noise effects on communication in song birds marc naguib behavioural ecology group wageningen...
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Noise effects on communication in song birds
Marc NaguibBehavioural Ecology Group
Wageningen UniversityThe Netherlands
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?