Ornithology Lecture Exam 1

What are the key characteristics of birds?

Feathers, flight capability, endothermy, high metabolism, lightweight skeleton.

What evidence supports that birds evolved from dinosaurs?

Fossils like Archaeopteryx show transitional features between theropod dinosaurs and modern birds.

What are the major taxonomic groups of birds?

Passeriformes (songbirds), Accipitriformes (hawks), Strigiformes (owls), Anseriformes (ducks), among others.

How do birds' skeletal structures adapt for flight?

Lightweight bones, fused vertebrae, keeled sternum for muscle attachment.

How does the avian respiratory system function efficiently?

Air sacs allow unidirectional airflow, providing continuous oxygen supply.

Give an example of specialized digestive adaptations in birds.

Hummingbirds (Archilochus colubris) have long tongues to extract nectar efficiently.

What are the main types of feathers and their functions?

Contour feathers (aerodynamics), down feathers (insulation), filoplumes (sensory function).

What is the purpose of molting?

Replacing worn-out feathers, seasonal color changes (e.g., American goldfinch Spinus tristis changing to bright yellow in summer).

What are the four forces involved in bird flight?

Lift, thrust, drag, and gravity.

How does wing shape affect flight style? (Use an example)

A: Albatrosses (Diomedea exulans) have long, narrow wings for gliding; falcons (Falco peregrinus) have pointed wings for high-speed dives.

How is avian vision adapted for survival?

Birds have high-resolution vision, UV sensitivity (e.g., kestrels Falco tinnunculus detect vole urine trails in UV light).

What are the primary reasons birds migrate?

Seasonal food availability, breeding conditions, climate adaptation.

What species are known for long migrations?

Arctic terns (Sterna paradisaea) migrate from the Arctic to the Antarctic (~44,000 miles annually).

What are the common mating systems in birds?

Monogamy (e.g., bald eagles Haliaeetus leucocephalus), polygamy (e.g., red-winged blackbirds Agelaius phoeniceus), lekking (e.g., sage grouse Centrocercus urophasianus).

What is the difference between altricial and precocial chicks?

Altricial chicks (e.g., robins Turdus migratorius) hatch helpless, while precocial chicks (e.g., ducks Anas platyrhynchos) hatch more developed.

What are the main types of bird diets?

Herbivorous (parrots Amazona), carnivorous (owls Strix), omnivorous (crows Corvus).

Give an example of cooperative foraging

What are key transitional fossils in bird evolution?

What are key transitional fossils in bird evolution?

Confuciusornis had primitive feathers but lacked a modern beak.

What are the major evolutionary traits linking birds to dinosaurs?

Hollow bones, three-fingered hands, wishbones.

How do birds contribute to ecosystems?

Pollination (e.g., sunbirds Nectariniidae), seed dispersal (e.g., toucans Ramphastos), pest control (e.g., barn owls Tyto alba).

What conservation efforts protect migratory birds?

Migratory Bird Treaty Act, bird sanctuaries, habitat restoration.

What are the benefits of living in groups?

Predator detection, cooperative hunting, increased mating success.

Give an example of cooperative breeding in birds

Florida scrub-jays (Aphelocoma coerulescens) help relatives raise young.

How have birds been significant in human culture?

Domestication of chickens (Gallus gallus domesticus), messenger pigeons (Columba livia domestica)

Describe the jaw structure difference between birds, reptiles, and mammals

The reptilian and avian jaw have 5 fused bones while the mammalian jaw only has 1.

What are occipital condyles for? How many are found in birds?

They enable the skull to articulate with the vertebral column; birds and reptiles have 1, while mammals have 2

Describe the middle ear bone structure difference between birds and mammals

The avian ear has 1 ossicle columella (stapes) while the mammal ear has 3 ossicles (stapes, incus, malleus)

What are the shared characteristics between birds and reptiles egg structure?

• structures

• membranes

• egg tooth

Bird eggs are harder than reptile eggs due to more calcium being deposited

What are the 2 major hypotheses with respect to the origin of birds?

1) Thecodont: That birds evolved early, before dinosaurs, and from a stem group (not monophyletic!) of reptiles called thecodonts

2) Theropod: Or that birds evolved later from small theropod dinosaurs

What is an example of evidence that supports the THEROPOD hypothesis?

Recent fossil discovery of a troodontid fossil (Troodon) from Montana suggests that these more lightly built oviraptoirds brooded their eggs by sitting directly on top of them, rather than within a space circumscribed by the clutch.

What is an example of evidence against the THEROPOD hypothesis?

There is an inconsistency of arguing that birds evolved from organisms that lived many millions of years after the origin of birds took place

What is Morse’s Rule?

When digits are reduced in amniotes, the first ones to be lost are the outermost and innermost fingers—that is digits V and I of the pentadactyl hand.

What are some of the possible functions for the development of feathers?

thermoregulation, sexual selection, water repellence, foraging, nesting and defense

Explain the Cursorial Theory (“Ground-Up”)

Ancestors lived on the ground, used long legs to run fast with limbs outstretched, were eventually lifted-up by wind currents and carried into flapping flight

Explain the Arboreal Theory (“Trees-down”)

Bird ancestors lived in trees, jumping from branch to branch, and eventually glided into flapping flight.

What is an example that supports the “GROUND UP” theory

The existence of proto-feathers on Caudipteryx and Sinosauropteryx demonstrates that life in the trees was not a prerequisite for the evolution of feathers

What is an example that supports the “TREES DOWN” theory

the clawed feet of Archaeopteryx

Birdlike relatives appeared how many years ago?

165 million years ago

What is significant about the Enantiornithine wing found in amber?

The fossil demonstrates that plumage similar to modern birds was already present 99 million years ago

Why is convergent evolution a problem in bird classification? Provide examples.

Two completely unrelated groups of animals may evolve a close physical resemblance because of behavioral and ecological similarities.

Ex.) Alcids and Penguins OR Swifts and Swallows

Why is divergent selection a problem in bird classification? Provide examples.

Closely related species (or groups) evolve such distinct physical and behavioral differences via natural selection that their true evolutionary affinities are not at all obvious.

Ex.) Grebes + Flamingos

Describe contour feathers

they form the acrodynamic shape of the bird and may have extensive fluffy segments lacking interlocking barbules for insulation

Fill in the blank:

The feathers on most birds are grouped into______________. Between tracts are regions of ________________.

1. Feather tracts (pterylae)

2. Bare skin (apteryla)

Provide an example of a species in which feathers are distributed evenly for insulation

Penguins

Describe flight feathers

A special kind of contour feather. They have long rachis and prominent vane; are attached to the major limb bones.

Provide an example of a species able to practice “silent” flight

Owls; they have velvety wings

Most birds have 12 rectrices (tail feathers)… name an exception to this.

Grouses have 18

Snipes have 24

Describe down feathers

Totally lack hooks and (usually) a rachis, lie close to the skin.

A variant: powder down feathers for waterproofing

Describe semiplumes

Unlike contour feathers, barbules lack hooks. Unlike down feathers, the rachis is longer than the longest barb. Provide insulation and streamlining.

Describe filoplumes

Have long shafts but relatively little vane, are used for mechanical sensory purposes such as monitoring positions of feathers without receptors.

Variant: Bristles (help protect eyes)

Give an example of a species with bristles

Nightjars

List the forms of feather care

1. Preening

2. Oiling

3. Head scratching

4. Bathing

5. Anting

Describe feather pigmentation

colored substances that can be extracted from feathers

Describe feather structural colors

depend on the actual physical structure of the feather to reflect certain wavelengths of light (similar to prism)

What colors are produced by melanins? Provide a species example

Brown, grey, black, tan

Ex.) House sparrow

What colors are produced by carotenoids? Provide a species example

reds, pinks, oranges, and yellow

Ex.) House finch

What colors are produced by porchyrins? Provide a species example

some reds, some browns, and greens

Ex.) Turacos

What colors are produced by psittacofulvins? Provide a species example

red-to-yellow hues in parrot feathers

Ex.) Macaws

What colors are produced by structural colors? Provide a species example

bright green, blue, and iridescences

Ex.) Anna’s Hummingbird OR Blue Jays

Describe the difference between superblack and normal black plumage. Provide a species example

Normal - The barbules are simple, undifferentiated and generally oriented horizontally

Super Black - The barbules are strap-shaped and utilize a variety of 3D surface structures to produce multiple scattering, which enhances light absorption by melanin.

Ex.) Greater Lophorina

What are the stages for feather replacement?

first basic, second basic, definitive basic plumage.

basic= non-breeding

alternative= breeding

When does prebasic molt become available?

Usually late summer or early fall; usually not a complete molt.

When does prealternate molt become available?

The second molt, usually a partial one, happens in the spring prior to breeding.

List some of the differences between Birds and Mammals in regards to their internal systems of metabolism and excretion.

• Higher Basal Metabolic Rate

• Higher Body Temperature

• Faster Heart Rate

• More efficient Respiratory System

• Higher Blood Pressure

• Higher Blood Sugar Concentration

What can birds do to dissipate heat?

• Expose bend of wing

• Panting

• Ruffling of crown feathers

• Ruffling of back feathers

• Wet abdomen

• Expose the legs

Provide an example of passive measures for a bird to dissipate heat

Ruffle feathers, excrete on exposed legs, spreading wings in the wind, seek shade, or bathing

Provide an example of active measures for a bird to dissipate heat

Panting OR Gular fluttering (evaporate water loss from the mouth and upper throat)

What can birds to to retain heat?

• Fluff out feathers

• Sunning

• Posture

• Huddling

• Counter current system in exposed body surfaces: leg wattles, etc

• Shivering (active measure)

Explain Bergmann’s Rule.

Bergmann's rule states that animals in colder climates are larger than animals in warmer climates. This rule is based on the idea that larger bodies retain heat more efficiently. 

How many air sacs do birds have? List an exception to this.

Typically 9, turkeys are an example of a species that does not conform to this, they have 7

List the air sacs found in the respiratory system

• paired cervical

• paired anterior thoracic sacs

• paired posterior thoracic sacs

• paired abdominal sacs

• single interclavicular sac (important for sound production)

What is different about a bird’s heart?

They have a 4 chambered heart with a given body mass of 41% larger than a mammalian heart

What is the average heartbeat for birds? List an exception for this.

Average heartbeat is 220/min

Small hummingbirds can reach 1200/min

Explain a bird’s water retention mechanism

counter-current cooling in nasal passages cause exhaled air, which is moist from the lungs to be cooled during exhalation, thereby condensing and conserving water

What are some food sources available for birds?

• Seeds

• Insects

• Fruits

• Nectar

• Meat

• Fish

• Etc

Why do some birds eat clay? Provide an example of a species that does this.

It is thought to bind to toxins to neutralize them; especially important in birds that eat many seeds and bitter green fruits

Ex.) Parrots, crossbills

What is the purpose of a cecum near the terminal end of a bird’s digestive tract?

To further ferment partly digested food, produce antibodies, and it aids in the absorption of water.

Explain the relationship between microbes and birds

Microbes provide nutrients, immune defense, and development functions with a myriad of implications for host health and fitness.

Hosts provide microbes with nutrients, a stable habitat, and transmission to new hosts.

What species carries out foregut fermentation in an enlarged crop?

The hoatzin of South America. It feeds on leaves, making its digestive strategy more like that of a ruminant than a bird.

How is bird vision different from human vision?

Birds have more cones, oil droplets in their retinas for UV protection, and ganglion cells that enhance night vision.

How do birds use UV vision?

• Kestrels detect vole urine markings via UV reflection.

• Blue Tits find camouflaged caterpillars using UV.

• Bluethroats select mates based on UV plumage brightness.

What is unique about bird hearing compared to humans?

What is unique about bird hearing compared to humans?

• Birds hear a wider frequency range (e.g., chaffinch up to 29,000 Hz, pigeons as low as 0.05 Hz).

• Birds detect temporal sound patterns better than humans.

Which birds use echolocation and why?

Oilbirds use echolocation to navigate in dark caves

What is the Herbst Corpuscle?

A highly sensitive touch receptor found in wings, woodpecker tongues, and kiwi bills, helping birds detect pressure changes.

How do birds maintain balance in flight?

Using three semi-circular canals in their ears (1 horizontal, 2 vertical) to detect movement.

Bird taste

Birds have fewer taste buds (e.g., chickens ~27, parrots ~300-400), with most located on the roof of the mouth or deep in the oral cavity.

Hummingbirds taste sweetness?

They evolved a T1R1 to T1R3 receptor, allowing them to detect sugar, unlike most vertebrates.

Bird Intelligence

Bird brains are 6-11 times larger than similarly sized reptiles, supporting advanced learning and problem-solving

Three Main Bird Brain Regions and Functions

Forebrain → Intelligence and complex behavior

Midbrain → Vision, muscle coordination

Hindbrain (Medulla) → Spinal cord control, reflexes

Types of Bird Communication

Visual (light) - wave energy in form of light

Acoustic Communication (vibration) - song and sound

What appearance conveys?

Species

Sex

Identity

Reproductive State

Health

Age

Quality

Physiological State

Visual Information

Color - Male house sparrows with large black bibs dominant over those with small bibs.
Ornamentation - Peacocks with more eyespots on tails preferred by women. more costly to produce eyespots
Size - Large cowbird males more dominant than others

Shape - Female Barn Swallows preger to mate with males with more symmetricsal ornaments

Types of Visual Communication

1. Plumage - Age or Condition

2. Badge/Size - DOminance

3. Display - Mating or defense

How Visual Communication Evolves (Mechanism)

Plumage color, molt, feather wear (color changes as they wear) spurs, cosmetics

Signal evolution factors

Signal Efficiency - how well signal propogates/moves

Signal Content - how much info can be in each signal

What evolutionary pressures shape bird coloration?

• Anti-predator adaptations: Crypsis (camouflage) and warning displays.

• Threat/warning signals: Aposematic coloration (e.g., Sunbittern, Pitohui).

Sexual selection:

• Intra-sexual selection: Male-male competition.

• Inter-sexual selection: Signals indicating mate qualit

What makes a signal “honest” in birds?

Honest signals are costly to produce, ensuring they accurately represent an individual's quality.

key theories explaining honest signals?

• Zahavi’s Handicap Principle: Costly signals indicate good genes.

• Hamilton-Zuk Hypothesis: Some costly traits (e.g., long tails) indicate parasite resistance.

• Runaway Selection Hypothesis: Preferences for exaggerated traits evolve over time.

Can bird signals be deceptive?

Yes, some birds use deceitful signals to mislead rivals or mates.

Mutual Stereotyped Displays

Functions (longer term reationships)

• Reaffirm pair bonds (especially in life-long mates).

• Stimulate courtship.

• Coordinate breeding behavior.