exam 1 Flashcards
Diagnostic characteristic
trait shared by all birds, but no other LIVING organisms
Unifying characteristics
- reflect a common evolutionary history
- shared by all birds
- other organsims may also share these traits
Evolution
species have changed over time and are related by descent from a common ancestor
Name a diagnostic characteristic of birds
feathers
Name at least 5 unifying characteristics of birds
1, Bills
2. Skeletal specializations - pneumatic bones, fusion/reduction of bones
3. Bipedalism - digitagrade feet (walk on toes)
4. centralized body mass for flight and balanced walk on land
5. High metabolism
6. specialized circulatory and respiratory systems
7. highly developed CNS and vision
8. large, nutrient rich eggs
9. loss of urinary bladder
10. Loss of teeth (replaced by gizzard)
Natural selection
individuals that survive to reproduce will have higher fitness
Adaptive radiation
process in which organisms diversify rapidly from an ancestral species into a multitude of new forms that fill new ecological niches
ex) galapagos finches diversified their bill shapes to fill new niches
convergent evolution
evolution of shared characers due to similar ecological pressures NOT common ancestry (traits are analagous not homologous)
Phylogeny
the evolutionary history of an organism
Systematics
the field of study that seeks to reconstruct phylogenies
Phyletic evolution
gradual change in a single lineage
speciation
splitting of a single phyletic lineage into two or more
extinction
termination of a lineage
Biological species concept
a group of interbreeding or potentially interbreeding populations that are reproductively isolated from other groups
Phenetics
organisms are grouped based on overall similarity without regard to evolutionary history
Cladistics
some traits are more useful than others in determining relationships, particularly shared, derived traits
Phylogeny
an evolutionary history of a group of taxa described as an evolutionary tree (cladogram) with a common ancestor at the base and descendent taxa at the branch tips
The word ‘taxa’ can describe
a population, subspecies, species or genera
What types of characters should you chose in cladistics?
homologous characters (show the clearest evolutionary relationships)
Homologous trait
a trait that is derived from a common ancestral trait
Analagous trait
does not show an evolutionary relationship between two animals - appears similar due to convergent evolution
ex) bird wing and insect wing
Synapomorphy
shared, derived traits - define a monophyletic group
Symplesiomorphies
shared among all taxa in a phylogeny due to its evolution in a common ancestor
ex) in birds, this might be feathers
Homoplasies
are analagous traits OR reversals
What type of traits are the most useful for classifying high level taxonomic categories?
conserved characteristics
Name some conserved characteristics that can help determine taxonomy in birds
- bony palate - separates paleognathae from neognathae
- nares
- structure of leg and foot muscles
- morphology of vocal apparatus
- behavior
- vocalizations
- downy chick plumage
- toe arrangement
Parsimony
the principle that the most likely explanation is the simplest one - the cladogram that is most likely to be closest to reality is the one with the fewest transitions (losses/gains of traits)
this is based on the assumption that synapomorphies are more common than homoplasies
Monophyletic group
includes the most recent common ancestor of a group of organisms and ALL OF ITS DESCENDANTS
polyphyletic group
does not include the common ancestor of all members of the taxon
paraphyletic group
includes the most recent common ancestor, but not every descendant
Reptiles and birds describe this type of phylogenetic group
monophyletic group
reptiles describe this type of phylogenetic group
paraphyletic group
warm blooded animals (mammals/birds) describes this type of phylogenetic group?
polyphyletic group
Name some steps in the evolution of modern birds
- reversed hallux - grasping or perching foot
- tarsometatarsus - fused leg bones
- carpometacarpus - fused wrist and hand bones
- pygostyle - shortened tail vertebrae/fusion of bones
- keeled sternum - attachment of flight muscles
- modern coracoid - modified shoulder joint allows movement of wing above head
- alula - facilitates flight by reducing turbulence, esp. during slow flight
This group of birds that occured ‘after archaeopteryx’ is now extinct
Enantiornithine birds
What are some characteristics of Enantiornithines? (6)
- most abundant and diverse group of avialans in the cretaceous period
- additional modifications for flight
- modern perching foot
- advanced forelimb modifications (raise wings over body and fold them)
- retained teeth and clawed fingers on each wing
- NOT ancestors of modern birds
Name some characteristics of ornithurae birds (2)
- uncinate processes connect ribs and protect thoracic cavity
- loss of teeth
Name 2 branches of extinct ornithurae birds
- Hesperornithiformes - toothed diving birds with larged lobed feet
- Ichthyornithiformes - flying toothed seabirds - like terns
Name the ancestors of modern orders that survived the mass extinction (2)
- Paleognathae - ratites/tinamous
- Neognathae
- Galloanserae (Galliformes - turkey and quail + Anseriformes - ducks)
- Neoaves (procellariiformes - petrels and albatross + shorebirds - sandpipers and plovers)
Feathers
unique epidermal structure composed of a special class of beta-keratins
Types of feathers (7)
- contour feathers
- flight feathers
- down
- semiplumes
- filoplumes
- bristles
- powderdowns
Name the two types of vaned feathers
- contour feathers
- flight feathers
Calamus
the bare part of the feather where it attaches to the bird
Vane
the part of the feather that is connected to the rachis
Pennaceous structure
interlocking barbs
Barb
the part of the feather that branches from the rachis, including the ramus, barbule and barbicel
What is the relationship between the barbule and barbicel
barbicels are hooklike structures that protrude from the barbules
What are some characteristics of contour feathers
- feathers that cover the body and wings
- may have an aftershaft
- symmetrical vanes
What are the 2 types of wing feathers
- primaries attach to the bones of the hand and second digit (fused)
- primaries are numbered starting at ten (X) on the leading edge all the way down to 1 - BIRDS ONLY HAVE 10 PRIMARIES - secondaries - number of secondaries may vary from like 8 to 35 and are numbered in the opposite direction from the primaries (increasing in number towards the body)
Coverts
- cover calami of remiges
- help body be more aerodynamic
- overlap like shingles on a roof
- flight feathers mostly hidden on closed wing
Why are flight feathers asymmetrical?
the leading edge of the feather has a narrow vane to increase stiffness and rigidity and provide lift
flight feathers with coverts combine to make the entire shape of the wing an assymetrical, curved structure to facilitate lift
How are the remiges numbered?
Primaries are numbered 1-10 with 10 being the most distal and 1 being the most proximal
Secondaries are numbered 1-n with 1 being the most distal and n being the most proximal
What are the remiges
Wing feathers
What are the retrices?
Tail feathers
How are the retrices attached?
Attached via ligaments to the pygostyle
Are the retrices pennaceous or plumulaceous?
Pennaceous
Name the 2 types of pennaceous feathers
- Flight feathers (retrices/remiges)
- Contour feathers
What is the function of the retrices?
Steering and landing
Can disrupt airflow to decelerate, or spread/narrow/tilt tail to steer
What are the characteristics of a down feather?
No central rachis
Barbules lack barbicels
Plumulaceous
Thermoregulatory function
Reduced or absent rachis
Natal down
Occurs in young birds, grows in feather tracts and is eventually replaced with contour feathers
Adult down
Occurs all over the body, not just in tracts
What are some characteristics of a semiplume?
-No barbicels
-Plumulaceous
-Traps air (thermoregulatory fct)
-The rachis is longer than the longest barb - KEY CHARACTERISTIC
What are some characteristics of a filoplume?
-Sensory feather with tuft at the tip of the feather
-hairlike
-touch receptors in the skin next to the feather
-fct theorized to be detecting wind speed and direction
What are some characteristics of a bristle?
-sensory feather with tuft at the base
-occur around eyes and bills
-connected to sensory corpuscule at the base
-tactile and protective function (like eyelashes)
Ramus
-the main part of the barb
-barbules attach to the ramus, which extends perpendicular to the rachis
What is the function of rictal bristles?
To funnel food towards the mouth and to compensate for reduced vision when feeding at night
What is unique about the feathers of a sandgrouse?
Males soak up water for chicks to drink out of his belly feathers - like a sponge
What is unique about the feathers of club winged manakins?
They rub their wings together to create sounds and court females
How to hummingbirds court females?
They do courtship dives that force air through their retrices, making a sound
What are the two ways that feathers can have color?
Pigment and structure
Pigment
A naturally occurring substance incorporated into the feather that absorbs some wavelengths and reflects others
Structure (referring to color)
Typically a melanin layer, overlaid by air bubbles that change the wavelengths of light absorbed and reflected by a feather
Melanin
Synthesized from AA tyrosine in melanocytes
Can be deposited to form patterns
What are the two types of melanin?
Eumelanin - brown/grey/black
Phaeomelanin - tans, red-brown, yellow
Why is melanin beneficial to birds (besides colors)
Melanin increases structural integrity and resists bacterial colonization
Carotenoids
-Produced by plants and consumed in the diet as beta carotene and lutein and deposited in keratinocytes
-red, orange, and yellow pigments
Carotenoids
-Produced by plants and consumed in the diet as beta carotene and lutein and deposited in keratinocytes
-red, orange, and yellow pigments
Psittacofulvin
Parrot specific pigment, derived from carotenoid
Porphyrin
Chemically related to hemoglobin and liver bile pigments
Turacin and turacoveridin
Red and green pigments respectively, present in turacos
What are the two types of structural color?
Non iridescent and iridescent
Non iridescent structural color
- same color from every angle
-air pockets in feathers scatter specific wavelengths - larger nanostructure scatters longer wavelengths, making redder colors
- smaller nanostructure scatters shorter wavelengths, making bluer colors
Iridescence
-Color changes depending on angle
- arrays of melanomas in beta keratin of the barbules
- made up of many layers of keratin and melanin rodules
Can birds use a combination of structural and pigmented colors?
Yes - paradise tanager uses structural color and carotenoids in their crowns
Could you say with certainly that a feather is white due to its pigment?
No - you cannot tell visually for most colors what the source of the color is
What weighs more, the feathers or skeleton of a bird?
Feathers
Pterylae
The feather tracts - feathers grow from follicles here
Apteria
Fatherless areas between tracts
Can a feather heal from trauma?
No - feathers are not alive and must be replaced
Uropygial gland
Gland at base of tail that produces preen oil - a substance that is spread over feathers to protect them from wear and parasites
Anting
Inviting ants to come up in your feathers and eat the parasites
Molt
Regular, scheduled replacement of feathers
Describe molt
- Natal down
Pre juvenal molt - grow first set of contours - Juvenal plumage
1st pre basic molt - 1st basic plumage (sometimes only contour feathers get replaced and the bird can be aged here)
2nd prebasic molt - Definitive basic plumage
Prebasic molt
Describe molt for a bird that molts twice in a year
- Natal down
Prejuvenal molt - Juvenal plumage
1st prebasic molt - 1st basic plumage
1st pre alternate molt - 1st alternate plumage
2nd prebasic molt - Definitive basic plumage
Molt limit
Occurs when a bird can be aged based on its feathers
Ex) 1st spring indigo buntings
How can plumage change without molt?
Starling plumage wears down to change color - white spots wear off
Sparrow badge of status shows when feathers wear down
Factors that influence frequency of molt
- Habitat - exposure to sand, sun or wind wears down feathers
- Parasite load - wears down feathers faster
- Migration - causes wear on feathers
- Life history - number of years until sexual maturity
Chord
Straight line width of an airfoil leading to the trailing edge
Camber
Convex shape of an airfoil in cross section - greater closer to body than at wingtip
Proximal camber > wingtip
Angle of attack
Angle at which the leading edge meets the flow of air
Bernoulli effect
Pressure decreases as speed increases - helps birds achieve flight as air moves over the wing faster than under
Newtons 3rd law
Camber shape directs air down, causing an equal and opposite force generating lift
How does the angle of attack help generate lift?
Greater angle of attack = more air directed downward = greater lift
Too much angle, and you stall though
Thrust
Forward component of lift
Downstroke generates…
Thrust
What is the most efficient speed of flight
Intermediate speed
(Faster and slower flight are both more energetically expensive)
How do birds generate lift?
Wing shape and position
What is thrust and how do birds generate it?
Forward component of lift and by changing wing position
What are the two types of soaring?
Thermal and dynamic
Thermal soaring
Ride rising air with very little energy
Dynamic soaring
Exploits differences in wind speed caused by waves/ridges
Turn into wind to gain altitude
Gain speed by gliding down
Ex) albatross
Flapping
Allows each primary to act as an airfoil
On the upstroke, primaries separate to reduce resistance
Alula
Feathered digit #1, allows birds to control movement of air over the top of the wing to maintain lift and prevent stalling at slow speeds or high angle of attack
- prevents turbulent flow and promotes laminar flow (keeping air stuck to the wing)
Most useful at slow speeds or during landing
What are the two types of intermittent flight?
- flap glide - reduces power cost at slower speeds
- flap bounding - reduces power cost at faster speeds
What type of intermittent flight reduces power cost at low speeds?
flap gliding
What type of intermittent flight reduces power cost at high speed?
flap bounding
What is unique about hummingbird flight?
they produce lift and thrust on the upstroke and on the downstroke
What do hovering birds do to prevent stall?
extend the alula and spread the tail
Wing loading
body mass/wing surface area
increased body size = increased wing loading
increased wing loading = increased energy expense
decreased wing loading = fly slower and with less flapping
Aspect ratio
wingspan/wing surface area
high aspect ratio = high lift, lower drag, and lower maneuverability
low aspect ratio = less lift, less drag, and more maneuverability
What are the four broad categories of wing shape?
- slotted high lift - eagle, RTHA
- high aspect ratio - albatrosses and gulls
- elliptical wings - crow, grouse, sparrow
- high speed wings - falcon, duck, swift
Describe a slotted high lift wing in terms of aspect ratio and wing loading
- medium aspect ratio
- low wing loading
- notched feathers to reduce drag and generate lift
- generous use of alula
describe a high aspect ratio wing in terms of aspect ratio and wing loading
- high aspect ratio
- high speed gliding in high wind speeds
- narrow and unslotted wings
- moderate wing loading
- difficult takeoff and not very maneuverable
- increased lift and increased speed
- birds spend most of their lives soaring
What are the two categories of elliptical wings and what do they do?
- low aspect ratio/low wing loading
- drag offset by slotting, high maneuverability in dense habitat
- crow, sparrow, songbirds
- low aspect ratio/high wing loading
- good at bursting flight/not great at sustained flight
- grouse, quail
What are some characteristics of high speed wings?
- medium aspect ratio
- high wing loading
- pointed wing tips and swept back wings
- need to flap to generate lift, have good maneuverability in open habitat
- falcons, swifts, ducks
What are the names of the two muscles that facilitate flight and are attached to the keel?
the pectoralis and the supracoracoideus
Which flight muscle is responsible for the downstroke?
the pectoralis
Which flight muscle is the largest in most species?
the pectoralis
Which flight muscle is responsible for the upstroke?
the supracoracoideus
Which birds have a large supracoracoideus?
hummingbirds and penguins
arboreal theory
flight began with gliding from tree - tree
ie) originated with the arboreal lifestyle
cursorial theory
elongated limbs and leaping made it easier to catch prey
ie) flight benefits predation
wing assisted incline running
flying evolved gradually to assist with climbing up inclines
What are the three different theories for how flight developed?
arboreal theory, cursorial theory, and wing assisted incline running
endotherm
body heat is produced endogenously
ex) mammals, birds
ectotherm
relies on the environment to generate body heat
polikotherm
body heat fluctuates with the environment
homeotherm
maintain their body temperature within a narrow range
all _______ are homeotherms, while some _______ are polikotherms and some are homeotherms
endotherms, ectotherms
what are some costs and benefits of endothermy?
costs - energy expensive, prone to overheating, higher protein requirements
benefits - active at many temperatures, increases speed of nerve impulses, increases muscle fiber contraction strength, increases endurance
basal metabolic rate (BMR)
the minimal energy requirement of resting, non-stressed birds at neutral temperatures
does BMR scale with size?
no, the larger the bird, the lower the BMR
ie) the ratio of BMR:size is larger for small birds and smaller for large birds
What types of activites increase the metabolic rate
extreme temperatures, reproduction, molting and flight all have metabolic costs
thermoneutral zone
the temperature range within which extra energy is not expended to thermoregulate
lower critical temperature
the coldest it can be before a bird needs to start doing something to thermoregulate
upper critical temperature
the hottest it can be before a bird needs to start thermoregulating
what happens at temperatures above the upper critical temperature (UCT)?
evaporative cooling
What happens at temperatures below the lower critical temperature?
shivering occurs
what are some things birds can do to thermoregulate in cold temperatures (6)
- fluff contour feathers to trap air
- tuck extremeties close to body
- change the microclimate (burrow into snow, get close to buildings)
- huddling
- communal roosting
- increase the metabolism
what is the process by which birds become accustomed to more extreme environments (like the cold)
acclimation
torpor
dropping of body temp to closely match the environmental temp, usually down to like 8c
what are some costs and benefits of torpor?
costs
- cannot respond to threats
- time and energy investment in waking up from torpor
benefits
- conserve energy
What is countercurrent heat exchange?
blood vessels carrying warm blood are closely associated with blood vessels carrying cold blood
blood returning to the body is warmed and blood going to the feet is cooled
in this way, the feet are kept just above freezing and heat is conserved
this system can be bypassed in hot environments to lose heat in the legs
How do birds use facultative hyperthermia?
Birds use facultative hyperthermia to reduce heat gain from the environment, reduce water loss and conserve energy
raising the body temperature more than one or two degrees celcius is not good because it denatures protiens and can be fatal
What are some behavioral ways that birds can reduce their body temperatures
- reduce activity during hottest times
- find a better microclimate (think grackles under cars)
- soar at high altitudes to find cool air
- panting and gular fluttering
- ruffle feathers to expose apteria (bare skin between pterylae - feather tracts)
- expose legs
What are some ways that birds dissipate heat? (not behavioral)
- beak dissipates heat
- evaporative cooling
Allen’s rule
appendages of endotherms are smaller relative to body size in colder climates
What size of bird is more vulnerable to heat stress
larger birds
Bergman’s rule
animals are larger in cold climates and small in warm climates
House finches spread across the united states in a short period of time. What rule can we use to predict the body size these house finches?
bergmann’s rule
What are the differences between mammal respiration and bird respiration
mammals
- diaphragm
- chest cavity at lower pressure than the environment
- tidal breathing
- 50% volume inhaled does not participate in gas exchange
birds
- no diaphragm
- air sacs store and pump air
- air flows in a single direction
- air intake on inspiration and expiration
how many air sacs are there?
4 pairs of air sacs, one unpaired and smaller air sacs in the bones
what is the function of the air sacs?
enhance airflow
dissipate body heat during flight
cushion internal organs during flight
may be used in mating displays (frigatebird)
gas exchange DOES NOT OCCUR
if birds do not have a diaphragm, how do they breathe?
via the movement of the ribs and sternum to change the size of the thoracic cavity
what is the path of air through a bird’s respiratiory system?
- nares
- trachea
- posterior air sacs
- lungs (primary bronci/mesobronchi -> secondary bronchi -> tertiary bronchi (parabronchi))
parabronchi are the site of gas exchange
Describe what happens as air moves through a bird’s respiratory system?
- inhalation - air moves to posterior air sacs
- exhalation - o2 rich air moves to lungs for gas exchange
- inhalation - co2 rich air from lungs moves to anterior air sacs
- exhalation - air is expelled from anterior air sacs
What are the functions of a bird’s circulatory system?
- distribute food from the digestive tract to the body
- distribute O2 from the lungs to the body
- remove CO2 from tissues and get rid of it
- remove wastes
- dissipation and conservation of heat
If you control for body size, what is the relationship between mammal and bird heart rate/heart size/stroke volume
heart rate - mammalian heart rates are typically faster than a bird’s
heart size - hearts of birds are 41% larger than mammals when controlling for body size
stroke volume - mammalian stroke volume is smaller, bird stroke volume is larger
What is the difference between white and dark meat?
‘dark’ meat has more myoglobin due to sustained muscle activity (cells use sustained aerobic cell respiration)
Could we expect the breast meat from a migratory bird to be the same as the breast meat from a domestic terrestrial bird?
No, the breast meat of a terrestrial bird is likely to be ‘white meat’ and have less myoglobin
the breast meat of a migratory bird is designed for endurance/sustained activity, thus is will have more myoglobin and be ‘dark meat’
What does a salt gland do?
in seafaring birds, the salt glands allow birds to get rid of excess salt from the nares instead of relying on the kidneys
these birds must drink salt water to survive
