“How to Give a Seabird an Underwater Hearing Test”
by Ashley Braun
Hakai, August 25, 2016
The world’s coasts are becoming increasingly noisy—ringing, clanging, and whirring with the sounds of renewable energy projects, coastal construction, offshore drilling, commercial shipping, and more. While a great deal of effort has been directed at measuring how this cacophonous chorus may be affecting whales, dolphins, seals, and even fish, one notable group of marine life has been left out entirely: seabirds.
Yet a northern gannet plummeting beneath the waves chasing fish may be subject to the same acoustic disruptions as a hunting harbor seal.
“A lot this research has been done with marine mammals and fish already to show what type of behavioral impacts noise might have or physiological impacts,” researcher Sara Crowell told me, “but there really is none on birds. Birds are subject to the same pressures that marine mammals and fish are.”
But before Crowell’s colleagues at the U.S. Geological Survey Patuxent Wildlife Research Center in Maryland can answer how undersea noise might be affecting seabirds, they first have to grapple with a much more basic question: How do you perform a hearing test on a seabird above water, much less below water?
I propose a news story for Hakai that would highlight how seabirds have been left out of underwater noise considerations and wildlife management guidelines and explore the two ways researchers are testing seabird hearing so far to get the answers they need to fill in these gaps.
The first is known as auditory brainstem response and is the typical, quick and easy hearing test most human babies receive right after birth. A second, more definitive—but difficult to pull off—method uses behavioral training. This approach requires months of training the animals to peck at a target, either above or underwater, when they hear different tones.
This team has begun publishing baseline hearing levels for a range of seabirds, for the first time, and has a forthcoming paper exploring their efforts to use behavioral training to test the hearing
of the USGS research center’s captive seabird colony. The next step is adapting this method to conditions underwater, which is also in the pipeline this fall.