song and the city: avian flexibility in a noisy world

Hans SlabbekoornInstitute of Biology, Leiden University (IBL)

The Netherlands

Song and the city: Avian flexibility in a noisy world

Urbanization leads to homogenization of avian fauna

A BC C D

EFG FGC CB D

EA

Clergeau et al./McKinney et al. Biol. Cons. 2006

Urban survivors that remain and seem to thrive

Stockwell et al. 2003, after Gomulkiewicz & Holt Evolution 1999

Ecology beats Evolution

Evolution beats Ecology

High extinctionrisk

Potential importance of behavioural plasticity

Is traffic noise a factor?Which bird species do well and why?

(Foppen & Deuzeman: DLN 2007)

Road closed

Anthropogenic noise negativelyaffects reproductive success

• Male ovenbirds of noisy territorieshave 17 % lower pairing success(Habib et al. J. Appl. Ecol. 2007)

• Pairs of great tits in noisy territorieshave lower clutch size and lowernumber of fledgelings(Halfwerk et al. J. Appl. Ecol. 2011)

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Signal-to-Noise Ratio lowerhigher

Urban noise affects low frequencies most

(Nemeth & Brumm, Am.Nat. 2010)

Singing high is beneficial to urban signal range

Cuckoo Nuthatch Wren Flycatcher Tanager Thrush Ovenbird Flycatcher

(Goodwin & Shriver: Cons. Bio. 2011)

Bird occupancy in quiet (white bars) and noisy(gray bars) forest plots in Virginia (n=2 x15)

(Francis et al. Curr. Biol. 2009)

Rattlesnake Canyon, San Juan Basin in New Mexico (which has over 20,000 active oil and gas wells):

All identical with or without noisy compressor (24 hours a day, 365 days a year)

Hummer Bushtit Sparrow Finch Grosbeak Tanager Dove

(Francis et al.: PLoS ONE 2011)

Nesting

N=30

(Hu & Cardoso: Behav. Ecol. 2009)

2/3

Comparison of phylogenetically matched species groups of urban and non-urban habitat

1/3

A New/Urban/Noisy

Environment

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Impact of behavioural plasticity?

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URBAN FOREST

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Paired t-test: n=10, t=7.86, p < 0.001

Forest

Urban

Ten city-forest pairs across Europe are consistently different in frequency use

(Slabbekoorn & den Boer-Visser: Current Biology 2006)

Intra-specific variation

Time (seconds)

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kHz)

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Leiden - quiet territory

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Leiden - noisy territory

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40 45 50 55 60 65

(Slabbekoorn & Peet: Nature 2003)

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Pearson’s r = 0.377, n = 32 & p < 0.05

Noise level in dB(A)

Loud low-frequency noise correlatedto singing high in Leiden great tits

Intra-population variation

Replication of noise-dependent frequency use

Longer bouts for song types that do well under current noise conditions

(Halfwerk & Slabbekoorn, Animal Behaviour 2009)

EXPERIMENTAL EVIDENCE

(Parris & Schneider: Ecol Soc. 2009)

Not all species exhibit noise-dependent frequency use

Grey Shrike-Thrush Grey Fantail

(Ríos-Chelén et al. J. Evol. Biol. 2012)

Not all species exhibit noise-dependent frequency use

Stockwell et al. 2003, after Gomulkiewicz & Holt Evolution 1999

Ecology beats Evolution

Evolution beats Ecology

High extinction risk

But does it help? And what did they use it for anyway?

We still lack data on reproductive benefitsfor urban breeders that shift upward relative

to those that do not

Furthermore, there may be reproductive costsfor urban breeders that shift upward relative to

those that do not

Great tits sing their lower song types more often when eggs are being fertilized

(Halfwerk et al. PNAS 2011)

??

No EPC EPC

Great tit females of males that sing lower song types more often exhibit higher fidelity

(Halfwerk et al. PNAS 2011)

So, great tits may reduce masking but compromise mate attraction function

(Dabelsteen & Pedersen, Anim. Behav. 1990; Ripmeester et al. Ethology 2007)

More twitters can signal aggression

N=24 N = 27

Blackbirds sing longer twitters in cities

(Ripmeester et al. BES 2010)

Correlation between twitter use and density

= forest

= city

Habitat Territorial density

URBAN ANGER

So, blackbirds may reduce masking but may compromise motivational signalling

Summary• Urban noise can affect reproductive success

• Noise impact is frequency-dependent

• Urban birds sing higher all over the world

Ecology beats Evolution

Evolution beats Ecology

High extinction risk

• Song plasticity could save city species

• But, we need more evidence for benefits

• And, there may be costs like “Urban Anger”

Je vous remerci pour votre attention!

Margriet PeetArdie den Boer-Visser

Erwin RipmeesterWouter Halfwerk

Peter SnelderwaardHerman Berkhoudt

Carel ten Cate