#1 Brain & Senses

What order is the Oilbird in?

Caprimulgiformes

What does the Oilbird eat and live?

• frugivore

• caves

What unique sensory ability does the Oilbird have?

It uses echolocation in caves — the only bird known to do this

Why are the Oilbird’s eyes large?

They contain many rods, making them highly sensitive to low light.

How does the frequency range of bird sounds compare to humans?

Birds’ hearing range is similar to ours but may differ in sensitivity

What unit is used to measure sound frequency?

Hertz (Hz)

• meaning cycles per second

What is the typical range of bird vocalizations? What about Humans?

• 2–7 kHz

• 0–20 kHz

What special feature does the Barn Owl’s skull have?

It is asymmetric, enhancing sound localization

What is binaural fusion?

The brain’s processing of timing and loudness differences between ears to determine sound direction

How do owls use binaural fusion to help find the location of a sound?

If a sound wave reaches one ear faster than the other, it most likely means the noise came in that direction

What is the function of the Barn Owl’s facial disk?

It funnels sound to the ears to help pinpoint prey

What does interaural time and level difference refer to?

The time and loudness difference between sound arriving at each ear

• used for directional hearing

What is the Peregrine Falcon’s main prey?

Other birds in open habitats

How does the structure of bird eyes compare to mammals?

Its similar

• birds have proportionally larger eyes

  • up to 50% of cranial volume

What adaptations allow birds to have larger eyes without heavy skulls?

Sclerotic ossicles extend eye volume beyond the skull

How does eye placement affect vision type?

• Side placement =

  • monocular/panoramic

• front placement =

  • binocular

What vertebrate group has a similar eye structure to birds?

Reptiles

Function of pecten in bird eyes

Increases blood flow to the eye

Function of the Pupil

increased light cast on retina; precise image control

• large

What are sclerotic ossicles?

Small bones supporting the eye structure

How many types of cones do birds have?

Four

• including one sensitive to UV light

Retinal fovea

A region with high cone density for sharp vision

Why do birds like terns have pointed eyes?

To focus light precisely and increase surface area for visual acuity (sharp or clear vision)

What is an example of UV-based signaling in birds?

Rhino Auklet horn fluorescence

• Additional rods and cones to pick up on these light waves

Function of flattened eye shapes

Wide-angle lens, small image, enhanced scanning

• Ex: Sparrow

Function of globose eye shapes

Zoom lens, large image, curved cornea gathers light

• Hawk

Function of tubular eye shapes

Zoom & low f-stop, many rods, long optical axis

• Owl

How do birds adjust to underwater vision?

By using ciliary muscles to rapidly change lens shape and compensate for light refraction under water

What sensory adaptations do kiwis have?

Strong sense of smell and tactile bristles around the beak for foraging

• Forage for inverts, seeds, worms

How does the Wilson’s Snipe locate food?

Uses tactile feeding to probe for invertebrates in soft substrates

What are some mechano-reception sensory abilities in birds?

• Skin/feather follicles/feet

• Herbst corpuscles in tip of bill, tongue

What are Herbst corpuscles?

Modified nerve endings that detect pressure/vibrations in bills and tongues

• Ability to adjust their bill easier without being able to see where it puts the bill

Do birds have a good sense of smell?

Generally moderate, but varies by species

Which birds have exceptional olfaction?

• kiwis

• vultures

• shearwaters

What was the old misconception about birds and smell?

Until the 1970s, it was believed birds couldn’t smell

• 80s and 90s – birds can smell, just poorly

• Recently – birds probably use smell about as much as other vertebrates

What is the migration record of the Bar-tailed Godwit?

12,000 km nonstop from Alaska to New Zealand

What adaptations help Bar-tailed Godwits during migration?

Fattening before flight and gut shrinkage during flight

How do Bar-tailed Godwits know when to leave Alaska?

• Intense Zugunruhe 

• Storms

  • Cool sensory system to know what is going on in the local weather-> sense pressure changes

    • Paratympanic Organ

Paratympanic Organ

pressure sensor in the middle ear

• Innate barometer

• Senses changes in atmospheric pressure

Do birds have taste buds?

Yes, but fewer than mammals

Can Tanagers or Manakins taste differing sugar concentrations?

Tanagers (can distinguish 8%, 10%, 12%)

• manakins cannot

Why can tanagers taste better than manakins?

• Behavioral or something innate involved

• Tanagers crush their fruit

  • Can taste the fruit more/more exposure to the sugar 

• Manakins swallow it whole

Why is the avian brain tilted?

To accommodate large eye orbits

• Brain is in “upright” position

Which senses are most developed in birds?

• Sight

• Sound

Which groups of birds are considered most intelligent?

• Corvid and pigeons 

• parrots

Pigeon Intelligence

• Memorize ~725 visual patterns

• Categorize natural vs. human-made objects

• Distinguish art styles (cubist vs. impressionist)

Which bird has intelligence to use logic and visual communication?

Pigeons

Corvid Intelligence

• Make and use tools

• Show episodic memory

• Re-hide caches to prevent theft

Which bird has the intelligence to recognize humans and share that info?

Corvids

Why is the hippocampus large in corvids and parids?

Supports spatial memory for caching food

• Must remember locations

  • Have many different locations

  • Can’t find them-> good for the seeds as they can disperse and survive now

How might bird intelligence affect conservation ethics?

Higher perceived intelligence can increase moral value and conservation funding