It was overcast and windy on a late afternoon in late May. Robbie Fearn, Cat Bowler, and their team slipped in to their waders to prepare to head in to the marsh by Currituck Sound. It felt warm cloaked in the neoprene waders inside the lodge, but the cool ocean air made for just the right temperature outside.
Before heading out, Fearn, who directs of the Audubon North Carolina Pine Island Sanctuary, pulled up a map of the reserve's 2,600 acres and pointed to where they would be heading.
"Out into this deciduous swamp forest in here, which is right on the end of this marsh, and we'll sample in here as well," he said.
"Marshes essentially act as this big sponge. They slow down floodwaters before they can actually damage ... property and erode the shoreline."Cat Bowler
The marshes in and around the Pine Island Sanctuary serve many purposes. They trap carbon, and soak up flood waters and act as a barrier to protect coastal properties. They also house some 183 different bird species. But they are eroding due to the effects of rising seas and a changing climate. Now, the Audubon Society has embarked on a years-long surveying project to map the habitat of rare, secretive marsh birds. What they hear from the birds will serve as an indicator of what could happen to the marshes.
Bowler, who manages the Audubon’s coastal resilience program across the state, prepared the survey group. She handed out binoculars and grabbed sheets of paper to write down what birds they hear, and where they hear them.
"So if there are birds calling, we make note of that. If we see any of the species that we're surveying for, we make note of that as well," she said. "And we're also monitoring and looking around for other species that we can detect beyond those that we're surveying for."
To maintain high scientific rigor, a computer generated the 26 survey points at random, and some of them are quite difficult to access.
"On your way there you have low water. You have mud that sucks your boots off if you're not wearing waders. You have big rodents running around in the grasses around you," said Fearn. "And then the grasses are like needle rush, which are sharp and pokey. So it's a challenge."
After slogging through marsh muck for 15 minutes or more, the team set up one of the survey points. Then the listening work begins. Bowler started a recording - a 10 minute sequence. Team members stood perfectly still looking in different directions. They listened and recorded what they heard.
"You can add a Prothonotary Warbler to your list," Fearn said. "I saw it flying right there."
After five minutes of listening, the survey team plays a recording of bird calls. One every 60 seconds for five more minutes.
"And those are a series of different rails. So King Rail, Virginia Rail, the very rare Black Rail, which has recently been listed as threatened under the Endangered Species Act. And we’re also looking for Common Gallinule, and Least Bittern," Bowler said.
All of this surveying for the Black Rail and other birds isn't just a nice exercise for these ornithologists. Bowler says these marsh birds provide an early indication about the effects of climate change on the marsh.
“That's why it's important that we get out and we survey across the marsh so that we can have that landscape scale understanding of how healthy our marshes are," she said. "Which has significant implications for the communities that are located around Currituck sound."
Marshes serve as the nurseries for most of the commercially caught fish species, so the marsh benefits economies even hundreds of miles off the coast. In their more immediate proximity, marshes serve as natural infrastructure that protect coastline and coastal properties.
"Marshes essentially act as this big sponge, they slow down floodwaters before they can actually damage, you know, property and erode the shoreline," said Bowler.
A recent study published in the Proceedings of the National Academy of Sciences journal estimates that global warming has increased flood damage costs across the country by more than $2 billion per year. Protecting the natural infrastructure that protects coastal properties would save money. Fearn, the sanctuary director, says marshes also help prevent global warming in the first place.
"They actually sequester more carbon than tropical rainforests do, so the more we protect that marshes, the more we protect the atmosphere," he said. "So it all ends up being interrelated and it's critical that we pay attention to the canary in the coal mine. Because otherwise, you end up with, you know, a dead system. And we want a vibrant system."
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