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What makes hoatzin digestion so special?
They’re true ruminants.
How do hoatzins digest their food?
Through combination of fermentation, mechanical digestion (contraction of crop and esophagus), and symbiotic bacteria
What is the function of the cloaca?
It collects fecal material from the intestines before ejection through the vent
What is the basic structure of the avian stomach?
Esophagus → Proventriculus → Gizzard
What does the proventriculus do?
Produces mucus
What does the gizzard do?
Muscular section that acts as “teeth”
Where are birdsongs primarily created?
In syrinx
Where is the syrinx located?
At the bifurcation of the trachea
What affects how sound is produced in a bird?
Its species and how it is able to modify airflow
External Tympaniform Membrane Function
Vibrate like a drum to produce soundS
Semilunar Membrane Function
May act with external muscles to constrict bronchi openings, producing sound as air rushes form lungs under pressure
Left and Right Tympaniform Membrane Function
May be constricted to produce a double note
What happens in the first inhalation?
Breath flows down the trachea (passing through syrinx) into either bronchus. Then the bronchus brings the air to the lung, and most air is passed completely through the lungs to posterior air sacs. [Passes lungs into posterior air sacs]
What happens in the first exhalation?
The abdomen contracts, forcing air from the abdominal sacs into the lungs. Air passes through the parabronchi in lungs, and gas exchange occurs.
What happens in the second inhalation?
Air in the lungs is driven out and this stale air passes into the anterior air sacs
What happens in the second exhalation?
Anterior air sacs contract, which drives air out into trachea and out through nostrils
How is the furcula important for respiration?
As it expands and contracts during flight, it causes expansion and contraction of the interclavicular air sac. This pumps air through the respiratory system [bellows]
How important is olfaction to turkey vultures?
It is their primary sense to locate food (reflected by large olfactory lobes). Those with keen senses of smell are able to exploit scavenging niche unavailable to those that hunt solely by sight.
What are some primary findings of the crow paper?
Crows use multiple learning opportunities + social learning
How did the research on crows show they used social learning?
They didn’t have to physically witness a dead crow to fear the area they knew it to be, as they watched other crows and perceived the message of danger.Wh
What were the four phases of the crow research?
Pre-conditioning period
Conditioning phase
Stimulus presentation phase
Post-exposure phase
What were the primary findings of the Coot Survival Advantage paper?
Eggs hatch asynchronously, with the more brightly-colored chicks hatching later. This allows the parents to pay special attention to these weaker chicks after an initial culling period. Therefore, there is a survival advantage to being brightly colored beyond mating
What were the primary findings of the Coot Hatch Order paper?
American coots can recognize and reject parasitic chicks through learned cues. Chicks that hatch on the first day (usually native) are used as referents for learning recognition cues that can be applied to later-hatching chicks in the same brood
How many times has flight evolved?
4
In what order did the four groups evolve flight?
Winged insects → Pterosaurs → Birds → Bats
What are the three major types of flight?
Flapping, hovering, and soaring
Which part of flapping is more forceful, and why?
The downstroke, because this is when lift is generated
Which part of flapping is less forceful, and why?
The upstroke, as it is more important for propulsion
What is hovering?
When birds in flight lack propulsion-- they simply remain in place
What is static soaring?
Gliding
What are the three types of soaring?
Thermal, slope, and dynamic
Which type of flight requires the most energy?
Hovering
Which type of flight requires the least energy?
Soaring
Thermal Soaring
Birds use rising warm air currents to soar (does require random flapping, but energetically free)
Slope Soaring
Birds use wind deflected off topographic features to drive flight
Dynamic Soaring
Birds use rising air currents above waves (as air moves faster farther up), and a sinusoidal flight pattern capitalizes on changes in wind speed as birds rise
How may the K-T Extinction have contributed to the evolution of flightless birds?
Flying ancestors distributed across the world, but the extinction opened niche space for large, flightless birds
Why have diving birds primarily evolved flightlessness?
Diving requires dense bones and small wings, and both features would disable flight.
What species is able to dive and fly?
Guillemot
What are the three general adaptations of the bird skeleton?
Rigidity, reduction and redistribution of mass, and limb modification
Specific example of rigidity
Fused vertebrae in backbone to create support for flight
Specific example of reduction and redistribution of mass
Ventral side of bird is heavier than dorsal to aid in flight
Specific example of limb modification
Digits of forelimb lack many phalanxes
Which region of the bird skeleton is very flexible?
Neck
Why is a bird’s neck so flexible?
It has a pivot point (joint between 6th and 7th cervical vertebrae)
Other weight-reducing features of birds
Small lungs, pneumatic bones, beak, lack of fat storage, etc.
What is the function of the nasal conchae?
Humidifies air, filters air, and dissipates heat
How is the placement of breast muscle unique in birds?
It features two antagonists in the same locationH
How do birds raise the humerus when their breast muscles are located ventrally?
Supracoracoideus tendon contracts as the pectoralis pulls dow
What is the origin of the pectoralis muscle?
Carina
What is the insertion of the pectoralis muscle?
Humerus
What is the origin of the supracoracoideus muscle?
Sternum
What is the insertion of the supracoracoideus muscle?
Scapula
Air sacs occupy ___% of the thorax and abdomen
~15%
All air sacs are paired except for the ___
Interclavicular air sac
How many breaths are needed for a single mass of air to pass through the respiratory system?
Two breaths
What is negative pressure breathing?
Inhaling causes diaphragm and muscles between ribs to contract, which creates negative pressure that draws air into the lungs
Do birds use negative pressure breathing?
NO
How does the skeletal system alter volume if respiratory system?
Sternal and rib positions (along with furcula) create changes in available air space
Mammal respiratory system
Blind sacs with common entrance and exit points → Bidirectional air flow (results in stale air)
Avian respiratory system
Parabronchi tubes have separate entrance and exit points, which allows for efficient unidirectional air flow
Structure of avian heart
Birds have four-chambered hearts (two atria and two ventricles)
What does the left side of the avian heart do?
Pumps blood to the body
What does the right side of the avian heart do?
Pumps blood to the lungs
Why do avian hearts need to beat faster than reptilian and mammalian hearts?
Birds have much higher energy demands due to flight (as oxygenated blood is required to move at a faster rate)
Birds consume ___ times more energy than similarly-sized non-avian reptiles
20-30!
Compare cerebellum size in avian vs. mammalian brains
Avian brain has larger cerebellum
Gray Matter
Cell bodies (neurons)
White Matter
Axons
Compare organization in avian vs. mammalian brains
Avian brains are organized with grey matter found throughout the brain, whereas mammalian brains have grey matter pushed towards outer layer (think cities on east and west coasts connected by highways)
Do birds have a prefrontal cortex?
No, but they have an equivalent structure
What is the equivalent structure to the prefrontal cortex?
Caudolateral nidopallium
Compare pallial and striatal elements in avian vs. mammalian brains
Birds have pretty solid pallial and striatal elements (layers are thinner and more separated in mammals)
Compare information processing speed in avian vs. mammalian brains
Birds process information at a much higher rate
Compare neuron concentration in avian vs. mammalian brains
Birds usually have 2 times more neurons compared to non-avian brains of the same massW
Why did early scientists assume birds were unintelligent?
Lack of forebrain gyrification
Are there multiple ways to wire an intelligent brain?
Yes.
What is in charge of spatial memory?
Hippocampus
What brain structure is especially developed in food-caching species?
Hippocampus
Hippocampal Neurogenesis
Hippocampus is able to change its size throughout the year (grows when food is scarce, as it becomes more important to remember cache locations)
Which sense is the most developed in birds?
Vision
Why is vision the most developed sense in birds?
They need to be able to see exceptionally clearly when flying and hunting
How does the avian eye differ from mammals?
Sclerotic ring
Dorsoventrally flattened
Pliable lens
Highly-vascularized pectin
What adaptations are seen in the owl eye?
More tubular
Larger lenses
Enlarged sclerotic ring
What is the consequence of immobile eyes?
Necessary increase in neck rotation
How are the carotid arteries adapted in owls?
Located inside body of cervical vertebrae
How is the foramen of transverse processes adapted in owls?
Enlarged and contains air sac
What is the function of collateral vessels in owls?
Provide detours around constricted arteries
What do contractile reservoirs do?
Store blood and are able to send it to brain if needed
List of adaptations for owl neck rotation
Carotid arteries inside vertebrae
Enlarged foramen of transverse process (w/air sac)
Collateral vessels for detour
Contractile reservoirs store blood
Spectral Colors
Found within visible light spectrum, produced by single wavelengths
Non-spectral Colors
Produced by multiple wavelengths
How do we know corvids are smart?
Self-recognition
Episodic memory
Social learning
Tool use
Self-Recognition
Associated with high intelligence; corvids look in the mirror, see a colored dot on themselves, and try to wipe it off (normally animals would try to attack “rival” in mirror)
Episodic Memory
Ability to recall events at a specific place or time
Episodic Memory in Corvids
Scrub Jays, when provided with food in sight of other birds, will hide out of sight to protect their supply. If other birds are even within earshot, they will preferentially hide their food in quieter materials
Social Learning
Gaining new knowledge by observing and imitating others
What were some findings of Dr. Pepperberg’s work?
Birds understand and can communicate complex concepts such as analogies, numbers, colors, and shapes. Parrots are able to understand the vocalizations they create
How was the bird IQ index calculated?
Through examination of innovation in capturing/discovering food
What are some of the most intelligent birds?
Crows, rooks, jays, ravens, falcons, hawks, woodpeckers, and herons
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