1
Q
What are sound waves?
A
- pressure wave
- Here on earth, air molecules that have been set into motion by a vibrating sound source (like a bird’s syrinx) bump into each other. This creates a cascade of movement that we call a pressure wave because it moves outward in bands of increased air pressure.
2
Q
name 2 major charactersitics of sound waves
A
amplitude and frequency
3
Q
Amplitude
A
- the height of the sound waves
- energy and loudness of waves
4
Q
Frequency
A
- pitch of sound waves
- most likely looked over a period of time (duration of 1 wave cycle)
5
Q
Amplitude and frequency ROT
A
- quieter sounds have low amplitude while louder sound has higher amplitude
- lower pitch sound has wider wavelength while higher pitch sound has narrower wavelength
6
Q
Describe a spectrogram
A
- helps visualize bird sounds
- the vertical axis is the sound frequency in kilohertz, kHz
- the horizontal axis is time
- the oscillogram shows the relative loudness (typically the brighter the color, the louder the sound)
7
Q
Name the types of structural vocalizations
A
whistled vocalization and harmonic vocalizations
8
Q
Whistled vocalization
A
- Thin mostly horizontal notes, with or without harmonics
- example: white throated sparrow
9
Q
Harmonic vocalization
A
- Comprised of several frequencies produced at the same time that are multiples of each other
- Perceive a single sound with a complex tone
10
Q
What are harmonics?
A
- overtones
- series of pitches naturally produced simultaneously with a fundamental frequency
- the frequencies of a harmonic series of tones are consecutive multiples of the fundamental frequency
11
Q
What kind of nonvocal sounds do birds make?
A
- they are known as mechanical sounds, such as drumming, cracks, pops, rattling, breaks, etc.
12
Q
woodpecker mechanical sound
A
- drumrolls
- tapping
13
Q
grouse mechanical sound
A
- air-sac popping, tail quill-rattling, foot-stamping
14
Q
snipe mechanical sound
A
- drumming of snipe (air rushing between tail quills creates a pulsed sound)
15
Q
manakin mechanical sound
A
- cracks, pops, and whines produced by wings
- males get together to attract female
- screeching produced by wings rubbed together at high speeds
16
Q
hornbills
A
- twig-breaking of feeding process
17
Q
parrots and grosbeaks
A
- seed-cracking
18
Q
Function of Songs for birds
A
Long, loud vocalizations, typically delivered from an exposed perch
Identification
Mate Attraction
Territory establishment and defense
Individual fitness
(hormonally induced)
19
Q
Function for Calls of Birds
A
- important in maintenance activities
Location/contact
Individual recognition
Feeding
Aggression
20
Q
Song Repertoires
A
- Many species of songbirds: males possess repertoires of song types:
- Consist of perhaps 6 - 12 song types
- May range anywhere from 2 to an apparently unlimited number (ex. Northern Mockingbirds)
- Males in other species have just one song
21
Q
What are the possible functions of large repertoires?
A
- Each song type has a different meaning
- Advertise quality (more song types = better quality)
- Permit more effective communication with conspecific males (i.e., matching the song types of neighbors)
- Deceive conspecifics
- Prevent habituation - declining interest by females
22
Q
Song output
A
- A male in possession of a territory rich in food might be able to acquire energy more quickly than a male on a poorer territory and therefore be able to sing more actively
23
Q
song performance
A
- Differences in how songs are performed influence the ability of males to attract mates and win contests with other males
24
Q
What are alarm calls used for?
A
- can provide awareness to other members of a threat nearby
25
How can chickadees indicate an particular threat?
- Black-capped Chickadees (Poecile atricapilla) have a complex language for warning flock-mates about predators
- small species, so shows more attraction to smaller predators (larger portion for a small predator than a big one)
- the smaller the predator, the more number of D notes heard per call of the chickadee
26
Low frequency calls
- found in ground living forest species
- Interference, absorption, and scattering of the sound waves by vegetation, the ground, and the air itself progressively distort sounds as they travel
27
When are low frequency calls used?
- the most effective for long-distance communication (less subject to attenuation and interference than are high-frequency sounds)
- example: Great Tinamou
28
Forest dwelling bird songs
- Reverberations off forest vegetation can mask or degrade the fine structure of birdsongs
Tend to produce simpler sounds
- rose-breasted grosbeak
29
Open habitat bird songs
- Broadband songs rich in structure (with complex frequency modulations) are advantageous in open habitats
- Simple, sustained tones tend to be distorted by strong temperature gradients and air turbulence
- complex buzzy songs
