NAME: _____________________________BLOCK:_______DATE:_________
Lab: Pigeon Dissection
Introduction:
Birds, are “glorified reptiles” that bear the stamp of their reptilian heritage in many subtle
ways. But birds have become so highly specialized into flying machines with all the constraints
that design for flight requires. The demands of flight, far more than anything else, have shaped
the form and function of birds and have disguised their reptilian past. Virtually every
adaptation found in flying birds focuses on two features: power and less weight. The skeletal
system is lightweight and very strong. The flight muscles of the chest may make up one fifth of
the total mass of a bird’s body. Birds have extremely great energy requirements because of
their high metabolic rate. The unique air sacs of their respiratory system provide them with a
continuous supply of oxygen. I line with their needs for a streamlined, lightweight body, bird’s
reproductive organs are small and inactive for most of the year. During the breeding season,
however, the male and the female reproductive organs increase greatly in size.
Materials:
 Pigeon
Dissecting tray
 Scalpel
 Scissors
 Forceps
 Dissecting pins
 Probe
Procedure:
External Anatomy
1. Identify the external features of the pigeon.
 Beak- the upper beak is the maxillary and the lower beak is the mandible.
Both
are covered by a horny sheath that grows continuously and is worn down with use.
 External Nares- these are the two nostrils and are covered by the fleshy cere
 Eye- each eye has lower and upper eyelids, beneath these is the nictitating
membrane or the third eye. The membrane is used to brush tears across the eyeball.
Diving birds use their clear nictitans as “contact lens” providing clarity of vision while
under water. This membrane is located in the anterior corner of the eye.
 Ear- External ear openings are located posterior to the eyes. Brush the feathers of
the ear coverts forward to find the external ear openings.
 Feet- study the skin on the feet. Note its texture and the presence of absence of
feathers. Look at the tops of the pigeon’s toes.
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Feathers
2. Place the pigeon ventral side up in a dissecting tray. Spread out one wing so that the various
types of feathers are visible.
3. Locate the primary feathers which are attached to the bones of the ‘fingers’ and the wrist.
4. Find the shorter secondary feathers which are attached to the ulna.
5. Identify the smaller scapular feathers, which grow from the shoulder. Primary, secondary,
and scapular feathers are all flight feathers and are covered by small, shingled covert feathers.
6. Locate the ulula feathers, which are attached to one of the bones of the ‘fingers’. These
feathers, which are similar to the slots on the leading edge of an airplane wing, allow for slower
flight.
7. Pull out one of the primary feathers and examine it. Locate the long, slender hollow shaft.
From the shaft, you will not that barbs extend outward at an angel of about 45 degrees. With
your fingers, gently pull apart the barbs. Notice that they are formed of still smaller barbules
with interlocking hooks. Examine the barbs and the barbules and draw and label the major
structures of the feather in the data section.
Oral Cavity
8. To examine the oral cavity, cut through the angle of the jaws with scissors and identify the
following part.
 Tongue- used for manipulating food, is narrow and sharply pointed
 Palatine Folds- Fleshy folds that extend from the lateral borders of the upper jaw to
the midline. Probe between the midline slit of the palatine fold to expose a dorsal
passage through which air passes from the nostrils to the glottis.
 Pharynx
 Glottis- opening to the larynx is a slitlike opening on a raised area just posterior to
the tongue
 Esophagus- extends from the pharynx to the stomach
Muscles
9. Place the pigeon on your dissection tray ventral side up.
10. Part the feathers mid-ventrally to expose the bare skin. By running your finger from
anterior to posterior between the now parted feathers you should be able to feel a bony ridge.
This is the keel that anchors the large flight muscles.
11. Carefully with your scalpel make a very shallow incision along the keel. You only want to cut
through the skin, not the muscle. Use the diagram below to carefully make the transverse
incisions.
12. Carefully peel the skin back revealing the muscles.
 Pectoralis-this large muscle originates on the furcula (wishbone) and keel. The
downward stroke of the wing is its primary action.
 Supracoracoideus- this muscle lies underneath the pectoralis. Its origin is the keel. It
is involved with the upward stroke of the wing.
 Biceps- the action of the biceps is flexing and rotating the forewing.
 Triceps- Extensions of the forewing is the action of the tricep.
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Internal Anatomy
13. To open the thoracic cavity, use your scissors to carefully cut through the sternum. Cut from
inferior to superior along both sides of the keel. Stop at the superior most portion of the rib
cage. Remove this part of the sternum, spread the ribs and cut them back toward their dorsal
attachments.
14. Remove the skin of the throat to reveal the crop, trachea and esophagus.
15. Identify the following structures
 Trachea- a tube reinforced with rings of cartilage (young birds) or bone (adult). It
conducts air from the oral cavity to the lungs.
 Esophagus- Dorsal to the trachea lies the esophagus, the muscular tube through
which food passes to begin digestion in the stomach. You may have to move the trachea
to one side to find the structure.
 Crop- The double sac or swelling of the esophagus used to store food prior to
reaching the stomach. In pigeons the crop is also the source of “pigeon milk” fatty
epithelial cells that are shed as a semi-liquid and consumed by the young.
 Stomach- Below the crop is the stomach which has two parts. The upper part is called
the proventriculus. In this part of the stomach, digestive enzymes secreted by gland
break down food that has passed into the stomach. The lower part of the stomach is the
gizzard which is the strong muscular part.
 Gizzard- the posterior portion of the stomach. Where seeds and grains are ground up.
Often the bird will swallow small stones to aid in this process.
 Liver- Divided into two lobes and makes bile
 Gall Bladder- The liver surrounds the gall bladder and stores and sends bile to the
intestine.
 Pancreas- An elongated organ found near the liver.
 Intestines- Primary organ of digestion and absorption of food.
 Caeca- Locate these two small blind pouches as you approach the terminal end of the
intestines. Some bacterial decomposition of fibrous food takes place here.
 Large Intestine- Posterior to the area where the Caeca attach is this short region of
large intestine that empties into the cloaca.
 Kidneys- Tri-lobed organs located dorsal to the lungs. Large in size.
 Testes (male)- Located ventral and anterior to the kidneys, these paired bean-shaped
organs vary in size related to the breeding season.
 Ovary (female)- Involved with egg production only the left side ovary develops. Look
for a cluster of berry-like structures of varying sizes, these are developing eggs.
 Heart- 4 chambered, using your scalpel, carefully make a lengthwise cut through the
heart starting at the lower lip and moving toward the anterior end. The cut should
separate the heart into a ventral part and dorsal part. You should now be able to see the
cambers of the bird’s heart. Sketch what the inside of the two parts look like in the data
section.
 Lungs- can be seen flattened against the body wall by retracting the digestive organs
to one side. Attached to the lungs are air sacs.
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Data:
1. Draw and label the feather.
2. Sketch the heart.
Analysis:
1. Does the bird have any teeth and explain how it grinds up food.
2. Why might you find small stones in the stomach and gizzard?
3. What body parts does the pigeon have to help it fly?
4. Which muscles help with downward and upward stroke of the pigeon’s flight?
5. What is the difference in function between the gizzard and the crop?
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6. Is the heart of the pigeon like that of a frog? Explain.
7. Match the pigeon body part with its function.
Grinds and mashes food ______________________
 Where acid and enzymes start to digest food __________________________
 Stores bile __________________
 Makes bile __________________
 Stores food waiting to be digested ______________________
 Ringed windpipe _____________________
 Receives sperm/eggs, urine and digestive waste ___________________
 Attachment for flight muscles _______________
 Attached to the lungs ____________________
 Absorption of food ______________________
 Cluster of berry like structures _________________
 Brings air to lungs ________________________
8. Describe 3 facts that are new about birds that you haven’t seen in any other animal so
far.
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