Birds Flashcards
What Clade includes modern birds
Aves
Basal Theropods characteristics
-Bipedal
-elongated a-shaped necks
-hollow post cranial bones
-filamentous protofeathers
Furcula
Bone made from fused clavicles “wishbone”
Lunate wrist bone
Brings increased mobility to the wrist of birds
What type of feathers do birds need to fly
Asymmetrical feathers for flight
Feathers on one side of the cane are linger than feathers on the other side
Why did transitional bird forms have wings covered in feathers but couldn’t fly?
- Using these to glide down from trees
- Short periods of flapping flight
3.flap to help move uphill when running
Exaptation and example
A trait that initially serves one function and is co-opted for a different function
Feathers may have originated for social communication
Feathers co-opted for flight
Adaptation for communication and an exaptation for flight
Theropods capable of powered flight are known as…..
Avialae or avialans
Archaeopteryx characteristics
-skeleton looks like a reptile but has feathers
-capable of powered flight but lacked keeled sternum needed to support strong flight muscles and had restricted shoulder movement
-Had teeth (contrast to modern birds)
-lived during Jurassic, middle of Mesozoic)
Avialae
Clade that included extinct and living groups of theropod dinosaurs that were capable of powered flight
Aves characteristics and time period
-shift in body posture so that center of gravity is above the feet
-reduced tail
-loss of teeth
-a keeled sternum to which flight muscles attach
Appeared shortly before Cretaceous
Birds are derived from….
Theropod dinosaurs
Lift
Angle of attack
An upward force that causes a bird to ride based on the difference in pressure above and below the wings as a bird moves through the air
Air passing below the wings results in higher air pressure (lift) below the wing than above the wing. Lift increases the angle of attack, but only to a point
Proximal wing
Distal wing
-produces the majority of lift
-shoulder socket directed up and out increases range of motion
-ulna supports secondary feathers
-provides majority of the thrust
-elongated and fused digits support primary feathers
-lunate (curved) wrist bone increases range of motion
Skeletal characteristics of birds that enable flight
-pneumaticized bone (hollow)
-most vertebrae except cervical are fused
-keeled sternum: string flight muscles attach
-furcula: fused clavicles separate the shoulders and store energy with each wing beat
-keratinized beak with no heavy teeth
Large muscles that attach to Keel (Keel sternum)
-Supracoracoideus: raise wing
-Pectoralis: depressed the wing (power stroke)
Most feathers are ______ feathers
Contour
Primary, secondary and tail feathers
Feathers that are vaned and important to flight
Cover and protect down feathers
Flight feather characteristics
Primary and secondary
Asymmetrical and vaned (smooth webbed feather surface formed by interlocking barbs)
Streamlined body
Functions of feathers
Flight
Waterproof
Insulation
Visual signs
How do birds respire
Flow through ventilation
One-way flow of air through lungs, also found in crocodiles but not in other living reptiles
Requires two full respiratory cycles (inhale/exhale) to move air through system
Bird lung is called a …..
Does it have alveoli
Parabronchial lung
No, when air enters it passes through tube-like parabronchi
Bird inspiration and expiration steps
- Bird inhaled air #1, which travels down the trachea to the posterior air sac
- Bird echoes air #1, which travels into the parabronchial lung
- Birds inhaled air #2, which travels to the posterior air sac, and at the same time the older air move to the anterior air sac
- Bird exhales air #2, new air travels to lung, at same time, the older air moves to trachea and out of mouth
Each bird breathe travels the following route
Trachea, posterior air sacs, lung with parabronchi, anterior air sacs, trachea
Where does gas exchange take place in birds
What type of system is it
Parabronchial lung
Counter-current
-parabronchi tubes and blood capillaries lay side by side
-oxygen rich air flows in different direction than deoxygenated blood, resulting in rapid diffusion of O2 from air to blood; and diffusion of CO2 from blood to the air
-results in an almost continuous flow of oxygen
What is the most efficient respiratory system of vertebrates
Flow through ventilation of birds
-allows ability to breathe at high altitude
-ability to sustain flight
-continuous gas exchange
Specializations of birds in the absence of teeth
- Crop: enlargement of esophagus to stir food or to transport food to nestlings
- Proventriculus: anterior stomach chamber that secreted gastric juice
- Gizzard: Posterior muscular chamber of stomach. Birds swallow gravel, sand or stones that settle in girdle and grind food
Pellets
Many birds of prey regurgitate or cast pellets with the leftovers
Pellets contain fur and bones
Reproductive strategy of birds
Oviparous
Incubate their eggs
Genetic sex determination in birds
Females are heterogametic (ZW)
Males are homogametic ( ZZ)
Female and male reproductive structures adaptation for flight
Male testes shrink outside mating season (1/300 of breeding size)
Females usually have only left ovary and oviduct
Males have no penis so males and females press cloaca together
What happens as the bird egg travels down the oviduct
- Unfertilized egg leaves the ovary to enter the oviduct. If semen is in the oviduct the egg may be fertilized there
- As egg travels down the oviduct, gland in the females oviduct secrete albumin (eggs white) which surround the yolk
- Further along, shell membrane, a lining inside the shell and then the shell itself are secreted from the shell gland in the oviduct. Pigments for the eggshell are the last thing to be secreted while the egg travels through the oviduct
- The female lays the egg through cloaca
What two main factors influence reproductive decisions
- The need for parental care
-if it’s the only way to keep them alive - The opportunity to find additional mates
-if there are lots in the area anyways…
The role of parental care for birds
-most bird nestlings are altricial (undeveloped): parents need to continually control temperature, feed, and protect
-equal ability for males and females to care (no lactation)
Biparental care
Cooperative care
Percentages in birds
82%
9%-previous years chicks that have not sexually matured, may help being up next generation.
What is the major force driving social Monogamy
The need for both parents to protect and provision the youngsters
Loose genetic input if they don’t
Social monogamy
Male and female lives as a pair during a season or life
90% of birds
Genetic monogamy
Mating exclusively within a pair
Do birds in monogamous relationships live fully monogamous?
Nope, genetic evidence shows that even if they live together and raise young together, there are chicks from different parents in the nest.
______ monogamy is much less common than _____ monogamy
Genetic
Social
Polygyny in birds
1 male with many females
-often occurs when one male can monopolize resources that attract females
-males may care for young in their territory or male not care for young in the case of precocial (developed) young who need no extra parental care. I’m these males focus all their attention on attracting more females.
Geese parental care
-precocial young
-socially monogamous
-biparental care: defend nest, find and guard food, protect chicks
Polyandry in birds
1 female and many males
-male care for young
-females attract more males
Occurs when females can increase their success by producing a lot of eggs (high predation risk areas)
Fluid mating system in Dunnocks
-females will share territory with males, but not with females
-males will share territory with other males
-with better food and resources, female territories get smaller, and 1 male may have 2-3 females on his territory (polygyny)
-with less food, female territories grow and 1 female may have 2-3 males (polyandry)
Are mating systems fixed for a species
No, depend on situations
Traditional view of bird brains compared to new view
Traditional:
-bird brains are much smaller than mammal brains
-different structure (no cerebral cortex)
-birds act by instinct, not complex cognition)
New view:
-birds have potential to provide more cognitive power per unit mass
-instead of cerebral cortex they have a pallium that integrates information
-parrots and songbirds have 2 times more neurons as a similar sized primate brain
Bird vision
-optic lobes of brain are well-developed
-eye is large, almost immobile (turn head to see)
-birds are quicker at resolving images that change quickly
-birds of prey have 2x visual acuity than humans
-have 4 cones: tetrachromatic
-sensitive to UV wavelengths
Bird hearing
-stapes (columnella) transmits vibrations from tympanum to inner ear
-large tympanum enhances sensitivity
-sensitive to pitch frequency and temporal pattern of sound similar to humans
Owl hearing
-large tympanum; large auditory centres in brain
-facial ruff acts as satellite dish, collecting and amplifying sounds
-asymmetry in left and right ear positions to help locate prey
How do birds produce sound?
Syrinx: a birds voice box, at base of trachea where it branches into bronchi to lungs
Syringes muscles control air flow from lung through syrinx, which produces sound vibrations
Can control right and left side (bronchi independently, producing two sounds simultaneously (biphonation)
To produce sound, syringes muscles contract to vibrate inner and outer walls of syrinx and to regular air flow
Migration
The relatively long-distance and usually round-trip movement of individual animals between non-overlapping home ranges. In most cases, this occurs during particular seasons of each year
Causes: food availability, climate conditions, avoid predators, breeding
What percent of worlds birds migrate?
What percent of Canadian and Arctic birds migrate?
15%
82%
Why do birds not just stay in tropics? Why go back up North?
Lower predation on young at higher latitudes and less feeding competition with other birds
Costs of migration
-energy expended during flight
-increased mortality (accidents, predation)
-anthropogenic risks are severe, especially collisions with buildings
What can be done to reduce bird-window collisions?
-covers or drawing on windows that are 5cm apart over entire window
Systems birds use to migrate
-Navigate primarily by vision: topography, landmarks, celestial cues: sun, stars.
-Magnetic compass: use beaks to measure strength of magnetic field since beaks have Iron oxide. Have pigment in retinas that are sensitive to blue light (Cry4). Magnetic compass allows birds to see magnetic fields day or night.
What two groups can aves be split into
- Paleognathae-ancient jaw. More rigid upper palate and included mostly flightless birds. Also known as ratites that have lost keeled sternum.
- Neognethae-new jaw. Includes all other birds, most of which can fly and penguins.
Paleognathae or Ratites
Characterisitcs
-flightless (no interlocking barbs or vane)
-large
-long-legs, fast runners
-can outdistance predators or attack!
Ex: ostrich, emus, tinamous (only ratite with keeled sternum and some ability to fly)
Paleognathae or Ratites
Parental care and mating style
Male-only care: males incubate eggs in oversized nest with eggs from multiple females (polygynous)
Females might move along and lay eggs in nests of other males so the females are polyandrous.
Polygyandrous meaning that makes and females have multiple partners
Biparental care seen in ostriches who both incubate eggs
Neognaths
Albatrosses, petrels and shearwaters
Characteristics
-marine birds
-long, narrow wings
-each fish, squid, crustaceans
Neognaths
Raptors characterisitcs
Raptors=birds of prey
-altricial
Hawks, eagles, vultures
-keen vision, sharp talons
Falcons
-especially fast and manueverable
-pointed wings and long tail
Owls
-nocturnal predators, large eyes, excellent hearing, silent flight
Neognaths
Waterfowl characteristics
Waterfowl=goose form
Ducks, geese and swans
-webbed feet, broad beaks
-most are herbivorous
-some eat insects, small fish, crustaceans
-ducks: dive and dabble (turn upside down)
-precocial young
Neognaths
Game birds characteristics
Quail, grouse, pheasants, turkey, peacocks
-ground nesting
-strong beaks: seeds and nuts
-precocial young
Neognaths
Terns, gulls, puffins, plovers
Characteristics
-shorebirds
-ground nesting
-string fliers
-often nest in colonies with same or different species
Neognaths
Woodpeckers, toucans, honeyguides
Characteristics
-specialized beaks
-nest in cavities
-largest species =pileated woodpecker
Neognaths
Order Passeriformes (sparrow form) known as “songbirds” or “passerines”
characteristics
60% of all birds
-feet well developed for perching on thin stems
-altricial young
-well developed syrinx
Sparrows, chickadees, robins, crows, swallows, jays
