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Modern Birds

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Title: Modern Birds


1
Modern Birds
  • The other remaining Archosaurs are birds given
    their own class Aves by traditional taxonomists.
  • There are approximately 8,600 species of birds
    ranging is size from the tiny bee hummingbird to
    the ostrich.

2
Bee hummingbird http//images.encarta.msn.com/xre
fmedia/sharemed/targets/ images/pho/t172/T172726A.
jpg
http//www.hedweb.com/animimag/ostrich-hotlinks.jp
g
3
Characteristics of the birds
  • Feathers a unique character among living animals,
    but also found in dinosaurs.
  • Endothermic
  • Skeleton modified for flight. Bones hollow,
    forelimbs support the wing, ribs with uncinate
    processes, beak but no teeth, reduced tail.
  • Breathing by lungs and associated air sacs
  • Internal fertilization and hard-shelled amniotic
    egg

4
Evolution of birds
  • Birds evolved from a group of theropod dinosaurs
    in the Jurassic period. The oldest known bird
    fossil is Archaeopteryx lithographica which has a
    mix of reptilian and avian features.
  • Reptilian long tail, teeth, long clawed fingers
  • Avian feathers, ribs with uncinate processes,
    avian shoulder girdle.

5
Archaeopteryx (oldest known fossil bird) Jurassic
150mya
6
(No Transcript)
7
Feathers
  • Among living animals feathers are a uniquely
    avian trait.
  • However, it is now well established that feathers
    also occurred in dinosaurs. In the 1990s
    feathers were described from series of non-avian
    coelurosaurs, mostly from the Chinese Liaoning
    deposits.

8
Feathers
  • Feathers are what enable birds to fly, but
    originally are believed to have evolved as a
    thermoregulatory device.
  • Feathers are lightweight, but strong. The
    surface of the feather is made up of tightly
    spaced, overlapping filaments that hook together.
    Overlapping feathers form the wings with which
    birds fly.

9
Dinosaur feather impressions
10
Feather structure
  • Feathers are made of keratin an inert substance
    that consists of insoluble microscopic filaments
    embedded in a protein matrix.
  • Keratin is the substance found in hair, nails,
    claws and scales of other animals, but bird
    keratin is unique and differs from that of modern
    reptiles.

11
Feathers
  • There are two main categories of feathers
  • Plumaceous downy for insulation
  • Pennaceous linked , vaned feathers wing and
    contour feathers.
  • Vane of a typical body feather consists of a
    hidden downy base (for insulation) and an exposed
    cohesive outer portion (for streamlining).

12
Downy Feather http//farm1.static.flickr.com/21/33
309716_ad54e344dd.jpg?v0
13
Feathers
  • Body feathers of most birds include an aftershaft
    that emerges from the underside of the shaft
    where the first basal barbs of the vane branch
    off.
  • The aftershaft is almost always downy and
    functions to increase insulation. In ptarmigan
    winter plumage the aftershaft is ¾ as long as the
    main feather.

14
Aftershaft http//strategis.ic.gc.ca/pics/cp/feath
er-e.gif
Ptarmigan http//fwp.mt.gov/mtoutdoors/images/Por
traits/Ptarmigan.jpg
15
Feather structure
  • A contour feather has a long central shaft and a
    broad flat vane. The hollow base of the shaft
    (quill) anchors the feather in a follicle under
    the surface of the skin.
  • The rest of the shaft, the rachis, supports the
    vanes. Branching off from the rachis are barbs.
    Each barb has barbules projecting to either side
    that interlock with the barbules of adjacent
    barbs.
  • Barbs and barbules form an interlocking, but
    flexible surface.

16
19.4
17
Adaptations for flight
  • In general, the avian skeleton has been lightened
    and strengthened for flight.
  • This has been achieved by eliminating some
    structures and modifying others.

18
Adaptations for flight
  • Feathered wing.
  • Mass reduction
  • Wrist bones reduced to two
  • Bones hollow and supported by internal struts or
    spongy bone
  • Reptilian tail lost. Fused tail bones (pygostyle)
    support tail feathers
  • Teeth lost. Skull and bill light but strong.

19
19.6
20
Adaptations for flight
  • Skeleton strengthened
  • ribs have rear-facing uncinate processes that
    overlap and strengthen walls of thorax
  • bones of wrist, pelvis fused
  • Sternum or breastbone enlarged with a large keel
    (carina) for attachment of massive flight muscles
    -- pectoralis and supracoracoideus.
  • Fused hand bones support and maneuver primary
    flight feathers.
  • Efficient lungs and powerful four-chambered heart
    power flight.

21
http//www.birdwatching-bliss.com/images/bird_skel
eton.jpg
22
Further skeletal modifications for flight
Triosseal canal
  • Trisosseal canal. The triosseal canal is formed
    by the junction of the coracoid, scapula and
    furcula. The supracoracoideus tendon passes
    through this canal up from the supracoracoideus
    and inserts on the dorsal face of the humerus.
  • Dorsal insertion allows triosseal canal to act as
    a pulley and the supracoracoideus can lift the
    wing during the recovery stroke.

23
Triosseal Canal. http//www.palaeos.com/Vertebrat
es/Units/350Aves/Images/Aves2.gif
24
Further skeletal modifications for flight
Triosseal canal
  • If the supracoracoideus tendon is cut a bird
    cannot takeoff because the supracoracoideus
    muscles are required for the initial rapid
    wingbeats necessary to get a bird off the ground.
  • Once airborne a bird with severed
    supracoracoideus tendons can fly because the
    dorsal elevator muscles are capable of raising
    the wing on the recovery stroke.

25
Further skeletal modifications for flight
  • Furcula The clavicles are fused to form a
    structure called the furcula or wishbone.
  • The furcula flexs during flight and spreads and
    contracts during each wingbeat. The flexing may
    enhance gas exchange by assisting in moving air
    through the air sacs.

26
Furcula (in red)
http//upload.wikimedia.org/wikipedia/commons/6/6e
/Furcula.png
27
Further skeletal modifications for flight arm
and fingers
  • The wing is supported by the arm and finger
    bones. There are three remaining fingers. The
    fused hand and finger bones provide strength and
    rigidity in the outer wing skeleton.
  • The primary feathers attach to the wrist and
    finger bones, while the secondaries attach to the
    radius and ulna. The first digit (the thumb if
    birds had one) controls the alula or bastard
    wing.
  • The alula is a flap that is important in
    maintaining a smooth flow of air over the wing at
    low speeds (it helps prevent stalling).

28
http//www.dkimages.com/discover/previews/1244/950
05058.JPG
29
Bernoullis Principle
  • A birds wing is an airfoil and is cambered with
    a slightly convex upper surface and concave under
    surface.
  • Because air must travel further over the upper
    surface of the wing than below it must travel
    faster and thus exerts less pressure above the
    wing than it does below.
  • The increased pressure below generates lift, the
    force which keeps the bird up.

30
19.13
31
Lift and thrust
  • In order to fly both horizontal thrust and
    vertical lift are required.
  • Thrust is mainly generated by the primary
    feathers (the long ones at the end of the birds
    hand), which on the downstroke twist and acting
    like a propeller push the air backwards.
  • Lift is mainly generated by the secondary
    feathers (the inner portion of the wing), which
    form an airfoil.

32
http//www.dkimages.com/discover/previews/981/5039
2155.JPG
33
Arrangement of feathers http//www.birdsnways.com/
wisdom/imgs/wingsm.gif
34
Structure of hindlimbs
  • Legs joints and bones. When looking at a birds
    leg what appears to be the knee is not. It is
    the ankle.
  • The knee joint is hidden by feathers. The long
    bone leading from the toes is the tarsometatarsus
    (from tarsals and metatarsals) and above that is
    the tibiotarsus

35
http//www.palaeos.com/Vertebrates/Lists/Glossary/
Images/Hypotarsus.gif
36
Perching
  • Being able to perch in trees was an early avian
    adaptation.
  • The largest group of birds the Passerines
    (Passeriformes perching birds) have four
    moderately long toes, three facing forward and
    one back.
  • The tendons of the toes can lock the foot in a
    firm grip. Hence a sleeping bird does not fall
    off its perch.

37
Perching Song Thrush http//www.bbc.co.uk/cumbria/
content/images/2008/02/13/ bird_blue_sky_353x470_3
34x470.jpg
38
Hopping and walking
  • Most passerines hop and in fact most cannot walk.
    However, some species that spend a lot of time
    on the ground such as larks and starlings can
    walk.
  • In many other groups of ground-dwelling birds
    (e.g. chickens and their relatives) however
    walking is used.

39
Running
  • A few birds are specialized for running and
    possess long legs.
  • The most obvious are the ostrich and relatives.
    As is the case in horses the number of toes has
    been reduced to reduce mass at the end of the
    limb. Ostriches have two toes and rheas three.

40
Ostrich foot http//lh5.ggpht.com/_jfN-xAu1BR4/ R
so0OBjqMjI/AAAAAAAAAS0/jS4eZws8GkY/ZooTrip019.jp
g
41
Climbing
  • Various birds including woodpeckers, nuthatches,
    treecreepers and woodcreepers climb up and down
    tree trunks.
  • The feet in all cases are strong and the toes
    usually well curved and the tail is often used as
    a brace to prop the body against the trunk.

42
Montane Woodcreeper http//www.birdsinperu.com/ima
ges/ fotos20aves/Montane-Woodcreeper.jpg
Bennetts Woodpecker http//www.exzooberance.com/v
irtual20zoo/they20fly/woodpecker/ Bennetts20Woo
dpecker20268072.jpg
43
Swimming
  • A wide variety of birds swim and webbing of the
    front three toes has evolved independently at
    least four times and all four toes are connected
    by webbing in the pelicans and cormorants.
  • The other adaptation to increase surface area for
    swimming is lobed toes.

44
Pelican Feet http//farm1.static.flickr.com/179/47
6653597_bbd825c035.jpg?v0
45
Coot Feet http//jrcompton.com/photos/The_Birds/J/
Jan_07/_JR58714-coot-lobed-feet.jpg
46
Avian lung
  • The metabolic demands of flight are high and to
    meet these demands the avian lung must be much
    more efficient than the mammalian lung.
  • In birds the finest branches of the bronchi do
    not end is saclike alveoli. Instead they form
    tubelike parabronchi through which air flows in
    only one direction (in contrast to the tidal flow
    in mammals). Because the air flow is one-way,
    gases can be more efficiently exchanged and there
    is no dead air in the lungs

47
(No Transcript)
48
Avian lungs
  • The one-way flow of air is achieved by using a
    system of air sacs and a two breath cycle.
  • On inspiration a bolus of air flows down the
    trachea to air sacs below the lung. On
    expiration the air mass flows into the lung where
    gas exchange takes place.
  • With a second inspiration the air mass in the
    lung flows into anterior airsacs and with a
    second expiration exits the body via the trachea.

49
19.10
50
Feeding and digestion beaks
  • Birds are not the only organisms with beaks as
    turtles and various dinosaurs possessed them too.
  • However, birds have a tremendous diversity of
    beaks.
  • The beak is a birds principal tool for handling
    food and its size and shape determine the foods
    that can be eaten.

51
Beaks
  • Birds such as crows and ravens have a general
    purpose bill that can handle lots of different
    foods.
  • Warblers have fine forceps like bills good for
    handling soft-bodied foods such as insects.
  • Finches possess short, deep bills that are ideal
    for opening seeds. Crossbills have beaks in
    which the upper and lower mandibles cross.
  • These are ideal for opening pine cones to reach
    the seeds

52
Raven http//www.neothera.com /jpegs/raven.jpg
53
Magnolia Warbler http//www.hiltonpond.org/images
/WarblerMagnoliaM03.jpg
54
House Finch http//www.critterlight.com/House-Finc
h-6-063003.jpg
55
Crossbill beak http//newsimg.bbc.co.uk/media/imag
es/41436000/ jpg/_41436817_malecrossbill203rspb.jp
g
56
Beaks
  • Dabbling ducks, such as mallards, have beaks that
    are good for straining water. However, ducks
    such as mergansers have beaks that are serrated
    and help in grasping fish.
  • Spoonbills and flamingoes possess bills similar
    to dabbling ducks that are good for sifting mud
    and water.

57
Common Merganser http//library.thinkquest.org/ T
Q0310822/images/Common_merganser.jpg
Merganser beak http//www.learner.org/jnorth/image
s/graphics/a-b/Beak-Merganser.jpg
58
Flamingo beak http//spot.colorado.edu/humphrey/f
act20sheets/ flamingo_caribbean/images/flamingo_h
ead.gif
59
Beaks
  • Raptors, such as owls, hawks and eagles, possess
    short bills with a hooked tip that are ideal for
    dismembering prey.

60
Ferrunginous Hawk http//www.photographytips.com/i
mages/rhonda-spencer-ferruginous-hawk.jpg
61
Beaks
  • Toucans and hornbills are both fruit specialists
    and their light, but long bills allow them to
    pluck distant fruit.

62
Keel-billed Toucan http//www.sottm.com/Toucan.jpg
Great Hornbill http//khaoyai.files.wordpress.com
/2008/01/hornbill_013.jpg
63
Beaks
  • Among the more unusual beaks is the beak of the
    skimmer a relative of the gulls and terns.
  • In skimmers the lower mandible is laterally
    compressed and the bird flies over the water with
    the lower mandible skimming through the water.
    When the beak hits a fish, it snaps shut
    immediately on it.

64
Black Skimmer http//i.pbase.com/v3/88/57088/1/466
67287.black_skimmer.jpg
65
Feeding and digestion
  • Because birds lack teeth they cant process food
    much in the mouth so that is left up to the
    gastric system.
  • Birds can frequently gather food faster than it
    can be processed. This food is usually stored in
    the birds crop, an enlarged part of the
    esophagus.
  • The crop is also used to store food that will
    later be regurgitated to chicks.

66
Birds digestive tract and other internal
organs http//www.dkimages.com/discover/previews/8
24/80016755.JPG
67
Hoatzin
  • One South American bird, the Hoatzin is an
    obligate leaf eater and this is the only bird
    that uses its crop as a fermentation chamber.
  • Hoatzins are also unusual because their chicks
    possess claws on their wings, which they use to
    scramble around in the branches. The claws are
    later lost.

68
Adult Hoatzin http//www.rarespecies.org/hoatzin.j
pg
http//3.bp.blogspot.com/_E87qS3OzVLQ/SdP3gaOsBZI/
AAAAAAAAD3E/3fjXx4nJ4ak/s200/Hoatzin_chick_w_claw
s.jpg
69
Stomach
  • The stomach a birds possesses is dictated by its
    diet. Birds that each high volumes of soft foods
    such as meat have extensible stomachs that can
    hold a lot of food.
  • Those that have to process tough foods such as
    seeds and insects have much more muscular
    stomachs that help to grind the food.

70
Stomach
  • A birds stomach has two parts the anterior
    glandular proventriculus and the posterior
    gizzard.
  • The proventriculus contains glands that secrete
    digestive enzymes. In birds that swallow whole
    foods such as fruits the proventriculus is often
    very large.

71
Gizzard
  • The gizzards main function is to mechanically
    process food.
  • The walls of the gizzard are thick and muscular
    and the gizzard often contains small stones,
    which the birds swallow to assist in grinding the
    food. The gizzard thus fulfills the same role as
    the teeth in mammals.

72
Gizzard
  • The gizzard can exert significant pressure. For
    example, a turkeys gizzard can process two dozen
    walnuts in about four hours.
  • It can also crack hickory nuts, which require
    50-150kg of pressure to break.

73
Intestines
  • The main site of chemical digestion is the
    intestine where enzymes break down the food into
    small molecules that can be absorbed across the
    intestinal wall.

74
Seasonal changes in gut morphology
  • Birds often change their diets over the course of
    a year and gut morphology changes too. Insects
    are more easily and quickly digested than plant
    food (e.g. berries).
  • When starlings switch to eating more plant
    material in the fall their intestines increase in
    length by about 20 and decrease by a similar
    amount in spring when their diet switches back to
    animal prey.
  • Accompanying the morphological changes are
    changes in the types and quantities of digestive
    enzymes produced tailored to match the
    composition of the diet.

75
Sensory systems vision
  • Most birds have excellent vision and this is
    reflected in the structure of the brain. There
    are large optic lobes and the midbrain which
    processes visual information is enlarged.
  • In contrast, in most birds olfaction is
    unimportant and the olfactory bulbs are small.

76
Puerto Rican Screech owl http//www.fs.fed.us/r8/c
aribbean/wildlife-facts/2003/ wildlife-facts_image
s_2003/pr_screech_owl.jpg
77
Vision
  • Birds have very large eyes so much so that the
    brain is up and back in the skull to accommodate
    them.
  • Bird eyes are similar in structure to those of
    other vertebrates, but the shape varies from a
    flattened sphere to tube-like.
  • The variation is shape appears to be a result of
    the difficulties of fitting an enlarged eye into
    a more modest sized skull. By altering eye shape
    birds such as owls have avoided developing the
    disproportionately large heads they would have
    required if the eye were spherical.

78
  • A unique feature of the avian eye is the presence
    of a comb-like structure called the pecten.
  • The pecten arises from the rear of the eye close
    to where the optic nerve exits the eye.
  • The function of the pecten remains unclear even
    after 200 years of investigation. The organs
    large blood supply suggests it may provide
    nutrition to the retina and perhaps remove
    metabolic wastes from the vitreous humor.

79
Vision
  • A second interesting feature of avian eyes is the
    presence of colored oil droplets in cone cells.
  • These act as filters absorbing certain
    wavelengths of light and allowing others through,
    but their exact function remains unclear.

80
Hearing
  • Birds have hearing that is comparable in
    sensitivity to that of humans even though their
    heads are much smaller.
  • However, they have proportionally much larger
    tympanic membranes which enhances sensitivity to
    sound. In addition, the cochlea has about 10x as
    many hair cells per unit length than a mammalian
    cochlea does.

81
Hearing
  • Owls possess the most acute hearing among birds
    (comparable to that of a cat) and can isolate
    sounds very accurately even in complete darkness.
  • Owls possess a distinctive facial ruff of stiff
    feathers that acts as a parabolic sound
    reflector, which focuses and amplifies sounds.
  • Some ruffs are asymmetric and the ruffs
    asymmetry (as well as asymmetry in the vertical
    placement of the ears) enhances the owls ability
    to isolate sounds in three dimensional space.

82
Barn owl http//www.usbr.gov/mp/ccao/ newmelones/i
mages/wildlife_barn_owl.jpg
83
Hearing
  • The asymmetries in the ruff and ears cause delays
    in the time at which sounds reach each ear that
    can be interpreted by the brain and used to
    identify precisely the source of a sound.
  • A barn owls ability to do this is so good that
    it can isolate sound to within 1º in three
    dimensional space. If you envisioned yourself
    surrounded by a sphere with a radius
    approximately equal to your arm length 1º would
    be about the area covered by a fingertip.

84
Olfaction
  • Most birds have a poorly developed sense of
    smell, but a few groups do have a good sense of
    smell.
  • These include kiwis which have their nostrils at
    the end of the bill and use odor cues to find
    prey when they probe in the earth.

85
Brown Kiwi hatched at the Smithsonina National
Zoo 2006 http//news.nationalgeographic.com/news/
2006/02/images/060217_kiwi.jpg
86
Olfaction
  • Other birds with a good sense of smell are the
    various tubenoses the petrels, shearwaters and
    albatrosses, which are attracted to the scent of
    chummed fish and fish from a considerable
    distance.
  • In addition, turkey vultures have a well
    developed sense of smell and can find even
    covered carcasses very quickly.

87
http//www.wildland.com/trips/details/Images/anf_a
lbatross_b.jpg
88
Turkey Vulture http//www.lakesidenaturecenter.or
g/images/ AC_Turkey20Vulture20Head20Shot20from
20MDC.jpg
89
Diversity of birds major bird orders
  • Struthioniformes Ostriches, rheas, cassowaries
  • Podicipediformes Grebes (diving birds with
    lobed feet). 21 species.
  • Gaviiformes Loons. 5 species.
  • Pelecaniformes. Pelicans and cormorants. 67
    species.

90
Southern Cassowary http//www.daintreebirdwatching
.com.au/images/cassowary-Robert20South3.jpg
91
Pied-billed Grebe http//www.geometer.org/TT2004/
Florida/images/Grebe.jpg
Common Loon http//www.freewebs.com/swiv/common-lo
on.jpg
92
Great Cormorant http//www.kenyabirds.org.uk/pics/
great_cormorant.jpg
93
Diversity of birds major bird orders
  • Anseriformes Waterfowl. Ducks, geese and
    swans. About 160 species.
  • Falconiformes Hawks, eagles and falcons. Over
    300 species
  • Galliformes chicken-like birds. Grouse, quail,
    turkeys. Over 250 species.

94
Ruffed Grouse http//sdakotabirds.com/species/phot
os/ruffed_grouse.jpg
95
Diversity of birds major bird orders
  • Ciconiiformes Long-legged wading birds.
    Storks, herons, ibises, egrets. 120 species.
  • Charadriiformes Shorebirds and gulls. Plovers,
    sandpipers, stilts, auk, puffins, gulls and
    terns. Over 360 species.
  • Columbiformes Pigeons and doves. Over 300
    species.
  • Psittaciformes Parrots. More than 350 species

96
Razorbill (auk) http//media-2.web.britannica.com/
eb-media/16/26016-004-13D8FA4C.jpg
White Stork http//susty.com/image/stork-long-oran
ge-legs- beak-white-feathers-black-plumage-stand-s
leeping-green-vegetation-photo.jpg
97
Rock Dove http//www.astro.umd.edu/dcr/Archives/P
hotos/Birds/filenames/Pigeon,Feral.jpg
98
Scarlet Macaw http//animalsneedkisses.files. word
press.com/2009/03/parrot.jpg
http//creagrus.home.montereybay.com/Parrot-BN_MR7
817-w.jpg
99
Diversity of birds major bird orders
  • Strigiformes Owls. About 180 species.
  • Apodiformes Short-legged acrobatic fliers.
    Swifts and hummingbirds. About 420 species.
  • Piciformes Woodpeckers. About 400 species.

100
Common Swift http//www.naturephoto-cz.com/photos/
birds/common-swift-3629.jpg
101
Diversity of birds major bird orders
  • Passeriformes Perching birds. Songbirds.
    Crows, warblers, cardinals, sparrows, starlings,
    etc. Over 5,700 species.

102
Cardinal http//2.bp.blogspot.com/_-cBb578jsLk/ Rm
P1nuxW8II/AAAAAAAAAHM/SCIyggloewY/ s400/cardinal.j
pg
European Starling http//rightofmiddle.files.wordp
ress.com/2009/01/european-starling.jpg
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