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Orientation and navigation and true lectures


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What are the 2 "active" orientation mechanisms?
1. Echolocation
2. Electroreception
What is Echolocation?
-universal in bat and cetaceans,some mammals and birds
-like human-built sonar and radar
-animal emits a sound which bounces off objects in its patha nd echoes back
-lag time btw pulse and echo gives range
-quality of eacho: provides data on type of target
What are 3 important rules of ECHOLOCATION?
1.Resolution(smallest target that can be found) depends on wavelength (MUST Shorter than target dimension)
2.Range: depends on wavelength (longer wavelengths have greater range)
3.Time between pulse and echo:depends on target distance. (pulse frequency goes up as range decreases)
Can animals simultaneously maxmize range and resolution?
wavelength must be shorter/longer than target dimension?
longer wavelengths have greater/smaller range?
pulse frequency goes up/down as range decreases?
What are the 3 basic pulse types of bats?
3.CONSTANT FREQUENCY (pulse sweep)
Describe the FREQUENCY SWEEP of bats
-discriminate targets against background noise
-distinguishing between closely-spaced targets
Describe the CONSTANT FREQUENCY of bats
-determining the relative velocity of target (DOPPLER EFFECT)
-most CF bats also have a sweet at the end of the CF pulse
Describe Electrolocation and electroreception
-detect electric fields
-several groups of fish: have capability of producing relatively large electric fields (current-producing organs are derived from muscle tissue)
Many species use electrical pulses for communication

Some species can produc enough current to stun prey (electric eel, torpedo ray)
What are Type 1, 2, 3 orientations?
1 piloting
2.Compass sense (distance-and-direction)
3.true navigation
What is piloting?

what are the examples?
-follwing landmarks
ex.coastlines, riverside, mountain ranges, odor cues
-no sense of direction needed
-require consistent landmarks
What is "compass sense"?
finding directional cues independent of surface features
What environmental cues can serve as a compass? (3)
1.SUN:need clock(sun moves 15degrees per hour)
2.STARS:clcok needed unless orientation is based on the fixed point of rotation in the sky
3.Earth's magnetic field:lines of magnetic force always run approximately north to south (DOES NOT NEED CLOCK, Effective even if the sun or stars not visible)
Older birds were able to compensate for displacement
Which senses does Type3 (True Navigation) need?
Map sense and Compass sense
What cues can account for the map sense?
N-S and E-W position
N-S cues?
sun, stars, dip angle of magnetic force lines
Why is E-W position difficult to figure out?
there are no known, consistent E-W cues in the env.
-Humans use extremely accurate clocks to compare local time(position/motion of the sun/stars) with "home" time.
Pigeons do not use the sun's position as part of their map sense (at least for their initial flight direction)
What are other possibilities of cues?
Inertial systems(unlikely)
Infrasound(extremely low frequency sound)-produced by winds, wave...etc
Infrasound generated by the Concorde SST sonic boom can disrupt navigation in homing pigeons)
What is Migration?
movement btw PREDICTABLE SEASONAL Ranges.
-mass movement of populations in a coordinated and repeated manner
What are the costs of migration?
-usually risky (considerable mortality)
-usually N-S, some species migrate altitudinally instead of latitudinally
What are advantages of migration?
-take advantage of seasonally and spatially variable resources (if they are predictable)
food breeding sites, good weather
Why would animals leave their "safe" winter ranges (have enough food)?
to avoid competition from residents
-in evolutionary terms, migration will be favored if migrants have HIGHER REPRODUCTIVE SUCCESS than non-migrants
In evolutionary terms, migration will be favored if migrants have HIGHER REPRODUCTIVE SUCCESS than non-migrants despite risks

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