Ornithology Exam 2

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?

1. Pre-conditioning period
2. Conditioning phase
3. Stimulus presentation phase
4. 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?

1. Sclerotic ring
2. Dorsoventrally flattened
3. Pliable lens
4. Highly-vascularized pectin

What adaptations are seen in the owl eye?

1. More tubular
2. Larger lenses
3. 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

1. Carotid arteries inside vertebrae
2. Enlarged foramen of transverse process (w/air sac)
3. Collateral vessels for detour


1. 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?

1. Self-recognition
2. Episodic memory
3. Social learning


1. 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