after eating, the indigestible parts (fur, bones, teeth & feathers that are still in the gizzard) are formed into a pellet the same

shape as the gizzard. This pellet travels up from the gizzard back to the proventriculus where it can remain up to ten hours before being gagged up.

Scientists have concluded that the pellet remains in the bird’s system until all the nutrition has been absorbed into the bird’s system. Typically, an owl will not eat more prey until it has emptied it’s system of the previous meal. If they do eat more, that food will be compacted into the previous remains. For that reason, pellets can range in size from under an inch to as many as four inches, and contain up to 4 to 5 prey!

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How does the Owl Expel the Pellet? When the owl is ready to gag up the pellet, it will turn its head at an angle or to the side and open its beak. Owls will often close their eyes and the facial discs will narrow. They rarely leave their perch during this process. Stretching its neck, the owl’s beak opens wide and the pellet pops out with little fanfare.

Owl Pellet

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Owl Brand Discovery Kits

Owl Pellet Dissection Lab Barn Owl pellets have been chosen because these owls swallow small rodents and birds whole, and the resulting pellets generally contain the complete skeletons of their prey. Pellets begin forming within the digestive tract of an owl as soon as the prey is swallowed. Enzymatic juices break down the body tissues in the prey but leave the bony materials and hair or feathers undigested. Depending upon the prey eaten, the undigested portions may include beaks, claws, scales, or insect exoskeletons. This type of material has little nutritional value and must be “gagged” from the system. Predatory mammals such as bobcats and wolves have teeth to grind up bones and claws, and a digestive tract adapted to pass these ground parts. Owls, on the other hand, do not have teeth for grinding and cannot pass whole bone and claws through their digestive tract safely. Instead, these materials form a pellet that is surrounded with the hair or feathers of the prey consumed. The pellet is then orally expelled, or gagged, and the owl begins feeding again.

You will need the following items in order to conduct a Barn Owl Discovery Kit Pellet Lab: OBDK Bone Identification Charts Pencil Clean sheet of paper Two probes Tweezers Magnifying glass Paper towels Antibacterial wipes White glue Tub of water diluted bleach

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To aid in prey identification To record findings To place extracted bones on To loosen fur from bones To extract bones away from fur To identify bone type To absorb excess water To sanitize work station To secure bleached bones to bone chart To whiten extracted bones

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p ur p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .


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Scientists and teachers take advantage of this unique process by collecting these pellets and examining their contents. Since owls are not very selective feeders, these pellets can be used in a variety of instructional settings. The contents are a direct indication of what an owl has fed on. A one-year study of a particular Barn Owl revealed the following diet: 1,407 mice, 143 rats, 7 bats, 5 young rabbits, 375 house sparrows, 23 starlings, 54 other birds, 2 lizards, 174 frogs, 25 moths, and 52 crickets.

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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Constructing a Food Web Animals that eat other organisms for energy and growth are called consumers. There are three consumer levels found in a food web: primary, secondary and tertiary. Primary consumers are usually herbivores; they feed on photosynthetic products such as grass and seeds. Secondary consumers gulp down primary consumers. And tertiary consumers (carnivores) devour secondary consumers and are usually found at the top of the food chain. Here is an example of a food web including the Barn Owl.

Exercise 1: What other carnivores and herbivores would you add to the food web? Listing these others, construct a food web, with the Barn Owl at the top.

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What’s on the Outside? Before you dissect the pellet, examine the outside of the pellet for clues to where it was gathered. Pellets are collected from a variety of places around the country. Use the chart below to see if you can determine where the Barn Owl might have gagged your pellet. What you might find: Milo Seeds → Grain → Dirt → Hay or Straw → Feathers → Pine needles →

Where owl gagged the pellet: Open sheds Grain elevator Cut banks and under trees Barns and hay sheds Man-made nesting boxes Under evergreen trees

Exercise 2: 1. On your piece of paper, write down the clues that might indicate where your pellet was gathered. 2. Can you identify other items stuck to the outside of the pellet?

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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Owl Brand Discovery Kits

What’s on the Inside?

Exercise 3: Label a clean sheet of paper for each pellet you dissect, for example, pellet one, pellet two, etc. Note: If you find that the pellets do not come apart easily, you can soak them in warm water to soften them.

Using the probes provided, begin to loosen the hair of the owl pellet. As bones are uncovered, carefully remove them using your tweezers and place them onto a properly labeled sheet of paper. Take extra care to keep skulls intact and near the mandibles (see Owl Brand Discovery Kit Bone Identification Charts). Continue to extract bones from the hair of the prey. Once you have found all the bones, you can begin identifying them by comparing them to the illustrations on the charts provided.

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© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p ur p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .


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Bleaching & Mounting the Bones to your Owl Brand Bone Identification Charts

Exercise 4: 1. Keep the bones from each prey item separate by setting each set onto a separate clean (labeled) sheet of paper. 2. Place the bones into a tub of diluted bleach to whiten them. (Bleaching is Optional) 3. After the bones have been cleaned, set them onto a separate dry paper towel. 4. Using a magnifying glass and the Owl Brand Discovery Kits Bone Identification Charts, try to identify the type of skeleton that was found in your owl pellet. 5. Use white glue to attach the bones to the correct Bone Identification Chart.

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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Owl Brand Discovery Kits

BIRD

CLAVICLE

MANDIBLE

SKULL (top view) ULNA FEMUR

FIBULA RADIUS TIBIO TARSUS

SCAPULA

PELVIS

HUMERUS

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© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p ur p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .


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MOLE

Scaparus orarius

MANDIBLE

CLAVICLE

FIBULA

HUMERUS SKULL (top view)

TIBIA FEMUR PELVIS

SCAPULA

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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Owl Brand Discovery Kits

MOUSE Microtus

CLAVICLE

SKULL (top view) SKULL (side view)

FEMUR

FIBULA

RADIUS

TIBIA

SCAPULA

ULNA

HUMERUS PELVIS

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© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p ur p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .


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RAT

Microtus CLAVICLE

SKULL (side view)

FEMUR

FIBULA RADIUS TIBIA

SKULL (top view)

ULNA

HUMERUS

SCAPULA PELVIS

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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Owl Brand Discovery Kits

SHREW

Sorex vagrans

MANDIBLE

CLAVICLE ULNA RADIUS SKULL (top view) HUMERUS

TIBIA FIBULA

FEMUR PELVIS SCAPULA

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© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p ur p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .


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VOLE

Microtus

CLAVICLE

FIBULA

TIBIA

MANDIBLE SKULL (top view)

RADIUS HUMERUS

ULNA

FEMUR PELVIS SCAPULA

© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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Owl Brand Discovery Kits

NOTES:

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© 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p ur p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .


Owl Pellet Essentials Guide for Teachers and Students.

Recognizes:

Student Name

Date

For the completion of the

Owl Pellet Dissection Lab Teacher

Grade

School

www.obdk.com © 2 011 O w l B r a n d D i s c o v e r y K i t s . A ll r i g h t s r e s e r v e d . R e p r o d u c t i o n p e r mi s s i o n f o r e d u c a t i o n p u r p o s e s o nl y a n d n o t f o r r e s al e o r c o m m e r c i al u s e w i t h o u t s p e c i f i c p e r mi s s i o n .

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Proudly Presents: Running For Home

Education is not for the timid. It is rarely the impartation of our knowledge or a citation of our credentials, although we each are tempted to choose that approach. More commonly, effective education is the ability to inspire and engage our students and compel them to become an actual part of “Theetymology the story. The howling of theof eduis the voice of my bro wind thers.”of cation includes Auth expressions or Unknown breeding and rearing up; early forms of education, before written word, involved imitation as a central tool of passing knowledge to future generations.

Running for Home

Can you find the hidden animals in this book, including the two on this cover?

by Gail McDiarmid &

Marilyn McGee

Illustrated by Durwood Coffey

At Owl Brand, we want to celebrate those who we think do it well. Being an educator requires something from each of us that transcends cultures, fashion, trends, and instead embraces the timeless skill of storytelling. When stories are told with distinct traits of humility, contagious enthusiasm, and a purposeful result–a moral, the story can become a life lesson that remains in our consciousness. When I first met authors and sisters, Gail McDiarmid and Marilyn McGee, I knew they shared our concern for the complex issues facing our future in effective ecology stewardship. I met them through the


introduction of their engaging book titled Running for Home. That introduction resulted in an invitation to present at the 2013 Summer Celebration we co-host each summer in Idaho. They traveled from the across the country to Idaho where their goal was to present Running for Home, a book that tackles the story of ecology through lovable characters Chinook the wolf, Wapiti the elk and the hilarious raven Mochni. The outcome was my outright adoption of their important message and their contagious enthusiasm. I’m excited that Gail and Marilyn will return to help us reach more children with their great message and fun style of teaching, inescapably central in the book.


I’m so privileged to recommend this fantastic book. Gail and Marilyn were so very kind to let Owl Brand participate in their creative journey through the talents of our graphic artist and friend of ecology, David Winfield. The story is compelling, but just as important, these sisters work with a depth of compassion and conviction--not just for the real life subjects depicted by their characters but also for the audience. When a well-told story and young minds come together, the result can be profound. That’s an investment I can get excited about. I hope you’ll consider it for your classroom. Happy Reading!

Chris


Running For Home (excerpt)

A

young elk stands dangerously close to the edge of a deep gorge cut by the roaring Lamar Rive r in Yellowstone National Park.

“Wapiti!” screams the elk’s mother as Every spring as the snow melts, the she runs to her son. Suddenly, the ground rivers of Yellowstone rush over the barren collapses beneath his spindly legs and landscape leaving huge crevices and Wapiti plunges into the raging river. ditches. Hundreds of elk graze in one Gasping for breath, he surfaces, but the area and consume the river-loving woody water pulls him back under. The thirtyplants, especially the cottonwoods and five pound youngster is on the verge of willows, rarely allowing their tender being swept away. He kicks and jumps shoots to grow tall. The elk’s sharp, pointfrantically and finally makes it safely to ed hooves trample the roots which would the debris-covered embankment. have helped to anchor the soil and slow “Son, are you hurt?” his mother cries, down seasonal runoff. The absence of nudging him up the bank to dry ground. one keystone species in the Yellowstone As he shakes the water from his tawny ecosystem contributes to this problem. brown coat, she says, “You have to stop But that is all about to change. Missing wandering away.” for over seventy years, the elk’s primary “I’m sorry, Mom. I just wanted to see predat or has returned to teach little Wapiwhat was down there.” ti and his herd how to run. The movement “Rivers are dangerous places for of the elk away from the rivers will allow little elk,” his mother says. the vegetation to grow, restoring the health of the riverbanks. Renewed again, the timeless agreement between these two animals will help to sustain life in the valley.

clues. recap those Now, Let’s ystery animal: The m

“What wa screams s that?” Mochni.

3

like...Wind 1. Sounds through g lin w ho the trees en eyes 2. Has gold “I don’t know,” exclaim s Chinook .

his food 3. Shares rs with othe k on the 4. Keeps el move

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