Noise effects on communication in song birds
Marc Naguib
Behavioural Ecology Group
Wageningen University
The 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
The main adaptations of birdsong to long range communication
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)
Grasshopper warbler
kHz
10
Song element repetition rates
8
6
4
2
0.5
1
1.5
2
s
Open habitats
Yellow hammer
kHz
Grasshopper warbler
Yellow hammer
10
8
6
10 ms
10 ms
4
2
0.5
1
1.5
2
s
Chaffinch
kHz
7
6
5
4
3
2
1
0.5
kHz
10
1
1.5
2
2.5
Wren
3
3.5
s
Woods
Chaffinch
Wren
90 ms
70 ms
5
2s
(also see Wiley 1991, Naguib 2003)
Sound degradation as distance cues
Carolina wren
Distance cues
• Reverberation
• High frequency content
• Relative amplitude
Naguib 1995, 1996, 1997
Signal structure and communication distance
Broad bandwidth
lower frequency
Amplitude
Amplitude
Narrow bandwidth
higher frequency
1
lower frequency
higher frequency
1
2
2
distance
distance
1: JND for excess attenuation
2: JND for distance difference
(after Naguib and Wiley, Anim Behav 2001)
(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
Slabbekoorn and Peet, Nature 2003
Nightingales sing louder with increasing noise levels
Brumm and Todt 2002
Indirect effects of noise on communication
From Naguib 2013
Indirect effects of noise on communication
•
•
•
•
Gene regulation
Heart rate
Immune response
Blood pressure
• Fearfulness
• Attention
• Learning
• Habitat choice
• Spatial behaviour
Do negative effects of noise result from
masking or from disturbance?
Do negative effects of noise result from
masking or from disturbance?
1. Disturb and mask
frequency
2. Disturb only
time
3. Control: empty box with no playback
Noise characteristics or animal characteristics (personality)
Field population of great tits
(Parus major)
kHz
20
1V
Personality test
(novel environment)
kHz
20
(a)
Noise playbacks during
parental care period
kHz
20
(b)
15
15
15
10
10
10
5
5
5
5s
1V
5s
1V
(c)
5s
2h playback of 60 randomly timed 1 min noise bouts
Noise Silence
Begging activity (min with calls)
Control
Disturb only
Disturb and mask
Before
During
After
Playback period
(Naguib et al 2013, Anim Behav)
Control
Begging activity
(minutes with begging calls)
Chicks beg more
when parents visit
Disturb only
Chicks beg less
during noise
Mask-and-disturb
Kind of noise does not matter
except when parents are absent
absent
present
(Naguib et al 2013, Anim Behav)
Latency to first visit in noise
Disturb only
Disturb and mask
Exploration score
(Naguib et al 2013, Anim Behav)
Relative number of visits in noise
Sexes respond in opposite ways to noise, depending on personality
0.6
Males
0.4
0.2
Females
0
0
slow
20
40
Exploration score
60
fast
(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,
Kees van Oers,
Waikato University, New Zealand
Netherlands Institute of Ecology
The Royal Dutch Academy for Arts and Sciences
Do negative effects of noise result from
masking or from disturbance?
Percent songs, call, or song switches in noise
vocalizations
MaleMale
vocalizations
100
DO
DM
*
†
90
80
Disturb only
Disturb and mask
70
60
50
40
30
20
10
0
songs in
in noise
Songs
noise
callsininnoise
noise
Calls
switchesin noise
Songsong
switches