Bird Dissection Worksheet by tna55004

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									Owl Pellet Dissection
             Owls of Maryland
•    Five species of owls
     live in or pass
     through Maryland.
1.   Barn owls
2.   Great Horned owl
3.   Barred owls
4.   Eastern Screech owl
5.   Northern Saw-whet
     owl
• Owls have special                Adaptations as
   adaptations that enable
   them to hunt at night.            predators
1. Their eyes are large and
   fixed, with binocular vision
   and good depth
   perception.
2. Because owls are unable
   to move their eyes, they
   have developed an
   incredibly flexible neck that
   allows them to turn their
   head 270 degrees in both
   directions.
3. Their eyes are also
   extremely light sensitive,
   allowing them to see well
   at night.
              Owls as predators
4. Owls rely on silent flight
   to surprise their prey.
5. The shape of the owl’s
   flight feathers muffles
   the sound wind makes
   as it flows past them.
6. These are all perfect
   adaptations for finding
   and catching prey at
   night, and explain why
   owls have become the
   most efficient “hunters of
   the night”.
 The
Food
Web
• 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.
                                                    Owl
• Owls, on the other hand, do not have teeth
  for grinding and cannot pass whole bone
                                                   Pellets
  and claws through their digestive tract
  safely.
• The protein enzymes and strong acids that
  occur in the digestive tract of raptors do not
  digest the entire meal.
• The relatively weak stomach muscles of
  the bird form the undigested fur, bones,
  feather etc. into a bolus (or wet slimy
  pellets).
• 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 passed from the body. In this
  process even the most fragile bones are
  usually preserved unbroken.
• The owl pellets that you will be
  examining in this lab have been
  collected and fumigated from
  common barred owls.
• Owl pellets themselves are
  ecosystems, providing food and
  shelter for communities that may
  include clothes moths, carpet beetles
  and fungi.
• Moth larvae are frequently abundant
  in pellets, feeding on fur and feathers.
  The black spheres about the size of
  periods (.) that are found in the
  pellets are the droppings of the
  caterpillars. The larvae
  metamorphose near the surface of a
  pellet in cocoons made of fur.
• Ecologist examine owl     Owl Pellets
  pellets to estimate the
  diversity of prey
  species
• Important information
  for species
  management and
  protection
• The contents are a
  direct indicator on
  – What the species has
    fed upon.
  – Species richness
  – Species abundance
   Estimating Species Diversity
• Species richness: the   Common   Genus        Freq
                          Name                  Found
  total number of         Vole     Microtus     70%
  different species       Shrew    Sorex        20%
                          Mole     Scapanus     5%
• Species abundance:      Deer     Peromyscus   2%
                          Mouse
  the abundance (%) of
                          House    Mus          2%
  each species            mouse
                          Rat      Rattus       1%
                          (small   Hirundo      rare
                          bird)
Common Genus        Freq
Name                Found
Vole     Microtus   70%
Shrew    Sorex      20%
Mole     Scapanus   5%
Deer     Peromyscus 2%
Mouse
House    Mus        2%
mouse
Rat      Rattus     1%
(small   Hirundo    rare
bird)
                             Worksheet
Type and #       Microtus   Sorex   Scapanus   Rattus   Peromyscus or Mus
                                                                            Bird
of bones         Vole       Shrew   Mole       Rat      Mice




Skulls




Jaws




Shoulder blade




Hips




# of animals
                          Prey Analysis Data chart



         Habitat   Mea    Conversion   Frequency   Percent   Biomass   Percent
Prey               Mass      Factor       Found    of Diet   Units     of
                   (g)                                                 Biomass
Meadow   meadow     40    2
Vole
House               20    1
Mouse
Deer                20    1
Mouse
Mole                55    2.75
Shrew                5    .25
Rat                 240   12
Small               40    2
Bird
                          TOTALS                   100%                100%

								
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