Lecture 2 & 3 - Avian Anatomy And Physiology Flashcards
(195 cards)
1
Q
Define topography
A
The appearance of the animal - external structures
2
Q
How many species of birds are in the world?
A
About 8500
3
Q
Taxonomically, birds are placed in the class _______
A
Aves
4
Q
What is the primary distinguishing feature of birds?
A
Feathers
5
Q
How do birds birth their young
A
Lay eggs
Oviparous
6
Q
What are the only other species that flies besides birds?
A
Bats
7
Q
The dermis of birds is made of a thin flap of epithelial cells that produce keratin. What structures is this necessary for?
A
Outer sheath of break and claws
Feathers
8
Q
The dermis is a thicker, fibrous connective tissue layer. What are the two main responsibilities of the dermis?
A
Storage for fat
Movement of muscles via smooth muscles (heat regulation)
9
Q
True or false:
Birds have sweat glands
A
False
10
Q
What is the uropygial gland, what does it do?
A
The preen gland
Found on the dorsal surface at the base of the tail feathers
Secretes an oily fatty substance that waterproofs the feathers
Varies in size with species
Lacking in some species (parrots and flightless birds)
Birds put oil on their beak and rub it all over their feathers
11
Q
What do birds that do not have a preen gland often prefer rather than water baths?
A
Dust baths
12
Q
Describe the beak of birds, what determines their shape?
A
Derivative of a bird’s skin (keratin formation) it is covered in a horny keratin layer
Varies in hardness, flexibility and shape based on the function and what the bird eats
13
Q
True or false:
Bird beaks grow continuously
A
True
14
Q
What does it mean if a birds beak grows continuously?
A
Surfaces and foods to help maintain normal length must be provided
Trim and file the beak if needed
15
Q
What can a beak overgrowth indicate?
A
Internal problems
Nutrient problems
16
Q
Describe the claws of birds. How do they differ between species?
A
Horny sheath derived from specialized scales (end of each toe)
Grow continuously
Differ based on perching habits and how the procure food (hunting or not)
17
Q
“Quick” a bird’s nail
A
Cut too deep and hit the blood vessel within the nail
18
Q
True of false:
Feathers are living structures on the bird
A
False
They are non-living structures
19
Q
Describe feathers.
What are their 5 main functions?
A
Outgrowths of skin made of protein
1) Flight
2) Protection
3) Thermoregulation
4) Camouflage
5) Communication between birds
20
Q
Where do feathers have sensation?
A
At the base in the area of attachment
21
Q
What are the anatomical parts of a feather?
A
Quill/calamus
Rachis
Bards
Distal and proximal umbilicus
22
Q
Describe the anatomy of feathers
A
Quill/calamus: hollow tube below the fluffy part of the feather (no barbs)
Rachis: continuation of the quill with barbs attached
Bards: individual hair strands
Vane: a group of barbs held together by hooklets and barbules
Distal and proximal umbilicus: distal - hole at the end of barbs. proximal - hole at the end of quill
23
Q
Define contour feathers
A
Most visible feathers
Give shape to the bird
Most compact microstructure: quill, rachis, vane (barbs, barbules, hooklets)
Have a tight structure on the fluffy part of the feather - held together. Often contain the colour of the bird.
24
Q
Describe contour feathers
A
Most visible feathers
Give shape to the bird
Most compact microstructure: quill, rachis, vane (barbs, barbules, hooklets)
Have a tight structure on the fluffy part of the feather - held together. Often contain the colour of the bird.
25
Describe semi-plume feathers
Found under contour feathers (mainly on sides, necks, and back)
Provide insulation, flexibility and buoyancy in water birds
Central rachis with free barbs (no barbules or hooklets) (barbs not held together)
26
Describe down feathers
Soft, fluffy, located next to the skin
Function in insulation
No rachis, only a calamus with free barbs
27
Describe powder down feathers
Specialized type of down feather
Never stop growing
Disintegrate at the tip which creates a waxy powder that spreads on the plumage through preening (clean and waterproof bird)
Highly developed in birds without uropygial gland
28
Describe a filoplume feather
Sensory or decorative in function
Elongated rachis with barbs only at distal portion
29
Describe bristle feathers
Modified contour feathers
Serve as sense of touch
Location depends on species
Long, tapered rachis, few or no barbs at the base of the rachis
30
True or false:
| Feathers originate all over the body
False
Feathers overlap and are laid down in tracts with areas of bare skin in between
31
Describe apteria
Where feathers do not grow on birds (bare areas)
32
Describe molting
The process of replacing feathers
Occurs in species specific patterns (allows birds to continue on with life)
Generally a gradual process
Usually occurs symmetrically on the body
Only one or two major flight feathers at a time
33
When is the major molting time?
Fall
34
What is different about water fowl molting?
They lose all their feathers at once following the breeding season
35
Where do feathers grow from?
Papillae in feather tracts of the dermis
36
What pushes out old feathers?
A newly developing feather
37
What are feathers first covered in?
Emerges covered in periderm
Is removed by preening
38
What is the objective of wing clipping?
Clipping feathers so the bird cannot get lift and fly, while still being able to glide down from perches etc.
39
Describe how bird wings are clipped
Trim 5-7 flight feathers under the coverts
Trim outermost feathers OR leave 2 or more primary feathers intact
40
Why should blood feathers (immature feathers) not be clipped or the feathers on either side of them?
These will cause major bleeding when cut
Don't trim on either side to protect them from breaking
41
Where do primary flight feathers originate from?
The "hand" (metacarpus and digits)
42
Where do secondary flight feathers originate from?
Radius and ulna
43
Describe the major and minor coverts
The feathers that cover the starts of flight feathers
44
What do external parasites do to feathers?
Chew and consume parts of the feather vanes, creating weak points
45
Damage to feathers can also be due to?
Daily wear and tear
46
Describe a fault bar
A stress bar
Weakened area in the feather vane where barbs lack barbules
Feather is stressed during its growth when blood flow is disrupted
47
What is the most common stressor for birds?
Diet
48
Describe feather picking
Common in captive psittacines and imprinted raptors
Can be cause by boredom or disease (parasites, infection, toxins)
Over picking of the feathers
49
What is the main cause of feather picking in small birds?
Medical cause
50
What is the main cause of feather picking in large birds?
Behavioral issues
51
What cause of feather picking is harder to treat?
Behavioral
52
What are modifications of the musculoskeletal system of birds that allow for flight and walking?
Reduction in number of bones
Fusion of some bones to form plates (keel)
Reduction in bone density
Loss of internal bone matrix (hollow, air filled spaces)
53
Describe the axial vs appendicular skeleton
Axial: skull, vertebrae, sternum (framework)
Appendicular: wings, shoulders, legs, pelvis (locomotion)
54
Describe the skull of a bird
The jaw bone extends into the keratinized bill
Large eye sockets bordered by sclerotic ring
Very small portion of skull devoted to olfactory system
55
True or false:
| Birds have a greater number of cervical vertebrae
True
56
Describe the thoracic vertebrae of birds
Rigid to provide strong support for ribcage
Have the uncinate process that overlap adjoining ribs
57
Describe the lumbar and sacral vertebrae of birds.
Fused vertebrae form bony plate to support legs (synsacrum)
58
Describe the coccygeal vertebrae of birds
First few mobile to allow movement of tail feathers
Pygostyle: fused bony structure that supports tail feathers
59
True or false:
| Lumbar and thoracic vertebrae do not move
True
60
Describe the sternum of birds
Large and concave
Protects the chest
Acts as a place of origin for flight muscles (keel) (pectoral muscles are the flight muscles)
61
Describe the three complex bones of the shoulder
Coracoid: prevents the collapse of the whole structure from the force needed to push wings together
Scapula
Clavicle (wishbone): fused clavicles are called a furcula
62
Ture or false:
| There is more force needed for the down stroke during flight
True
63
Describe the movement of the shoulder
Allows several planes of rotation
64
Wing muscles attach at the
Pectoral crest of the humerus
65
The humerus is longer in birds that?
Glid and soar
66
Describe the movement of the elbow
Only allows movement parallel to the wing
67
What is the patagium (propatagium)
The web of skin that extends from shoulder to wrist
Assists in aerodynamics
68
What are the alula bones
First digit that originates from the wrist
Carries the alula feathers (steering) for fine control
69
Describe the metacarpal bones
Fused to form major and minor metacarpals
2 in total
Join with digits 2,3,4
Help support primary flight feathers
70
Describe the pelvis of birds
3 paired bones join where leg attaches to body (ileum, ischium, pubis)
Distal ends of pubis not fused: provide room to facilitate egg laying
71
Describe the legs of birds
Femur is directed forward to the knee
Some tarsal bones are fused with the tibia forming the tibiotarsus
Some tarsal bones are fused with the metatarsals to form the tarsometatarsus
Single bone of the "hock" spans from the ankle to the digits
72
Describe the feet of birds
A metatarsal pad on the bottom of the foot surrounded by 2, 3, or 4 digits
3rd toes is usually the longest
73
Describe anisodactyl, give some examples of these
One toe faces to rear, other three face forward
Galliforms, raptors, song birds
74
Describe zygodactyl, give an example
2nd and 3rd toes face forward
1st and 4th toes face backwards
Parrots
75
Describe bumble foot
Infection of the feet, usually from a staph infection
Causes severe swelling, ulceration and discomfort
Linked to perches that are all the same size, too rough or not rough enough, or long claws
Change the perches and treat with antibiotics and preparation H (topical)
76
Why is it difficult to treat feet problems in birds
Birds are always on their feet, walking in feces especially
Infections spread fast since there is little tissue surrounding and very close to bone
77
Many muscles of birds are placed
Ventrally, near the center of gravity
78
What are white fibers in muscles
Thick
Low blood supply
Little myoglobin
Uses stores of glycogen
Found in flight muscles of short distance fliers
Exhaust quickly
"White meat" in bird breasts
Sprinting, short bursts of flight
79
What are red fibers in muscle
```
Thin
Large blood supply
Fat
Lots of myoglobin
Mitochondria
```
Found in flight muscles of long distance fibers
Dark meat (legs)
Marathon runners, flying for long distances
80
Describe what muscle fibers birds have depends on
Depends on lifestyle of birds (fliers vs walkers)
Some muscles have one or the other or a combination of both
81
Describe the movement of wings in flight and the muscles involved
Both muscles found on the chest responsible for raising and depressing the wing
The pectoralis muscle is larger and more superficial, flexion causes the wing span to close (down stroke)
The supracoracoideus is smaller and deeper, flexion causes the humerus to move and the wing span opens (up stroke)
82
What is the muscle of choice for IM injections in birds
The pectoralis muscle
83
Describe the muscles of the legs in birds, how are the toes controlled?
Primarily located over the femur
Control movement of the toes through long tendons
84
What is the perching reflex
Claws close as the leg flexes
Allows bird to remain perched while sleeping (won't let go or fall off)
85
How can the perching reflex be used when clipping nails?
Extend the leg to open the claws
86
Describe the muscles of the head and neck
Extent of the jaw muscles vary depending on diet (strength needed to eat specific foods - hard nuts vs seeds)
Neck muscles allow movement in different directions
87
Describe the hatching muscle and the "egg tooth"
Aid in the newborn chicks to break through their shell
Hatching muscle is on the back of the neck to give power when breaking shell (atrophy after bird)
Egg tooth is a small cornified structure on the beak to aid in breaking
88
Describe the brain of birds, what differs compared to mammals?
Large in proportion to its body
Location of different centers are similar to mammals, but have a large center for vision and hearing, and a small center for taste, touch, and smell
89
Describe the vision of birds
Highly developed
Large portion of the skull is made for housing and protecting the eyes (shape of the eye depends on the orbits)
Has limited movements in some species (most have to move their entire head rather than their eyes - owls)
90
Describe the shape of diurnal birds' eyes
Round or relatively flat eyes
91
Describe the shape of nocturnal birds' eyes
Tubular (elongated)
92
What are the 3 main divisions of the anatomy of the eye
Fibrous tunic
Uveal tunic
Neural tunic
93
What does the fibrous tunic contain? What are some specialized structures in this area in birds?
Sclera and cornea
Birds have a sclerotic ring that reinforces the sclera
Nictitating membrane (third eyelid)
94
Describe what would be different about a diving bird's nictitating membrane
May have a clear center so they can see under water - protects the glute
95
What does the uveal tunic contain? What is the main difference here in birds compared to mammals?
Choroid, iris, ciliary muscles
Muscles in the iris are under VOLUNTARY control
96
If the muscles in the iris are under voluntary control, what does this mean for the pupillary light reflex test?
In birds this is NOT considered a reflex.
When a light is put into the eyes, the bird is literally choosing to constrict their iris.
97
What does the neural tunic contain?
retina
98
Describe the vascular pectin in the eye
Highly vascular comb-like structure that projects into the vitreous humour from the point of the optic disc.
Provides oxygen and nutrients to the eye and removes waste
Can easily hemorrhage with head trauma and will see bleeding from the eyes
Present bc have a reduced number of blood vessels in the retina to allow more photoreceptors (rods/cones)
99
True or false:
| Nocturnal species have more cones than rods
False
They have more rods than cones
Rods: low light vision
Cones: colour vision
100
Describe how birds have a higher level of visual acuity
Reduced number of blood vessels in the retina to allow more photoreceptors
Each cone has a single connection to a nerve fiber
Oil droplet in each cone increases colour reception
Wide spectrum of light wavelengths are able to be perceived
101
Some species have a temporal fovea in the eye, what does this do?
Increases binocular vision
102
Describe the ears of birds. What are some main differences?
Located on the sides of the head, behind and slightly below the eyes
Do not have much of an external structure
Middle ear only contains ONE bone (mammals have 3) called Columella
103
What makes the hearing of nocturnal owls so highly developed?
Contain a operculum: a muscularly controlled flap of skin in the ear that opens and closes to allow focusing of the ear
Also have asymmetrical ear openings to allow them to pinpoint where sounds are coming from
Large eardrums, columellae and cochlea
Well developed acoustic center in the hindbrain
104
Describe the tasting ability of birds
Poor sense of taste
Very few taste buds scattered on the sides of the tongue and soft palate
Levels of sensitivity and thresholds to taste vary in species (most can only differentiate types of taste - bitter, sweet, salty)
105
Describe the sense of smell in birds
Highly variable in species depending on diet (hunting birds have better sense of smell)
106
True or false:
| If you pick up a baby bird from its nest, the mother will abandon it because it smells like humans
False
| This is a myth, return the bird as close to the nest as possible
107
Describe the two main nerve endings for sense of touch in birds
Grandry's Corpuscle: nerve endings prevalent on tongue, palates and bills of birds
Herbst Corpuscle: nerve endings present on cloaca, legs, wings, uropygial gland and feather bases
108
What is the main difference of the endocrine system of birds?
7 major glands plus the pancreas all function similar to mammals
The Bursa of Fabricus is the initial site of B lymphocyte production (rather than in bone marrow in mammals)
109
Because birds have such a fast metabolism, what does this mean for their diet?
They require large amounts of food for the high energy demand
110
Beaks or birds vary with
Diet
111
The mouth of birds is similar to mammals, containing hard and soft palates, tongue, salivary glands, and taste buds. What is the main difference in some birds?
Some species have a soft palate that enlarges into a pouch for temporary food storage (pelicans)
112
What is the main difference of the hard palate in birds, what is it used to evaluate?
Hard palate has an opening that communicated with the nasal cavity (choanal slit)
Used to evaluate papillae for nutritional deficiencies
113
Describe how the tongue varies with species
May be slightly muscular in some species
May have very few muscles and is moved by muscles of the jaw apparatus in other species
114
Describe the main difference in the esophagus of some species of birds
Contains a crop
An expansion of the esophagus over the interclavicular space
This is a place for storage, lubrication, passage, and potential mechanical breakdown of food
Very little digestion occurs here
115
Describe the crop in pigeons and doves at breeding time
Mucosal lining can break down and slough off to form "pigeon milk"
116
Describe the crop in insect eating birds
Heavy epithelium protects the crops when insects are swallowed alive
117
Describe the stomach of birds
Two separated compartments
Proventriculus: glandular compartment - chemical digestion begins here with pepsin and HCL
Ventriculus /Gizzard: muscular stomach - striated muscles grind food (mechanical) ingested grit aids in grinding food here (rocks)
118
What is the pellet
Ingested food ground into a pellet in the ventriculus get regurgitated
In birds of prey the pellet is mainly formed of bone, fur, etc. - parts that couldn't be digested
119
Describe the liver of bird
Bilobed - right lobe is larger than the left
120
Describe the pancreas in birds
Relatively large especially in fish and grain eaters
Rests in loop of the duodenum
Endocrine portion occupies more tissue mass than in mammals
121
Describe the duodenum in birds
Main organ for digestion and absorption of nutrients
Varies in length and thickness depending on diet
122
Describe the ceca in birds
Paired sacs at the junction of the small and large intestines in some species
Role in water reabsorption and in bacterial fermentation of cellulose
Contents excreted independent of fecal matter
123
Describe the large intestine in birds
Major role in reabsorption of water and minerals
124
Describe the cloaca
The end of the digestive tract
Common exit for the digestive, urinary, and reproductive systems
125
Describe the 3 sections of the cloaca
Coprodeum: receives excrement from the intestines
Urodeum: receives discharge from the kidneys and genital tracts
Proctodeum: stores excrement and eliminates it
All 3 things get combined/stored before excretion
126
Describe the vent
Muscular anus that expels waste products (mute)
127
Waste excreted by birds is called
Mute
128
Describe mute
Combination of feces (dark) and urine (liquid) with white powdery urate around it
Varies with diet
129
How can mute be used to assess health?
Can indicate disease based on colour
Green mute can indicate chlamydial infection (zoonotic), internal parasites or liver disease
130
Why should owners be familiar with the appearance of mute in their birds when they come into clinic?
Because stress can change how the mute looks when in clinic
Encourage to take a photo
131
Why can bird not technically vomit?
They have no diaphragm
132
Describe tube feeding birds
Trachea is a small hole found more rostral in the throat, the esophagus is more caudal
Watch the back of the throat for regurgitation/over flow
- indicates you put too much food in (risk of aspiration since trachea is so close and there is no real epiglottis present)
133
Describe the heart and where it lies in birds
4 chambered, right side is smaller and less muscular
Lies in the cranial portion of the thoracoabdominal space (called this since there's no diaphragm that separates the cavities)
134
Why do birds have large pectoral and brachial arteries?
To meet the specific demands of these highly muscular portions of the body (need a lot for flight)
135
Describe the air sacs of birds
9 thin walled, high vascular membranes
Connect to the bronchi - some extend into bone cavity
```
Functions:
Air reservoirs
Provide warmth and moisture to air
Thermoregulation
Buoyancy
```
136
Describe the countercurrent heat exchange system in the legs of birds
A system of heat exchange in lower extremities through a network of arteries and veins placed closely together
Heats up blood from the extremities before reaching the core to prevent hypothermia, and colder temperatures are sent with arteries back to the extremities
Does not constantly occur (like in summer) - has a sphincter that opens/closes depending on temperature
137
Why should the renal portal system in birds be taken into consideration before injecting medications?
Would want to do it in the upper body so the medication can spread systemically before it gets filtered out by the kidneys
138
Since birds have a fast metabolism, what does this mean for heart rate and blood flow?
Fast heart rate
| More rapid blood flow
139
Electrodes used in electrocardiography are placed on
Wings and legs
140
Functions of blood
Carry nutrients, oxygen and hormones
Carry metabolic wastes to lungs/kidneys
Control/prevent disease
Regulate body temperature
141
What is the main difference of erythrocytes and thrombocytes in birds compared to mammals
They are nucleated
142
What are neutrophils called in birds?
Heterophils
143
Describe erythrocytes in birds
Oval, nucleated and larger than mammals
Formed in bone marrow in adults or in spleen/liver of some species
Posses hemoglobin
Total number dependent on age, sex, diet, and time of year
144
Describe heterophils in birds
(Neutrophils)
Phagocytes
Round with rod shaped red/orange granules
Bilobed nucleus with clumped chromatin
145
Describe thrombocytes in birds
Birds do not have platelets, they have THROMBOCYTES
Nucleated cells that act as platelets
Smaller than RBCs with large, round/oval nucleus
Produced by bone marrow in adult birds
146
Describe the syrinx
The voice box
Enlargement of the trachea above the sternum
Contains muscles, air sacs, and vibrating membranes
147
Respiratory rate increases with?
Activity, heat, flying high
148
Why do birds have such an extensive respiratory system?
High demand due to fast metabolism and high energy levels (fliers)
Also aid in buoyancy during flight
149
Describe the trachea of birds
Longer in comparison to body than mammals
Provide moisture and heating of inhaled air and aids in sound production
Have cartilaginous rings that surround the entire structure (not C shaped)
May be coiled in some species
150
Vocalization complexity depends on
The number of muscles present in the syrinx
151
Describe the bronchi of birds
Trachea bifurcates into 2 bronchi
```
These further divide:
Mesobronchi: in the lung
Secondary bronchi: ventrobronchi
Parabronchi
Air capillaries (site of gas exchange)
```
152
Describe the lungs in birds
```
Small and inelastic (do not expand/contract)
High vascular (bright red)
```
Attached to the thoracic vertebrae and ribs
Connect via projections into the bone that put air into the hollow spaces for buoyancy
153
Describe the renal portal system of birds
Blood vessels from the legs/lower body, returning to the heart is shunted to the kidneys to get filtered before returning to the heart
154
What is different about a birds trachea? What does this mean for restraint?
Have cartilaginous rings that surround the entire structure
Restrain mainly around neck since breath occurs with the chest cavity movement
155
Describe airflow in birds lungs
2 inspirations and 2 expirations are required to transport one breath of air through the entire system
Path of one breath/air pocket: 1st breath in, goes into posterior air sacs
1st breath out goes into lungs
2nd breath in goes into anterior air sacs
2nd breath out - air leaves
156
If birds have no diaphragm, how do they breathe?
A whole body process driven by the expansion of the chest cavity/ ribs
157
True or false:
| There is no mixing of inspired and expired air within birds
True
158
Due to their very sufficient respiratory system, what does this mean for inhaled chemicals?
Very rapid response and increased sensitivity to inhaled anesthetics
Very sensitive to poisonous gasses or inhaled irritants
Ex. Teflon pans can cause respiratory distress or death
Ex. Canaries used in coal mines - would die due to poisonous gasses before humans did - alert system
159
Describe the respiratory rate in birds
Varies with species, activity level, age, sex, time of day, outdoor temp
Smaller birds breathe faster
Birds in flight have higher heart rate
Respiratory rate is generally very fast and very high so not often used as a diagnostic tool
160
True or false:
| Intubation of birds is extremely easy
True
| Trachea is very easily visible
161
Describe how birds thermoregulate
Birds do not have sweat glands
Most heat is eliminated through respiration (water evaporated through respiratory system helps cool down)
Can increase this rate by panting or fluttering the upper throat patch with an open beak
162
Why is panting dangerous in birds?
Often indicated stress or over heating
Birds exist at a higher temperature compared to mammals, this leaves very little room for temperature changes before proteins begin to denature etc.
163
What are some other methods of decreasing temperatures in birds
Bathing
Decrease activity
Some species defecate on their legs to increase evaporative cooling
Adjusting feather position ( proofing to warm) open up bare patches to cool
164
Other methods of raising body temperature in birds
Perching on one leg to minimize skin exposure
Tucking head and beak under feather on back
Shivering
Seeking shelter
Some species (humming birds) can enter a temporary night time torpor (state of inactivity) to conserve heat
Countercurrent heat exchange in limbs
165
Describe the urogenital system
The urinary and reproductive system in birds
166
True or false:
| Female birds only have one ovary on the left side
True
167
Describe the salt gland
Many marine birds have
Located above each eye and drain into nostrils
Secrete large amounts of sodium chloride (salt)
Helps maintain ideal osmotic conditions in the body while living and feeding in a high salt environment
168
Describe the kidneys in birds
| What are the differences compared to mammals?
Large paired organ, 3 lobed, lie flush with the back bone
Renal portal system filters blood from lower body (controlled by a valve)
Similar in function to mammals but:
1) no renal pelvis
2) two types of nephrons: looped (similar to mammalian nephrons) and unlooped (similar to reptilian nephrons
169
True or false:
| Birds do not have a urinary bladder
True
| Excrement from kidneys get collected in the urodeum of the cloaca
170
Describe the urine composition of birds
Different from mammals:
Higher uric acid concentration (urea is predominant in mammals)
Uric acid eliminated as a white powder in combination with fecal material (usually green or brown with a ring of white around it (urate))
171
Why is the different urine composition of birds more advantageous?
More efficient way to get rid of nitrogenous waste:
1) less water loss
2) allows embryo to store large amounts of nitrogenous waste with the confines of the shell without dying (wouldn't be possible with urea since urea is toxic and uric acid is not)
172
Breeding season in birds is often stimulated by ______. What does this affect in the bird?
Increasing day length in parts of the world where seasons are more pronounced
Affects hypothalamus and causes an increased secretion of gonadotrophic hormones
173
Non-breeding animals have very small gonads, which increase in size when?
Breeding season approaches
174
How are most birds differentiated by sex
Most species have very little sexual dimorphism, so the only way to tell sexes apart is by DNA testing (blood test)
175
Describe the testes and where sperm is stored in birds
Testes are bean shaped and located internally
Sperm are stored in a pouch
Seminal vesicle (temp is 4 degrees cooler than body temp) located at the terminal end of the vas deferens
176
The vas deferens carries sperm to the
Seminal vesicle and cloaca
177
Describe copulation for males
Behavior stimulated by androgens (from leydig/interstitial cells in the testes)
Some species (galliforms, ratites, and ducks) have a grooved penis that assists in sperm transfer
Other species simply bring cloaca together for copulation
178
True or false:
| Basic ovarian follicles development and ovulation in birds is similar to mammals
True
179
Transfer of the ova into the oviduct is similar in birds to mammals, what differs as the egg passes through the oviduct and uterus?
The eggs get surrounded by layers of albumin (egg white) the shell membrane, shell and pigments
This means the ova is the egg yolk in an egg
180
Birth of the eggs is through the
Cloaca
181
Describe the 5 sections of the genital tract in females and how they contribute to development of the egg.
1) infundibulum: catches the ovum when released from the ovary, fertilization occurs here
2) magnum: secretes albumin
3) isthmus: secretes inner and outer shell membranes onto fertilized ova
4) uterus (shell gland): secrets thin water albumin, the shell and pigmentation, the eggs spend most time here to form egg (uses tons of calcium)
5) vagina: secretes mucus for egg laying and stores sperm for hours to days
182
Describe egg binding/ egg bound birds and why it is considered a medical emergency
When the egg fails to pass from the uterus to the cloaca
Since the bird only has one opening for the reproductive, urinary, and digestive systems, when an egg is blocking here it prevents urination and defecation (can die very quickly)
Signs: depression, stop eating, penguin-like gait
183
How is an egg bound bird treated?
Anti-inflammatories, topicals, baths, calcium supplements, manual manipulation or surgically by collapsing the egg with a needle through the cloaca
184
How is egg binding prevented
Avoid obesity
Watch for vent picking and separate affected birds
Ensure adequate calcium in diet
185
Define clutch
The number of eggs laid and incubated
Varies in species (1-20)
186
Describe determinate layers
Total number in clutch predetermined by number of follicles developing in the ovary
187
What are indeterminate layers (most birds)
Eggs are continuously produced until a set number is reached in the nest
If eggs are removed the bird will continue to lay indefinitely
The signal to stop includes visual tactile and hormonal influences indicating a full clutch (birds literally count)
188
Why are indeterminate layers beneficial with endangered species
Will remove eggs and incubate artificially so the bird will continue laying
189
Eggs can be laid everyday, every other day, or every 4-5 days
Some species incubate all at once or as eggs are laid
What can this result in
Chicks may all hatch and develop at varying time
Or chicks may all hatch and develop synchronously
190
How do birds incubate their eggs
Sitting on the eggs/nest to keep eggs at a certain temperature in order to develop (need to be kept warm and humid)
Females have a "brood patch" - featherless patch on belly where skin folds, thickening and blood circulation create a heat pad for eggs
Time for incubation varies with species (longer for larger birds)
Budgies: 18 days
191
What do the 4 classifications of chicks depend on?
Feather coverage
Open or closed eyes
Mobility
192
Describe precocial chicks
| Give an example
Ducks and geese
Downey feathers
Open eyes
Mobile
193
Describe semiprecocial chicks
| Give an example
Gulls and terns
Downey feathers
Open eyes
May be mobile but remain in nest
Dependent on parents
194
Describe semialtricial chicks
| Give an example
Hawks and owls
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Downey feathers
Open eyes (hawks)
Closed eyes (owls)
Not mobile
Confined to nest for care
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195
Describe altricial chicks
| Give an example
Song birds
Little to no feathers
Closed eyes
Not mobile
