Alabama Science in Motion pellet

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                                  OWL PELLETS
                              TEACHER HANDBOOK

Course of Study - Science
Biology – 1,13
Environmental Science – 12
Zoology – 3,7,8,9

          Ask students what they know about owls. Give each student an index card
           and instruct them to work with their partner to list as many things as they can
           about owls.
          Ask student groups: Owls must eat about ¼ of their body mass each night.
           How can you discover what they ate in their last meal?
          Show the video clip from Dirty Jobs about owl pellets.
          Watch the video “Ecology of a Barn Owl.” Tell students that they will be
           asked to add to their original list after the video, so they should pay close
           attention. (As an alternative, choose some of the owl clips on
  to share with your
          Ask partners to return to the list and cross off any misinformation they may
           have listed and to write 5 new things they learned about owls from the video.
          Optional: Pass out the handout containing questions from the Owl Pellet
           Video. Instruct students to answer these questions for homework. Page 7 of
           teacher section)
          Quiz students with true/false questions about owls and/or owl pellets (see
           examples on page 8 of the teacher section). Give students a picture of an
           arrow that has been duplicated on card stock (page 9). Students point the
           arrow upward if they think the question is true and downward if they think the
           answer is false.
          Tell students you will be trying to answer this question from the lab
           experience: “What types of valuable information could be provided by
           studying an owl pellet?”

Part I Prep:
Remind students to wash their hands before leaving the lab.
1. Set up the top-loading balance to allow a 30-minute “warm up” time before use.

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2. Distribute the materials to the student groups; bottles of glue should be shared among
    student groups.
3. It is helpful to run the Identifying Owl Pellets Contents (page 4) off on card stock. It
    works better with glue than regular paper.
Prelab:         Less than 1 class period – depending on usage and type of AV material.
Lab:            1 class period (additional time will be needed to complete the analysis
Postlab:        .5 - 1 class period
Group Size: 2 - 4 students/group

      Discuss the students’ lab sheets. In particular, discuss what the students felt they
       could learn from studying owl pellets.
      At this point, if discussion does not elicit the information you want, share with the
       students the data collected by the class and that by studying the contents of owl
       pellets, one may discover seasonal, regional, and habitat differences and even
       differences in individual tastes between owls.
      Also, pellets can be used to effectively illustrate the nature of food chains, to
       demonstrate the role of avian predators within the ecosystem, and to provide
       information about the presence and relative abundance of animals in a particular
      Pellets can also be used to introduce students to skeletal anatomy and to teach
       them how to identify an animal by its skull and jawbones.

      Students’ lab procedures.
      Students’ answers to questions from the Introduction and the Lab itself.
      Students’ answers to the Owl Pellet video.
      Students’ food webs
      Students’ answer to extension activity 1

Anticipated Answers of student analysis questions
Table 1 and 2 and 3 – answers will vary
Analysis – graph will vary
2. answers will vary
3. Young: 3 x 5 x 30 = 450
   Adults: 2 x 4 x 30 = 240
4. they are toward the top of their food chain
5. pictures will vary, but plants (level 1) should be at the bottom (level 1) of the chain,
    (level 2) spiders, grubs, earthworms, centipedes, crane fly,
    (level 3) voles, deer mouse, moles, house mouse, shrews, frogs and salamanders
    (level 4) weasels, snake, starling
    (level 5) the owl should be located at the top of the food chain
6a.what the owl consumed that day
    the diet of the owl, distribution of various animals, the skeleton anatomy of their prey

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7. regurgitated food that cannot be chewed
8. eaten & digested by the owl
9. hard, non-digestible parts are compressed – bones, teeth, fur, feathers, chitonous
    remains of insects
10. proventriculus
11. feces, mouth
12. hawks, eagles, kites, harriers, falcons, robins
13. owls, birds
14. 1-2/day
15. glossy black
16. color, dried
17. Tytonidea
18. eliminates insects (and also fungus)
19. food chains trace energy in a straight line from the producers to the top consumers;
    food webs show the energy flow through different organisms and their dependency in
    an ecosystem
20. if the number of organisms, in each of the lower trophic levels, was the same or
    greater, there would not be enough food to support the higher trophic levels
21. one major loss of energy is the inefficiency of digestion – approximately half the
    energy stored in an organism is never digested by the consumer. Other major energy
    drains are food acquisition, digestion and cellular respiration.
22. no, not all of the energy is lost. The decomposers break down the feces into other
    compounds that can be used by plants to produce organic molecules that store energy.
    Some energy is lost during this process in the form of heat

Answers to Barn Owl Video:
1) uric acid buildup                         7) mate
2) presence of pellets and whitewash         8) oldest
3) early spring                              9) 8 weeks
4) 1 maybe 2                                 10) arrangement of facial feathers
5) 4-7 usually could be 1 or 13              11) 4
6) eggs are laid in 2 day intervals          12) owl pellet

      The following questions/activities could be used to extend this lesson further:

           1. Ask students to list one question for further study which they would like to
           2. How can a CSI unit determine the last meal of a victim?
           3. Using the picture and glue provided in your lab, reconstruct the skeleton
              of a rodent eaten by an owl.
           4. Complete the attached Activity #1 to see the effect an owl can have on the
              rodent population.
           5. Complete the attached Activity #2 to make a food web.
           6. This would be a good time to incorporate the J9FoodWeb lab.
           7. Anatomy teachers could use this lab for identifying bones.

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                                    ACTIVITY #1
In our experiment, we dissected 6 owl pellets from 1 owl. Use this information to
determine the average number of mice an owl eats in a day, a week, a month, a year.
Pellet 1       Pellet 2    Pellet 3     Pellet 4      Pellet 5     Pellet 6
1 mouse        3 mice      1 mouse      2 mice        2 mice       3 mice
  1. What is the average number of mice in each pellet?                          (2)
  2. Owls make 2 pellets each day. How many mice are eaten in one day?           (4)
  3. How many mice does our owl eat on average in a week?                        (28)
  4. How many mice does our owl eat on average in a month (30 days)?             (120)
  5. How many mice does our owl eat on average in a year (365 days)?             (1460)
That's a lot of mice for one owl to catch and eat in one year. But what about feeding a
whole family of owls? Try to answer the following problem.
Suppose there is an owl nest that has six young owlets. Until the owlets are three weeks
old they eat half as much as their parents. After three weeks, they eat as much as an adult.
After nine weeks the owlets are big enough to fly and hunt on their own. How many mice
would it take to feed this family for those nine weeks? Don't forget, the parents need to
eat, too!
Owlets - First three weeks:   (eat half as parents)
1. Number of owlets?                                                                 (6)
2. How many mice does one owlet eat each day?                                        (2)
3. Number of days in 3 weeks?                                                        (21)
4. How many mice do the owlets eat in three weeks?                                   (252)
Owlets - Next six weeks:     (as much as parents)
5. Number of owlets?                                                                 (6)
6. How many mice does one owlet eat each day?                                        (4)
7. Number of days in 6 weeks?                                                        (42)
8. How many mice do the owlets eat in six weeks?                                     (1008)
Parents - Whole nine weeks:
9. Number of parents?                                                                (2)
10. How many mice does one parent owl eat each day?                                  (4)
11. Number of days in nine weeks?                                                    (63)
12. How many mice do the parents eat in nine weeks?                                  (504)
13. How many mice were needed to feed this family for nine weeks?                     (1764)
14. How many mice will this family of eight consume in a year? (11428 if students
    allow for owls eating half as much food for the first 21 days; if not, answer is 11680)

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                                   Activity #2
                                 HOO EATS WHO
                               MAKING A FOOD WEB

Items Needed:     copy of animal figures sheet
                  tape, glue, or paste
                  blank paper (11”x17”) or poster board
                  pencil, pen, or marker

Turn a large sheet of paper in the landscape format. Draw grass, seeds, flowers, and
plants on the bottom.

Cut out the animal figures. Affix the owl to the top of your good web.

Arrange the other animals on the page with space to draw arrows in-between. Put grass
and seed eaters near the bottom. When they are all arranged, paste or tape them in place.

Draw arrows from each item to the animal that eats it. You may want to draw in other
items such as worms (eaten by moles, shrews, and birds).


Owl             eats      field mouse, vole, bird, shrew, mole, lizard, grasshopper,
                          beetle, moth

Field Mouse     eats      grass and seeds, grasshopper, beetle, moth

Vole            eats      plant roots, grass and seeds, grasshopper, beetle, moth

Bird            eats      seeds, grasshopper, beetle, moth

Shrew           eats      grasshopper, beetle, moth

Mole            eats      grasshopper, beetle, moth

Lizard          eats      flowers, seeds, grasshopper, beetle, moth

Grasshopper     eats      leaves, grass, seeds

Beetle          eats      leaves, flowers, seeds

Moth            eats      flowers

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                   OWL PELLET VIDEO
   1. What is Whitewash?

   2. What is a sign of a barn owl nest?

   3. When do most barn owls nest?

   4. How many mates does a barn owl usually have?

   5. How many eggs can be laid in the barn owl nest?

   6. Why do barn owls hatch at 2 day intervals?

   7. Who does the mother depend on for food?

   8. If there is a food shortage, which owl gets the food?

   9. How old are the fledglings when they leave the nest?

   10. What is the secret behind the barn owls excellent hearing?

   11. How many claws are on each foot?

   12. The bolus from the barn owl is typically called an ________

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Possible true/false questions that can be used for quizzing the students before completing
the lab.

1. An owl pellet is regurgitated undigested food, not feces.      TRUE
2. A pellet remains moist and soft until it is outside the owl’s body. TRUE
3. Using its digestive juices and chewing the prey, the owl is able to comfortably reduce
    the size of the pellet.
        False – does not chew food
4. After eating its prey, it takes the owl about 18-20 hours to form a pellet. TRUE
5. It takes the owl anywhere from several minutes up to one hour to actually regurgitate
    the pellet upward through its digestive system.
        False – takes a few seconds up to 2-3 minutes
6. Once the pellet is formed, an owl can not eat new prey until the pellet is ejected.
7. Because of their ability to see by moonlight and their sensitivity to light, owls tend to
    feed at the darkest time of the night.
        False – owls feed in the early evening
8. Most pellets contain 52% fur/feathers and 48% bone. TRUE
9. An owl does not have a crop. TRUE (true)
10. The pellet remains in the proventriuculus before being ejected. TRUE
11. Owls can turn their heads all the way around.
        False. All owls have eyes that are fixed in the sockets, so they must be able to
        turn their heads to see. However, they can only turn their heads about 270
12. If owls were the same size as humans, their eyes would be the size of grapefruits.
        TRUE. The eyes of an owl are about the same size as human eyes. Compared
        to their head and body size, their eyes are extremely large.
13. The male owl is generally stronger than the female.
        FALSE. Female owls are usually larger, and therefore, stronger than the

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