Brains and Senses

eyes

large = wide views and sharp images, not very round

eye movement

limited in orbits, long neck compensate

eye anatomy

(diagram) similar structure, difference shape

cramptons muscle

can change the shape of the cornea, gives greater range of accomodation in terms of light

second fovea

54% of birds (birds of prey, hummingbirds, swallows, kingfishers), enhanced sideways viewing

sclerotic ring

12-15 small bones, helps ciliary muscles focus the lens, holds eyeball in place to prevent movement in the socket, protects during intense changes in air pressure, especially pronounced in owls

nictitating membrane

“third eyelid” translucent, protects the eye, cleans the surface of the cornea, keeps it moist, some aquatic use as window-like area

iris color

some have patterns, most often sold, concentric circles

variation

within species, age, s3x, and in breeding season

visual spectrum

4 cone types: red, green, blue, UV/ violet

monocular vision

most birds, use each eye independently. scan for larger field of view (ahead and behind at same time), lack accurate depth perception

predatory bird field of vision

monocular with binocular overlap. combines panoramic, monocular, and long distance vision with high photoreceptor density, allowing for prey spotting from up to miles. greater depth perception

motion parallax

type of depth perception cue, closer objects appear to move faster, created with head movements

head bobbing

forward backward head movement during locomotion, hold and thrust phases

peering

side to side while perching

pigeon motion parallax

narrow binocular visual field and depend less on binocular depth cues

owls motion parallax

judge distances, pinpoint sounds, and fine-tune their vision and hearing

semi-circular canals

balance and equillibrium

columella

bony or cartilaginous rod in middle ear that transmits sound from the tympanic membrane (eardrum) to the inner ear, the only ossicle

aquatic bird ears

middle ears adapted for their amphibious lifestyles

paratympanic organ (PTO)

sensed barometric pressure changes, detect low pressure (storms — respond by perching more), acts as altimeter. strong indicator of migration initiation

hearing

external ear absent, funnel shaped opening, can detect sounds within a similar range to humans, some use echolocation

ear conch

flap of skin that covers the ear

ear tufts

skin projections covered in feathers, display and communication mainly, some camouflage, nothing to do with hearing

sound localization

two coordinate system — elevation: vertical dimension, azimuth: horizontal dimension.
asymmetrical ear location

worm/bug finding

listen to soil, run, stop and tilt head — focused hearing and enhanced vision in 1 eye, run again. sound to find, vision to strike

magnetoreception

complex migration navigation, one of the main senses (with sight and sound), celestial cues and magnetic field to navigate

megnetite

particles in the skin in the area around the beak

photopigments

in the right eye, enable birds to “see” earths magnetic field lines

taste

likely similar to mammals, 300 taste buds, few to none on the tongue, most deep within oral cavity, detect most flavor categories, helps identify nutritious foods

capsaicin

“flaming” effect on the mammalian oral epithelia and taste buds, birds are unaffected

smell

olfaction comparable to some mammals. used for finding mates, food, and orientation

mechanoreception

primary skin sensitivity

specialized corpuscles

transient touch, velocity, temperature, and vibration. located to help birds transport food. some help birds detect movement of prey from several centimeters away

somatic sensitivity

specialized clustering of touch receptors in the bill, in some birds (ducks, parrots), comparable to human fingertips. tactile foraging means higher density of corpuscles than visual foragers. some birds (brushturkeys) sense nest temperature with their tongue

bird brains

6-11x as large as like-sized reptiles. greater “cognitive power” per gram than mammal brains

spatial memory and hippocampus

nuthatches, titmice, corvids, chickadees. increased spatial memory of seed-caching — enlarged hippocampus

cognition

perception, learning, memory, and decision making. process sensory information for retention and action choice. different cognition correlated with brain size (foraging skills, cooperative breeding, parental care, long life span, and play behavior) master complex problems, outperforming many mammals in advanced learning experiments

krushinsky problem

a behavioral experiment measuring an animal's "elementary reasoning" or cognitive extrapolation ability, often involving navigating to a food source that disappears behind a screen. It tests if animals can understand physical laws to predict the location of food after it moves out of sight

intelligence

crows and their relatives excel at tests of object permanence, delayed gratification, memory and future planning, reasoning, self recognition, theory of mind — mental states of others such as funerals

counting

birds more easily master counting problems than monkeys. raven and parakeets can count up to 17 and can identify a box containing food by counting the number of small objects in front of it.
crows can be trained to produce a number of calls in response to random visual cues and use their voiced to communicate specific quantities, never been documented in other animals.

smart feeding

tend to choose food of high energetic profit (medium size flies targeted bc large flies take too long to subdue and swallow). many birds drop hard shelled prey from the air to crack it open.

insight learning

learning by observing others

insight learning examples

blue jays learn the difference between edible and inedible butterflies by wayching the feeding behaviot of other jays. egyptian vultures throw stones at ostrich eggs (novel tool use). some herons use pieces of bread or other objects as fishing bait. great tits learned to tear the cardboard caps of milk bottles to drink the contents

behavioral innovation

adapt behaviors to find food, solve problems, or survive in a new environment. a key factor in the success of alien birds establishing in new places. not equally distributed across all birds, increases with forebrain size across a variety of bird species

tool use

burrowing owls collect dung from local mammals and scatter it around their burrows to draw in dung beetles. several species use sticks or “hooks”

alex the grey parrot

learned absence or presence of similarity and difference between two objects. intelligence on a level with dolphins and great apes

the columban simulations

two pigeons were taught to “talk” to each other by pressing buttons. a colored light would appear behind a curtain that only pigeon 1 could see. pigeon 1 would peck a button to tell pigeon 2 the color of the light. the second bird would then select the correct color from a set. when performed with 1 pigeon, the bird would use the middle buttons to “take notes”

memory and future planning

capacity to mentally reconstruct personal events from the past (episodic memory) and imagine possible future scenarios

site fidelity

returning repeatedly to the same site. can vary based on personality, breeding stage, and habitat

traplining

visits food sources on a regular, repeatable sequence. hummingbirds form specific routes to minimize competition and maximize nutrient availability

sleep

exhibit slow wave sleep (SWS) and REM to restore brain function

unihemispheric sleep

sleeping with one eye open. opposite side of the brain sleeps, allows them to stay alert for predators

dreams

electroencephalograms during REM suggest that birds dream. patterns of neuronal activity lead to syringeal muscle movements that can be modeled into songs. zebra finches “practice” new song pattens in their dreams