Tulane Researchers Looking For Environmental Clues In Mockingbirds' Songs
Elevated lead levels in the environment can cause a number of health problems for children and adults, and parts of New Orleans have consistently tested high for lead pollution.
Researchers at Tulane University are experimenting with a new way to test for lead exposure — by listening to bird songs to find out what they can tell us about heavy metals in the environment.
Tulane researcher RenataRibeiro spends a lot of time out in the field, recording the songs of Northern Mockingbirds.
“I’m an ornithologist, I study birds,” Ribeiro says. “And since I came to New Orleans, I have been fascinated by the mockingbirds. They are everywhere, they are so abundant, and they have these amazing songs that they produce. They’re called mockingbirds because they mock other birds, so they imitate the songs of other birds.”
They also imitate the sounds of the city. Ribeiro says the songs of urban mockingbirds can mimic car alarms or emergency sirens. It turns out, mockingbirds sing songs that tell researchers a lot about where the birds come from.
As Ribeiro started recording bird songs in the city, she also became aware of the very serious problem in New Orleans of lead contamination in the soil. Lead used to be used as an additive in house paint and in gasoline. Over the years, it’s built up in the environment.
“I had this idea to look at how mockingbirds may be affected by lead contamination by looking at mockingbirds in different areas of New Orleans at varying lead levels to see if their songs are different,” Ribeiro says.
The answer would give researchers another way to tell how heavy metals in the environment affect the people and animals living in it.
To start, Ribeiro needed to figure out where lead levels are high and where they’re low.
She used maps created by another Tulane public health researcher, Dr. Howard Mielke. Mielke has been mapping levels of lead in different cities around the U.S for decades.
“I've mapped the city of New Orleans,” Mielke says. “We’ve mapped the soils. The interior of the city tends to be very highly polluted with lead, and outlying areas tend to be much less polluted. “
The interior of the city, where lead levels are higher, includes neighborhoods like the Marigny and Bywater. Lakeview is an example of an outlying area with lower levels of lead. Ribeiro thinks she may find out that mockingbirds sing differently when they’ve been exposed to different levels of lead.
“Maybe mockingbirds there in the Marigny are not able to learn as many songs as mockingbirds in the Lakeview area,” she says. “Or, maybe they cannot produce the songs very consistently, like each time they repeat that particular song it’s a little different, or they can’t produce songs as fast as they should.”
And Mielke says that looking at the consequences of lead exposure on wildlife is closely connected to the health of humans. Human children exposed to high levels of lead have shown developmental and behavioral problems.
“It adds to the sense that all ecological systems are being affected by the amount of lead that has accumulated in the environment,” Mielke says. “It’s affecting many organisms, including the mockingbirds and their songs. That means it’s neurological damage in some way. It’s just a part of the subtle effect that lead has had on our living environments, especially within cities. It’s such an invisible problem to us, and to everybody, that its hard to see what needs to be done.”
He points out that in 2012, the CDC adjusted their calculation for dangerous levels of lead in the blood — From 10 micrograms per deciliter down to 5 — indicating that the effects of lead are being taken more seriously, even at very low levels. But, he cautions, it will be a long time before we will see the results of the new precautions on lead, or the new research.
Ribeiro will go out into the field with her team next month, when mockingbirds start to become active again in preparation for spring mating season. They’ll record more mockingbird songs for detailed analysis, and start capturing some of the birds to take blood samples and measure their levels of lead exposure. Connections could emerge about the consequences of pollution on wildlife.
The research team is still looking for volunteers to put bird feeders in their yards, and allow any mockingbirds that show up to be observed and tagged.
Tech and Innovation reporting on WWNO is supported by Bellwether Technology.