Saturday 20 December, 2014

Here’s why birds collide with man-made objects

Published On: Thu, Mar 17th, 2011 | Environment | By BioNews

Wonder why many species of bird are prone to colliding with large man-made objects? A new study outlines a new approach to understand how birds see the world and why they find pylons and turbines so hard to avoid.

Research suggests that bird mortality caused by collisions with human artifacts is the largest unintended human cause of avian fatalities worldwide.

“From a human perspective it appears very odd that birds so often collide with large objects as if they don”t see them. It is widely held that flight in birds is primarily controlled by vision, an idea captured by the phrase ”a bird is a wing guided by an eye”, said Graham Martin from Birmingham University.

“However birds live in a different visual world to humans,” said Martin.

To get a clearer understanding of how birds view the world, Martin turned to sensory ecology, a field of study, which investigates how sensory information underlies an animal’s behaviour, and it”s interactions with the environment.

The research revealed that a subtle set of interrelationships exists between a bird”s visual capacities, the interpretation of sensory information and the behaviour of birds when flying in open airspace.

“When in flight, birds may turn their heads to look down, either with the binocular field or with the lateral part of an eye”s visual field,” said Martin.

“Such behaviour results in certain species being at least temporarily blind in the direction of travel.”

Martin also explored how avian frontal vision is tuned for the detection of movement, rather than spatial detail. When a bird is hunting this detection may be more important than simply looking ahead into open airspace.

Birds also have a restricted range of flight speeds, for many birds it is simply impossible for them to fly slowly, making it difficult to adjust the rate of information they gain if visibility is reduced by rain, mist or low level lights.

A new study has been published in IBIS.

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