Noise effects on communication in song birds Marc Naguib Behavioural Ecology Group Wageningen University The 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 Yellow hammer Chaffinch Wren Chaffinch 90 ms Wren 70 ms Grasshopper warbler10 ms Yellow hammer10 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 Amplitude higher frequency 2 Broad bandwidth lower frequency distance Amplitude 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 frequency 1. Disturb and mask Do negative effects of noise result from masking or from disturbance?

Noise characteristics or animal characteristics (personality) (a) (b) (c) Personality test (novel environment) Field population of great tits (Parus major) Noise playbacks during parental care period

NoiseSilence 2h playback of 60 randomly timed 1 min noise bouts

Playback period BeforeAfterDuring Begging activity (min with calls) Control Disturb only Disturb and mask (Naguib et al 2013, Anim Behav)

absentpresent Parent Control Disturb only Mask-and-disturb Begging activity (minutes with begging calls) 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)

Parent (Naguib et al 2013, Anim Behav) Disturb only Disturb and mask Exploration score Latency to first visit in noise

Exploration score slowfast Relative number of visits in noise 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 Zealand Kees van Oers, Netherlands Institute of Ecology The Royal Dutch Academy for Arts and Sciences

Disturb only Disturb and mask Male vocalizations Songs in noiseCalls in noiseSong switches in noise Do negative effects of noise result from masking or from disturbance?