ornithology final exam (2)

Do birds rely on their vision or hearing more?

Vision

Which groups of birds have the best vision?

Songbirds and raptors

Can birds see into the ultraviolet spectrum and what decisions are made based on these colors?

Yes, birds can see UV and use it for social and sexual selections.

Describe the differences between binocular and monocular vision.

Monocular – seeing through one eye; Binocular – seeing through both eyes.

Where do birds generally use binocular vs monocular vision?

Binocular – directly in front; Monocular – around the sides.

What is the nictitating membrane?

A thin transparent eyelid used for cleaning the cornea or for diving birds.

What are the three main structures of the avian ear?

External, middle, inner.

What are semi-circular canals and their function?

Three tubes in the ear for balance and equilibrium.

How does the size of the semi-circular canals relate to flight performance?

Larger canals = greater flight ability.

Define mechanoreceptors and give two examples of their use in birds.

Specialized nerve endings that respond to mechanical stimuli; e.g., woodpeckers use them on bill tips, waterfowl have them on bills.

Describe a bird’s sense of taste.

Few taste buds; can only taste basics – sweet, salty, sour, bitter.

Describe a bird’s sense of smell and how it is used.

Similar to mammals; used to find food and identify individuals.

What are the three main components of a bird's brain?

Forebrain, midbrain, hindbrain.

What does the forebrain do?

Responsible for behavioral instincts, sensory integration, and learned intelligence.

What is the function of the midbrain?

Regulates vision, muscle coordination, balance, physiological controls, and seasonal reproduction.

What does the hindbrain do?

Links the spinal cord and nervous system to the brain.

Why are synapses created and destroyed in birds?

Adult brains are dynamic; new synapses created in spring, destroyed in fall (e.g., chickadees increase hippocampus size for seed caching).

Describe the two kinds of sleep exhibited by birds.

Slow Wave Sleep (SWS) – one side of the brain sleeps; REM sleep – both sides sleep.

How can birds sleep during flight?

Using unhemispherical SWS to glide up on thermals and REM on the way down.

What is a benefit of cognition in birds?

They can use tools.

What are the costs of cognition?

Greater investment in metabolic and cellular resources; longer incubation periods.

What is the sound producing organ in birds called?

Syrinx.

What is the difference between a bird song and a bird call?

Song – longer vocal displays; Calls – short, simple vocalizations.

Which calls are more effective for long distance communication and why?

Low frequency calls because they are less subject to distortion.

What songs are best in open habitats and why?

Songs that are not distorted by reverberations off vegetation.

What is a vocal repertoire?

All calls and songs a bird can make, varying due to partially learned social behavior.

Did birds at some point lose the ability to make sounds?

Yes, they evolved the syrinx to regain this ability.

What are the four groups of birds that can learn to sing?

Oscine songbirds, parrots, hummingbirds, neotropical suboscine bellbirds.

How do different bird dialects develop?

Learning errors or innovations in vocalizations from neighbors.

How do new songs become established in a population?

Through young birds colonizing new areas or imperfect learning.

Define vocal mimicry and its purpose.

Mimicking other sounds to enhance the bird's repertoire.

Do female birds sing? Why or why not?

Yes, including duet behaviors for communication and strengthening pair bonds.

How do songs and song repertoires evolve?

Through sexual selection.

What drives vocal performance evolution?

Evidence suggests both genetic quality and female preference.

What cues activate internal endocrine systems?

Environmental and social cues.

What are the three main efforts birds invest in beyond survival?

Reproduction, molt, migration.

What is the annual cycle of birds?

Migrating North (Spring) -> Breeding (Summer) -> Migrating South (Fall) -> Overwintering.

What are the three main tasks of the simplest annual cycle?

Breed, molt, survive.

Do all birds follow a 12-month annual cycle? Give an example.

No; some may breed every six months or few years (e.g., species with shorter cycles).

What do internal clocks regulate?

Reproduction, molt, sleep, feeding, migration.

What is the difference between endogenous and circadian rhythms?

Endogenous rhythms use hormones; circadian rhythms use a 24-hour clock.

What is the function of the pineal gland?

Houses the biological clock.

What do the paired nuclei on the hypothalamus do?

Release neurotransmitters regulating metabolic activity.

What structure and hormones are key in hormonal control of the annual cycle?

Pituitary gland; luteinizing hormone and follicle-stimulating hormone.

What is the role of luteinizing hormone?

Testosterone production in males; progesterone and testosterone in females.

What is the role of follicle-stimulating hormone?

Sperm production in males; egg follicles in females.

Define proximate factors and give 3 examples.

Immediate environmental and physiological triggers; hormonal changes, food availability, weather.

Define ultimate factors and give 3 examples.

Evolutionary drivers maximizing fitness; migration timing, resource competition, reducing predation.

Define zugunruhe.

Migratory restlessness.

Define hyperphagia.

Excessive eating in spring.

Do sex hormones directly regulate migration? If not, what does?

No, migration is indirectly set by springtime activities.

Why are reproduction and molt scheduled differently?

Both are costly and need to occur when self-maintenance costs are low.

What is an issue with climate change for birds' annual cycle?

Mismatched timing leading to food supply issues and shifting evolutionary trajectories.

Why do birds migrate?

To take advantage of seasonal opportunities such as food and nesting sites.

Define flyway.

Major migration routes, particularly North-South in the Americas and East-West in Eurasia.

When do birds migrate and why? Give an example.

When travel is less costly and safe; e.g., blackpoll warbler flying 3 days over 3000 miles of ocean.

What is a migratory fallout?

When birds ground themselves due to exhaustion, especially in bad weather.

Why do birds store fat for migration?

Fat yields 2x the energy per gram; flight distance depends on fat reserves.

Describe stopover sites during migration.

Places for birds to rest, refuel, and seek shelter.

What are the costs and benefits of obligate migrants?

Less winter mortalities; later access to territories and food in spring.

What are the costs and benefits of facultative migrants?

Higher winter mortalities; better access to territories and food in spring.

What is the difference between obligate and faculative migrants?

Obligate migrate yearly; facultative migrate in response to conditions.

What do birds use to navigate during migration?

Landmarks, Sun & stars, Geomagnetism, Odors, Twilight cues.

How do young birds know when to migrate?

Innate internal mechanisms and learning from parents.

Define sexual selection.

Mating success based on competition and female preference.

What drives evolution of ornamentation in birds?

Female preference.

Define sexual dimorphism.

The sexes of the same species show different morphologies.

List and describe the 3 main theories of why females choose mates with elaborate plumages.

Good genes, direct benefits, arbitrary choice.

Define lek.

Gathering of males defending territories to court females.

What are the three models for the evolution of leks?

Hotspot, Hotshot, Female Preference model.

How do song repertoires enhance low-quality males?

Shows females that they are more experienced.

Know the male and female reproductive systems.

Males: testes -> vas deferens; Females: eggs -> oviduct -> uterus.

What are the bird sex chromosomes?

Females: ZW heterogametic; Males: ZZ homogametic.

What are the principal sex hormones and their behaviors?

Follicle stimulating - gamete production; Luteinizing - hormone secretion.

Can birds select the gender of their offspring?

Yes; female body condition influences sex (e.g., Seychelles warblers favor females).

What is an extra-pair copulation (EPC)?

Mating outside established pair bonds.

How have female birds evolved against EPCs?

Corkscrew vagina.

Know the main components of an egg and their functions.

Albumen – water supply; Yolk – food supply for embryo.

Know the 7 breeding systems discussed in lecture.

1. Monogamy 2. Polygamy 3. Polygyny 4. Polyandry 5. Polygynandry 6. Cooperative Breeding 7. Brood Parasitism.

Define monogamy.

One male and one female pair.

Define polygyny.

One male and multiple females.

Define polyandry.

One female and multiple males.

What is cooperative breeding and its benefits?

Helpers care for young; leads to territory defense and skill enhancement.

What is the difference between intra- and interspecific brood parasitism?

Intra – same species; inter – different species.

What is the difference between obligate and facultative brood parasites?

Obligate – lay eggs in others' nests only; facultative – have own nest but also lay in others'.

What are counter adaptations to brood parasitism?

Nest defense, distraction, concealment.

Describe effects of brood parasitism on host populations using an example.

Reduces host fitness; cowbirds can drive species to extinction.