I’m catching up with Winged Warnings, a remarkable online series on birds as sentinels for (and victims of) environmental problems, which is unfolding over at Environmental Health News. The series launched in recent days with an introductory overview, a piece on how ospreys have recovered from the DDT era but face new ills, and a report on troubles with puffins and other northern seabirds facing disrupted food webs and a changing climate. Here’s a video summary:
The pieces are reported and edited by a remarkable team including Marla Cone and Kenneth R. Weiss. It was the latest segment, on research showing how elevated mercury levels in food distort songbirds’ calls, that caught my attention this morning via Twitter (the series hashtag is #wingedwarnings).
Here’s an excerpt, including two sound clips, from that piece, by Helen Fields and Alanna Mitchell:
Zebra finches, red-cheeked little songbirds from Australia, are used in labs as a model for vocal learning. Like humans learning to speak, they learn their songs as youngsters, starting out with babbling and gradually picking up their father’s song. Cristol’s team has used zebra finches to test a lot of the results they found in the field. Finches raised on mercury-laden food had the same nesting problems as songbirds in the field, for example.
Claire Ramos, then a postdoctoral researcher at the College of William and Mary, raised some of the finches on food containing mercury and others on uncontaminated food. Then she listened to their songs.
Ramos played a recording. “That’s a normal zebra finch. As you can tell, it’s kind of a twittery, complicated song,” Ramos said.
“And then here’s a mercury-dosed finch,” she said, playing another recording. Its song was lower-pitched, less complex. Even to the untrained ear, the bird raised on mercury-laced food sang a much different song.
Sonograms show the uncontaminated birds reached high notes of around 8 kilohertz while the mercury-fed birds’ highest notes topped out at around 6.
The fathers of those birds also ate the food tainted with mercury, since they were in the cage together. As a result, Ramos couldn’t tell if the babies were bad at learning, or if they were actually learning perfectly but the song they were learning was already garbled by their mercury-poisoned fathers.
So she did a more detailed experiment…. [Read the rest.]
I’m looking forward to a report from Alaska on the mystery of twisted bird beaks that I wrote about in 2010. I’ve been meaning to follow up and hadn’t had time.
I encourage you to explore and share this excellent work.