Revealed: Insects change the way they communicate when drowned out by man-made noises

 

Birds and frogs do it, even whales have been known to do it. Now scientists have for the first time shown that insects also change the way they sing to one another when drowned out by man-made noises.

Click HERE to listen to a grasshopper battling traffic noise

Grasshoppers living next to a main road respond to the increased background volume of passing traffic by adjusting their summer courtship songs, scientists have discovered.

In order to make themselves heard above the low-rumble noise pollution of moving vehicles, male bow-winged grasshoppers of central Europe alter the pitch of their songs’ lower notes so that they rise to a mini-crescendo, the scientists found.

“Bow-winged grasshoppers produce songs that include low and high frequency components,” said Ulrike Lampe of the University of Bielefeld in Germany, who led the study published in the journal Functional Ecology.

“We found that grasshoppers from noisy habitats boost the volume of the lower-frequency part of their song, which makes sense since road noise can mask signals in this part of the frequency spectrum,” Dr Lampe said.

The effects of man-made noise on the sounds made by animals has been fairly well documented in vertebrates – creatures with a backbone – but has hardly been studied in the invertebrates such as insects, she said.

“We know that birds shift the frequencies of their songs or use songs with higher mean frequencies under noisy conditions. Some frog species alter their calling rate in response to high background noise levels,” Dr Lampe said.

Whales are also believed to alter their acoustic communications in response of the high-volume noises made by military submarines, ships and underwater explosions.

The bow-winged grasshopper, which is a common species in Central Europe, grows about 1.5cm long and varies in colour from green and brown to red and purple. They “sing” by rubbing a toothed file on their hind legs against the “bow” of a protruding vein in their front wings, rather like a cello.

In order to attract females during the months of July and September, adult males sing two second-long “phrases” to each song which increase in volume toward the end. Slow ticking sounds begin each phrase, which increase in speed and amplitude culminating in a buzzing sound towards the end.

Dr Lampe and her colleagues thought that the low-frequency region of the song might be masked by traffic noise which is why they decided to study the species.

“Bow-winged grasshoppers are a good model organism to study sexual selection because females can respond to male courtship songs with their own low-frequency acoustic signal, if they are attracted to a male song,” Dr Lampe said.

“Since males produce broadband signals with a maximum in the ultrasound region (above 30 kHz) and a smaller, but significant peak in the region between 6 and 10 kHz, we thought about the possibility that this lower part of the frequency spectrum might be degraded or masked by anthropogenic noise, such as traffic noise,” she explained.

The scientist collected 188 male bow-winged grasshoppers, half  from next to a busy road  and half from open grassland without any noise pollution, and compared the frequency range of their songs. They recorded nearly 1,000 different songs.

The traffic noise imposed on the urban grasshoppers could be having a serious effect on their ability to find suitable mates, Dr Lampe said.

“Increased noise levels could affect grasshopper courtship in several ways. It could prevent females from hearing male courtship songs properly, prevent females from recognising males of their own species, or impair females' ability to estimate how attractive a male is from his song,” she said.

“We don't know this, yet. We want to find out more about female preferences for spectral parameters of the songs and whether traffic noise affects these preferences in some way,” she added.

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksA special investigation by Andy McSmith
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Network Support Engineer - Hosted Telecommunications

£25000 - £30000 per annum: Recruitment Genius: This is an opportunity for a Ne...

Austen Lloyd: Private Client Solicitor / Partner - Cheltenham

Excellent Package: Austen Lloyd: A very rare high level opportunity with a fir...

Recruitment Genius: IT Manager

£30000 - £40000 per annum: Recruitment Genius: This distributor of electronics...

Recruitment Genius: Personal Assistant

£18000 per annum: Recruitment Genius: Our client has a number of different bus...

Day In a Page

HIV pill: Scientists hail discovery of 'game-changer' that cuts the risk of infection among gay men by 86%

Scientists hail daily pill that protects against HIV infection

Breakthrough in battle against global scourge – but will the NHS pay for it?
How we must adjust our lifestyles to nature: Welcome to the 'Anthropocene', the human epoch

Time to play God

Welcome to the 'Anthropocene', the human epoch where we may need to redefine nature itself
MacGyver returns, but with a difference: Handyman hero of classic 1980s TV series to be recast as a woman

MacGyver returns, but with a difference

Handyman hero of classic 1980s TV series to be recast as a woman
Tunnel renaissance: Why cities are hiding roads down in the ground

Tunnel renaissance

Why cities are hiding roads underground
'Backstreet Boys - Show 'Em What You're Made Of': An affectionate look at five middle-aged men

Boys to men

The Backstreet Boys might be middle-aged, married and have dodgy knees, but a heartfelt documentary reveals they’re not going gently into pop’s good night
Crufts 2015: Should foreign dogs be allowed to compete?

Crufts 2015

Should foreign dogs be allowed to compete?
10 best projectors

How to make your home cinema more cinematic: 10 best projectors

Want to recreate the big-screen experience in your sitting room? IndyBest sizes up gadgets to form your film-watching
Manchester City 1 Barcelona 2 player ratings: Luis Suarez? Lionel Messi? Joe Hart? Who was the star man?

Manchester City vs Barcelona player ratings

Luis Suarez? Lionel Messi? Joe Hart? Who was the star man at the Etihad?
Arsenal vs Monaco: Monaco - the making of Gunners' manager Arsene Wenger

Monaco: the making of Wenger

Jack Pitt-Brooke speaks to former players and learns the Frenchman’s man-management has always been one of his best skills
Cricket World Cup 2015: Chris Gayle - the West Indies' enigma lives up to his reputation

Chris Gayle: The West Indies' enigma

Some said the game's eternal rebel was washed up. As ever, he proved he writes the scripts by producing a blistering World Cup innings
In Ukraine a dark world of hybrid warfare and murky loyalties prevails

In Ukraine a dark world of hybrid warfare

This war in the shadows has been going on since the fall of Mr Yanukovych
'Birdman' and 'Bullets Over Broadway': Homage or plagiarism?

Homage or plagiarism?

'Birdman' shares much DNA with Woody Allen's 'Bullets Over Broadway'
Broadchurch ends as damp squib not even David Tennant can revive

A damp squib not even David Tennant can revive

Broadchurch, Series 2 finale, review
A Koi carp breeding pond, wall-mounted iPads and a bathroom with a 'wellness' shower: inside the mansion of Germany's 'Bishop of Bling'

Inside the mansion of Germany's 'Bishop of Bling'

A Koi carp breeding pond, wall-mounted iPads and a bathroom with a 'wellness' shower