lecture 12: bird communication Flashcards
communication
- sender sends a signal through the environment to the receiver
- the receiver then responds based on the signal
senders and receivers…
coevolve
-signal theory states that both sender and receiver need to benefit for a signal to be maintained
when sender doesn’t benefit from a signal…
it is called a cue, and because the receiver benefits they are an eavesdropper
sender benefiting from a signal, while receiver does not is know as
dishonest signal
sound is..
waves of air pressure
frequency/pitch
the number of cycles per second
-measured in hertz
wavelength
distance between wave peaks
-wavelength speed/frequency
amplitude
ie. peak amplitude, measured in decibels
Fourier analysis
- analysis of complex time series (complex sound waves) can be viewed as the sum of a bunch of sine waves
- ie. many peaks will cancel each other out, produce a flatter wave
sound production
sound waves flow around objects that are smaller than the wavelength and reflect off of bigger objects
-a sound producer has difficult making wavelengths larger than they are
why do big birds make lower-pitched sounds compared to small birds
-sounds producer generally cannot make wavelengths larger than themselves, therefore the larger the bird, the larger the wavelength
sound transmission
-the speed sound moves depends on the medium through which it moves
why do birds sing in the early morning
-sound travels slower in cold air than in hot air, due to sound refracting/bending in colder air, so it moves in a curved path to the listener, rather than a straight one as when in hotter air
sound reception/localization
-single-toned sounds are harder to locate, so alarm calls are often single toned, while mating calls have multiple tones
