Ornithology Exam II (part 2)

Is torpor facultative or obligate? explain

obligate because it depends on the internal energy reserve

disadvantage of torpor

increases predation risk

advantages of torpor

decreases respiration and conserves energy

function of the gizzard

digests enzyme-laden food, usually surrounded by strong muscles to physically grind

what is cognition?

learning, memory and decision-making based on info that is sensed, processed and retained

function of the syrinx

produces sound, thoracic and abdominal muscle contraction force air from the air sacs. Air molecules vibrate as they pass through external labia and tympanic membrane. 2 passageways = 2 types of sound produced at once

zugunruhe

when caged migratory birds become restless before their expected departure to migrate; occurs until about midnight

fallout

when birds settle along the coasts to avoid storms during migration

advantage of high metabolism

activity not constrained by low ambient temperatures

T or F: the avian lung occupies less space than that of a similar size mammal

true, it occupies 50% less space

T or F: the avian heart weighs at least twice as much of that of a similar size animal

true, constitutes 2-4% of their mass relative to <1% in small mammals

Rapoport’s rule

species tend to have larger geographical ranges at higher latitudes; geographical ranges tend to decrease as you get closer to the equator/migrate less

probing, spearing woodpecker tongue

has bards at the tip of the tongue, hyoid apparatus used to greatly extend its tongue

tradeoffs of binocular vision. example species?

enhanced depth perception, wider field of view , but is bulkier and heavier than monocular vision. ex) owl

tradeoffs of monocular vision. example species?

uses one eye at a time making it more compact, portable, partially less expensive, but leads to eye strain, reduced depth perception, narrower field of view. ex) pigeon

how do avian eyes differ in vascularization relative to mammalian eyes?

they have a pectan, highly vascularized to provide more O2 to avascular retina, mammals have capillaries throughout the eye

human hearing compared to passerine/owl hearing

most birds hear well only over narrow range of frequencies relative to humans; owls have auditory sensitivities well below humans across range of kHz

what are the intelligent bird groups

corvids/passerines, falcons, hawks, W-peckers, herons,

what’s the bird/mammal brain size % relative to reptiles?

bird/mammal brains account for 2-9% of their total body mass, this is 10x that of reptiles

parts of the avian brain

cerebral hemisphere, optic lobe/cerebellum, hyperpallium, hippocampus

insight learning

learning by observation or imitation, considered advanced. Blue Jays learn the difference b/w edible and non-edible butterflies by watching the feeding behavior of other jays

2 functions of calls

1. threat display/individual recognition 2. used to coordinate a pair, family or flock during migration

2 functions of songs

1. territorial defense 2. mate attraction

male and female differences in songs and calls

calls made by either sex; in most species, males sing and females do not; clusters of neurons that control ability to sing are smaller in females than in males

T or F: tropical birds do not have a breeding season

false, tropical birds do have this

meta tool use. example?

using one tool to modify or enhance another. Caledonian crows given a stone, 5cm stick and 18cm stick beyond their reach, they used the 5cm stick to get the 18cm stick

how is radar used as a conservation tool?

reduces risk of collision with manmade structures, tracking trends in bird abundance, ID and conserve stopover sites

vocalizations as honest indicators

evidence that vocalizations are honest indicators of size, beneficial to prevent male/male fighting

how does frequency differ depending on the species?

grassland birds have higher frequencies, forest birds have lower frequencies

T or F: air sacs are unique to the class Aves

false, basal theropods had posterior air sacs

how do birds dissipate heat?

feather ruffling, wing bending, panting and leg exposure

function of the crop

stores and ferments food for digestion

function/benefit of seeing in UV light?

UV transmitters in feathers used for species recognition, health assessment, sexual cues; functions as an indicator of offspring health

difference in olfactory sense in birds vs. humans

size of olfactory bulbs smaller in birds relative to humans, number of olfactory tubules dependent on the species

stopover site

areas that are temporarily used by birds during migration for resting, predator avoidance, and refueling

3 hypothesis for regional dialects

historical hypothesis, race specialization/ecological hypothesis, social adaptation hypothesis

Sabrose and Renne research

are cultural components of avian alarm calls lost when predators are absent? use black-capped chickadees as a model- alarm calls convey information about survivorship, breakdown of calls suggest increased connectivity between otherwise culturally isolated populations

salt gland

most developed in oceanic birds, folded nasal tubes extract salt from the blood via capillaries, salt is excreted near the nostrils; ducks can enlarge theirs when drinking saltwater, passerines don’t have them

metabolism

energy expenditure (KJ/Kcal) or O2 consumed per unit body mass per unit time

function of the proventriculus

secretes acid and gastric juices; pH as low as 0.2-1.2 can dissolve bones; some species regurgitate oil from here to feed chicks

how do birds generate heat?

shivering, non migratory birds may increase feather mass up to 65%, fluff feathers, metabolism increases in the winter

Bergmann’s rule

as we increase in latitude body size tends to increase within a species; increased surface area = lower heat loss; due to SA:V ratio, northerly individuals of the same spp. tend to be larger

avian eye characteristics

cornea, 2 groups of stratified muscles attached to sclerotic eye ring, pectan, tampum lucidum, nictating membrane, cone density

avian respiratory system

unidirectional air flow; 1. air inhaled, goes from trachea to posterior air sacs 2. first exhale forces air into lungs 3. air inhaled, low O2/high CO2 air into anterior air sacs 4. air is released

T or F: in early spring trans-gulf migrants accumulate fat but wait for favorable winds

true, the wait for favorable tailwinds before migrating

3 compasses birds use during migration

1. position of the sun during the day/ stars at night 2. landmarks 3. earth’s magnetic field

3 factors that have changed since 18,000 years ago

1. more rapid climate change 2. heavily fragmented landscape- smaller/lower quality stopover sites 3. destructions of breeding and wintering habitats

2 reasons a bird might exhibit geophagy

consumption of grit to physically break down food, (-) charged clay and minerals bind to (+) charged ions of immature fruit

disadvantage of high metabolism

water and energy demands are often spatially/temporally scarce

torpor

energy-saving state characterized by lower internal body temp and low activity; hummingbirds, swifts, pigeons

pectan

unique avian feature, highly vascularized to provide O2 to an avascular retina

ossicle bones

12-15, modify the lens and cornea for focusing

tapetum lucidum

nocturnal birds, reflect light back through the retina for increased light capture

what are the cornea and lens attached to?

sclerotic eye ring

sclerotic eye ring

composed of 12-15 ossicle bones

historical hypothesis

genetic drift, dialects result from species colonizing new regions

race specialization/ecological hypothesis

populations may locally adapt to a region due to environmental conditions

bill diversification

diverse in shorebirds, likely due to character displacement, morphology fits lifestyle

how do birds time their annual migration cycle/judge seasons?

temperature and photoperiod

social adaptation hypothesis

dialects develop when young males disperse into an area and learn the songs of established males

fercula

expands/contracts when flapping to further force air

conchae

air inhaled through the nostrils, folds cleanse/heat the air and remove water from exhaled air

surface area: volume ratio

as we increase in latitude, body size tends to increase; smaller animals lose heat faster

how do avian eyes differ from human eyes?

humans have all photoreceptors located at a 0 degree line of sight for outstanding depth perception, raptors have receptors at 22 and >45 degree line of sight, creates drag visual acuity dilemma for fast moving raptors

cone density in avian eyes

2-5x higher than in humans, make color vision more accurate

cerebral hemisphere (forebrain)

functions for complex behaviors, sensory integration, learned intelligence

optic lobe/cerebellum (midbrain)

regulates vision, muscle coordination and balance, physiological controls

hyperpallium

controls advanced learning and cognitive abilities, occupies a lot of the brain

hippocampus

spatial and cognitive memory

circulatory sustem

4-chamber heart, metabolic rate and oxygen demand strongly positively correlated, more mitochondria in muscles require more energy