Light Pollution Forms 'Eco-Traps'

"An international team of researchers has found another form of light pollution that could have an adverse effect on wildlife.

The scientists showed that as well as direct light sources, polarised light also triggered potentially dangerous changes in many species' behaviour.

They added that road surfaces and glass buildings were among the main sources of this form of light pollution.

The findings appear in Frontiers in Ecology and the Environment.

Co-author Bruce Robertson, an ecologist from Michigan State University, US, said polarised light from structures within the built environment overwhelmed natural cues that controlled animal behaviour.

"Environmental cues, such as the intensity of light, that animals use to make decisions occur at different levels of severity in the natural world," he said.

"When cues become unnaturally intense, animals can respond unnaturally strongly to them."

As a result, the false cues could create an "ecological trap" for species attracted by the light.

Dr Robertson said that water was the primary source of horizontal polarised light in the natural world, and that many animals - including birds, insects and reptiles - had highly developed polarisation vision.

This particular form of light played a key role in the animals' lifecycle, such as finding breeding and feeding sites, he added.

A well documented example is the way that baby sea turtles rely on the direction of starlight and moonlight reflected off the water's surface in order to help them find the ocean when they emerged from their nests.

Yet, there are examples of turtles in urbanised areas heading towards the brighter buildings and street lamps.

Dr Robertson said that expanding urban areas meant that there were more structures and surfaces to confuse wildlife.

"Any kind of shiny, black object - oil, solar cells, asphalt - causes problems," he explained. "The closer they are to wetlands, the bigger the problem.""

ORIGINAL SOURCE: BBC News