Noise effects on communication in song birds

Marc NaguibBehavioural Ecology Group

Wageningen UniversityThe Netherlands

marc.naguib@wur.nl

Effects of noise depend on

• Signal structure

• Signal function

• Spatial characteristics

• Noise characteristics

• Individual traits

Environmental constraints on communication

Sound transmission characteristics

Environmental noise

Birds in denser habitats use lower frequencies than birds in open habitats

Birds in dense habitats use slower trills than birds in open habitats.

(Morton 1975, Sorjonen 1986, Wiley 1991)

The main adaptations of birdsong to long range communication

Grasshopper warbler

0.5 1 1.5 2 s

2

4

6

8

10

kHzYellow hammer

0.5 1 1.5 2 2.5 3 3.5 s

1

2

3

4

5

6

7

kHz

Chaffinch

0.5 1 1.5 2 s

2

4

6

8

10

kHz

2 s

5

10kHz Wren

Chaffinch 90 msWren 70 ms

Grasshopper warbler 10 msYellow hammer 10 ms

Song element repetition rates

Open habitats

Woods

(also see Wiley 1991, Naguib 2003)

Sound degradation as distance cues

Naguib 1995, 1996, 1997

Distance cues

• Reverberation• High frequency content• Relative amplitude

Carolina wren

higher frequency

lower frequency

Narrow bandwidth

(after Naguib and Wiley, Anim Behav 2001)

distance

Am

plitu

de

higher frequency

2

Broad bandwidth

lower frequency

distance

Am

plitu

de

1: JND for excess attenuation

1

2: JND for distance difference

2

1

Signal structure and communication distance

(after Brumm and Naguib, Adv. Study Behav 2009)

Noise constrains detection of:

information coded in signal distance related changes

Effects on time budgets and spacing

Urban birds change their tune

City birds sing at higher frequencies than rural birds

Nightingales sing louder with increasing noise levels

Slabbekoorn and Peet, Nature 2003

Brumm and Todt 2002

From Naguib 2013

Indirect effects of noise on communication

• Gene regulation• Heart rate• Immune response• Blood pressure

• Fearfulness• Attention• Learning

• Habitat choice• Spatial behaviour

Indirect effects of noise on communication

Do negative effects of noise result from masking or from disturbance?

3. Control: empty box with no playback

2. Disturb only

time

freq

uenc

y

1. Disturb and mask

Do negative effects of noise result from masking or from disturbance?

Noise characteristics or animal characteristics (personality)

5 s

5

10

15

20kHz

1V 5 s

5

10

15

20kHz

1V 5 s

5

10

15

20kHz

1V

(a) (b) (c)

Personality test (novel environment)

Field population of great tits (Parus major)

Noise playbacks during parental care period

Noise Silence

2h playback of 60 randomly timed 1 min noise bouts

Playback period

Before AfterDuring

Be

ggin

g a

ctiv

ity (

min

with

ca

lls)

Control

Disturb only

Disturb and mask

(Naguib et al 2013, Anim Behav)

absent present

Control

Disturb only

Mask-and-disturb

Beg

ging

act

ivity

(m

inut

es w

ith b

eggi

ng c

alls

)Chicks beg more when parents visit

Kind of noise does not matter except when parents are absent

Chicks beg less during noise

(Naguib et al 2013, Anim Behav)

(Naguib et al 2013, Anim Behav)

Disturb only

Disturb and mask

Exploration score

Late

ncy

to f

irst

visi

t in

noi

se

0 20 40 60

Exploration scoreslow fast

Rel

ativ

e nu

mbe

r of

vis

its in

noi

se

0.2

0.4

0.6

0

Females

Males

Sexes respond in opposite ways to noise, depending on personality

(Naguib et al 2013, Anim Behav)

Conclusion

• Signals evolved to reduce degradation

• Signal degradation as distance cues

• Noise can affect communication also indirectly, without masking a signal

• Response to noise can be personality-dependent

Thanks to:Joe Waas, Waikato University, New ZealandKees van Oers, Netherlands Institute of Ecology

The Royal Dutch Academy for Arts and Sciences

Male vocalizations

0

10

20

30

40

50

60

70

80

90

100

songs in noise calls in noise song switches

Per

cent

son

gs, c

all,

or s

ong

switc

hes

in n

oise

DO

DM

* †

Disturb onlyDisturb and mask

Male vocalizations

Songs in noise Calls in noise Song switches in noise

Do negative effects of noise result from masking or from disturbance?