Chapter 8

Question 1

What are sound waves?

Answer 1

• 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.

Question 2

name 2 major charactersitics of sound waves

Answer 2

amplitude and frequency

Question 3

Amplitude

Answer 3

• the height of the sound waves
• energy and loudness of waves

Question 4

Frequency

Answer 4

• pitch of sound waves
• most likely looked over a period of time (duration of 1 wave cycle)

Question 5

Amplitude and frequency ROT

Answer 5

• quieter sounds have low amplitude while louder sound has higher amplitude
• lower pitch sound has wider wavelength while higher pitch sound has narrower wavelength

Question 6

Describe a spectrogram

Answer 6

• 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)

Question 7

Name the types of structural vocalizations

Answer 7

whistled vocalization and harmonic vocalizations

Question 8

Whistled vocalization

Answer 8

• Thin mostly horizontal notes, with or without harmonics
• example: white throated sparrow

Question 9

Harmonic vocalization

Answer 9

• Comprised of several frequencies produced at the same time that are multiples of each other
• Perceive a single sound with a complex tone

Question 10

What are harmonics?

Answer 10

• 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

Question 11

What kind of nonvocal sounds do birds make?

Answer 11

• they are known as mechanical sounds, such as drumming, cracks, pops, rattling, breaks, etc.

Question 12

woodpecker mechanical sound

Answer 12

• drumrolls
• tapping

Question 13

grouse mechanical sound

Answer 13

• air-sac popping, tail quill-rattling, foot-stamping

Question 14

snipe mechanical sound

Answer 14

• drumming of snipe (air rushing between tail quills creates a pulsed sound)

Question 15

manakin mechanical sound

Answer 15

• cracks, pops, and whines produced by wings
• males get together to attract female
• screeching produced by wings rubbed together at high speeds

Question 16

hornbills

Answer 16

• twig-breaking of feeding process

Question 17

parrots and grosbeaks

Answer 17

• seed-cracking

Question 18

Function of Songs for birds

Answer 18

Long, loud vocalizations, typically delivered from an exposed perch

Identification
Mate Attraction
Territory establishment and defense
Individual fitness
(hormonally induced)

Question 19

Function for Calls of Birds

Answer 19

• important in maintenance activities

Location/contact
Individual recognition
Feeding
Aggression

Question 20

Song Repertoires

Answer 20

• 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

Question 21

What are the possible functions of large repertoires?

Answer 21

• 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

Question 22

Song output

Answer 22

• 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

Question 23

song performance

Answer 23

• Differences in how songs are performed influence the ability of males to attract mates and win contests with other males

Question 24

What are alarm calls used for?

Answer 24

• can provide awareness to other members of a threat nearby

Question 25

How can chickadees indicate an particular threat?

Answer 25

• 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

Question 26

Low frequency calls

Answer 26

• 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

Question 27

When are low frequency calls used?

Answer 27

• the most effective for long-distance communication (less subject to attenuation and interference than are high-frequency sounds)
• example: Great Tinamou

Question 28

Forest dwelling bird songs

Answer 28

• Reverberations off forest vegetation can mask or degrade the fine structure of birdsongs
  Tend to produce simpler sounds
• rose-breasted grosbeak

Question 29

Open habitat bird songs

Answer 29

• 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