Flight and other locomotion in birds

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Flight and other locomotion in birds
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Lift of a wing

• Bernoulli effect pressure is inversely related
  to number of particles moving in a single
  direction (fluids).
• Newtons 3rd Law for every action there is an
  equal and opposite reaction.

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Static airfoil (wing)
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Angle of Attack
Vacuum
If angle of attack gt 5, wing starts to produce
vorticies. These can lead to stall
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Solution alula (bastard wing)

• Particularly important at low speeds and high
  angles of attack

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A
1s
Low Speed (take-off and landing) High Angle of
Attack
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• Landing

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Eoaluavis

• Sanz et al. 1996 Nature
• Eoalulavis hoyasi
• Los Hoyas, Spain
• Goldfinch sized bird
• 115mya
• 30my after Archaeopteryx
• low speeds
• high maneuverability

Florescent induced photo
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Drag

• Resistance caused by friction of air moving over
  the surface of the wing
• Induced drag occurs when the air flow separates
  from the surface of a wing
• Air moves from high to low pressures
• fills vacuums created by wing
• Profile drag is due to the friction between the
  air and bird moving through the air
• Minimized by low profile (aerodynamic anatomy)
• i.e. thin leading edge of wing

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Induced Drag

• Di - induced drag
• A - aspect ratio
• k - constant
• L - lift
• S - wing area
• Ve - airspeed
• ? - air density

High speed
Low speed
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Profile Drag
D is the force of drag, ? is the density of the
fluid, v is the velocity of the object relative
to the fluid, A is the reference area, and Cd
is the drag coefficient
D
Airspeed
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Drag Curve
aka Profile drag
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• 2 gaits of a bird
• Vortex-ring gait
• Low speeds
• Continuous-vortex gait
• High speeds

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(No Transcript)
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Flight Recap

• Amount of drag is affected by
• Body size
• Speed
• Wings surface area and shape
• Environmental factors
• Viscosity etc.

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Wing shape

• Aspect Ratio Length / width
• Range 1.5-18.0

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Gliding Wing

• Laysan Albatross

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High Speed Wing
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Explosive, Maneuverable Wing

• Grouse Wing

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• Table of Wing loading body mass / wing area

Species or group Wing-loading
Swallows 0.15
Passerines 0.2 - 0.4
Hawks 0.3 - 0.5
Waterfowl 0.8 - 1.0
Pied-billed Grebe 1.2
Loons 1.4 link
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Wing loading
low
high
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Contribution of the hindlimbs

• Varies over species
• May be very important (Starlings 80-90 of
  take-off velocity due to hindlimb contribution)

Earls 2000
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• Hummingbirds
• 46-59
• Variability depends upon motivation
• Autonomous 59
• Escape 47
• Aggressive (chasing conspecific male) 46

Tobalske et al. 2004
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The leading edge Vortex

• The LEV of a swift

Videler et al. (2004)
Low pressure zone On top of wing Wing wants to
fill the low pressure zone thereby creating
lift Can be used for maneuverability (each wing
independent)
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Wing slotting
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Different Modes of Flight

• 1. Gliding Vs/V (sinking speed horizontal
  speed)
• Glide ratio of 20
• 2. Soaring maintain altitude w/o flapping.
• Thermals (see drawing) and updrafts (slope
  soaring)
• Dynamic soaring

Obstruction lift Or slope soaring
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• Hawk mountain

east
Kettle valley
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Dynamic Soaring

• 1 - climb (windward flight)
• 2 - upper curve (change of flight direction to
  leeward)
• 3 - descent (leeward flight)
• 4 - lower curve (change of flight direction to
  windward) (Sachs 2005).

video
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3. Flapping flight

• Video of a starling in a wind-tunnel
• Downstroke (power stroke) flex wing
  depressors - lift.
• Upstroke (recovery stroke) flex wing
  elevators - minimize drag.
• Slotting

Cockatiel flying at 1m/sec
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Flapping (cont)

• Flapping is usually intermittent in small species
• And varies w/ speed

Flap-glide
Flap-bound
Budgerigars in wind-tunnel (Tobalske and Dial
1994)
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4. Hovering

• Flapping while maintaining horizontal position
• Examples

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5? Formation Flying

• Saves energy (11-14)
• Coupled with full belly even more (Kvist et al.
  2001)

low
high
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Note on metabolism and flight
Predicted
Observed
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Other forms of locomotion in birds

• Running, walking, hopping, waddling
• Head bobbing
• Ostriches
• Climbing
• Nuthatches, woodpeckers
• Swimming
• Ducks
• Diving
• Penguins, Auks