Human noise affects plant, animal life

Washington, March 27 (IANS) Human noises, such as the rumble of traffic or the hum of machines, do affect birds and animals which change their behaviour accordingly, indicates a new study.

As many animals also pollinate plants or eat or disperse their seeds, human noise can have ripple effects on plants, too, says the study led by Clinton Francis of the National Evolutionary Synthesis Centre, North Carolina (US).

In cases where noise has ripple effects on long-lived plants like trees, the consequences could last for decades, even after the noise goes away, reported the journal Proceedings of the Royal Society B, citing a statement of the centre.

In previous studies, Francis and colleagues found that some animals increase in numbers near noisy sites, while others decline. But could animals' different responses to human noise have indirect effects on plants too, the researchers wondered.

To find out, the researchers conducted a series of experiments from 2007 to 2010 in the Bureau of Land Management's Rattlesnake Canyon Wildlife Area in northwestern New Mexico.

The region is home to thousands of natural gas wells, many of which are coupled with noisy compressors for extracting the gas and transporting it through pipelines. The compressors roar and rumble 24X7 round the year.

When researchers compared the number of pollinator visits at noisy and quiet sites, they found that one bird species in particular -- the black-chinned hummingbird -- made five times more visits to noisy sites than quiet ones.

"Black-chinned hummingbirds may prefer noisy sites because another bird species that preys on their nestlings, the western scrub jay, tends to avoid those areas," Francis said.

Pollen transfer was also more common in the noisy sites.

If more hummingbird visits and greater pollen transfer translates to higher seed production for the plants, the results suggest that "hummingbird-pollinated plants such as scarlet gilia may indirectly benefit from noise", Francis said.