The Phantom Road

Numerous studies have documented that bird populations decline within one kilometer of a road, but what is it about roads that cause these population declines? Although many researchers have suspected that noise pollution is a significant driver of these declines, up until recently no one knew for certain.

Boise State University professor Jesse Barber is one of the leading experts on the effects of noise pollution on wildlife. He has teamed up with researchers Chris McClure and Heidi Ware to create what they call The Phantom Road. Basically, they set up a series of loudspeakers capable of reproducing road noise, without the road the itself. This is the first time that anyone has attempted to isolate the noise variable from the road to determine what effect noise only has on wildlife populations, and the results are quite startling!

The first series of results documented an overall decrease in bird abundance when the road noise was turned on, proving that the noise alone can have a negative impact on songbirds.  This research made quite a splash when it was published over a year ago, and it has awakened many within the environmental community to the importance of this issue.

The Invisible Source of Habitat Degradation

The latest publication to come out of this research documents a decrease in body condition for many of the songbird species that chose to stay in the affected area.  This means that even those birds that remained in the road noise-impacted area may have experienced a negative impact.  These birds, which under normal conditions would be listening for predators while they forage for seeds or insects, have to spend more time looking for predators when in an area affected by road noise.  This means that they are not able to forage as effectively, making it more difficult to build up the fat stores needed to continue their migration.

For a long time land managers have assumed that birds that remain in areas affected by road noise must be habituated to the sound, and are therefore unaffected.  This new research shows that there can be unseen impacts on these birds that remain in noise-affected areas – a source of habitat degradation that is invisible.

New research paper:  A phantom road experiment reveals traffic noise is an invisible source of habitat degradation

Barber Sensory Ecology Lab at Boise State University


The Phantom Road


Podcast episode featuring an interview with Phantom Road researchers Jesse Barber and Heidi Ware:

Visit the show notes page for this episode.


Phantom Road podcast part two: The Invisible Source of Habitat Degradation – with Heidi Ware and Jesse Barber:

Visit the show notes page for this episode.