Birds observe speed limits on the roads even if motorists choose to ignore them
Scientists admitted breaking the law to carry out the study in western France
Wednesday 21 August 2013
Birds observe speed limits on the roads even if motorists choose to ignore them, a study has found.
On roads with higher speed limits, birds are quicker to take to the air to avoid on-coming traffic, but where limits are lower, they wait longer.
The behaviour is related to speed restrictions and not the result of birds assessing the speed of approaching vehicles, researchers found.
Scientists admitted breaking speed limits to carry out the study in western France.
Motoring through the French countryside in a white Peugeot hatchback, they recorded the activity of birds standing on or at the edges of roads with speed limits of 20, 50, 90 and 110 kph.
The car was driven at, under or over the speed limit and a timer used to calculate "flight initiation distance" (FID) - the closest distance the car came before the birds flew out of danger.
A total of 134 FIDs were measured for 21 species. The researchers, led by Pierre Legagneux, from Laval University in Canada, wrote in the Royal Society journal Biology Letters: "Birds had significantly higher FID on road sections with higher speed limits.
"By contrast, car speed had no significant effect on FID, both when considering absolute car speed or the difference between car speed and speed limit."
Reacting to speed limits on roads is the result of birds adapting to what they consider a "habitat characteristic", the scientists suggest.
"As road traffic directly causes mortality in birds, we expect birds to respond to road traffic in a similar way as they would respond to predation," said the researchers.
"As road mortality probably increases with speed limits we would expect individuals to adjust their anti-predator behaviour to vehicle speed and/or to the speed limit. Species with longer FID are known to have smaller risk of getting killed by cars, suggesting that adjusting FID might be an adaptive way to respond to road traffic."
They added: "Our results show that birds change their FID according to speed limit rather than car speed. This strongly suggests that birds are able to associate road sections withspeed limits as a way to assess collision risk."
Three species, the carrion crow Corvus corone, the house sparrow Passer domesticus, and the blackbird Turdus merula, accounted for more than half the study data.
FID increased with body mass, with smaller, more agile species waiting longer before taking flight.
Birds standing in the middle of the road were more cautious than those at the edges and had greater FIDs.
The study did not address bird behaviour on pelican crossings.
- 1 Tunisia hotel attack: Locals form 'human shield' to protect hotel from gunman Seifeddine Rezgui
- 2 Greece crisis: Alexis Tsipras accepts troika bailout proposals with conditions
- 3 German ethics council calls for incest between siblings to be legalised by Government
- 4 French woman dies in freak bungee jumping accident
- 5 Facebook rainbow profile pictures likely being tracked by social network
Tunisia hotel attack: Locals form 'human shield' to protect hotel from gunman Seifeddine Rezgui
Russian officials ban yoga because it's too much like a religious cult
Greece crisis: Alexis Tsipras accepts troika bailout proposals with conditions
German ethics council calls for incest between siblings to be legalised by Government
Britain First insist their videos aren't racist in bizarre attack on comedian Jason Manford
The moment a Queen's Guard soldier lost it and drew his gun at annoying tourist
Greece crisis: IMF was pushed around by Angela Merkel and Nicholas Sarkozy – and now it is being humiliated
Greece crisis: The wider lesson is that it’s time to abandon this failed experiment in currencies
'I wish the BBC would stop calling it Islamic State' – David Cameron unleashes frustration at broadcaster
Pentagon accuses Russia of 'playing with fire' over nuclear threats towards Nato
They are neither a 'state' nor 'Islamic': Why we shouldn't call them Isis, Isil or IS
£20000 - £25000 per annum: Recruitment Genius: This is an exciting opportunity...
£30000 - £35000 per annum: Recruitment Genius: This is a 3-4 month pro rata fi...
£16000 - £26000 per annum: Recruitment Genius: A Telesales Executive is requir...
£25000 per annum: Recruitment Genius: This is an exciting opportunity to join ...