Enlighten Me: Piping plovers and coastal change
In 1986, the piping plover, a shorebird seen mostly along the Atlantic Coast and the Great Plains, was listed as threatened by the U.S. Endangered Species Act. Their numbers worldwide today are an estimated 6,000, which is why each year, during nesting season, beaches and other park areas close down to keep people from disturbing them.
As people continue to build closer to the shore, these birds face another potential threat: coastal erosion.
In this week’s Enlighten Me - Delaware Public Media’s science reporter Eli Chen examines what future might hold for piping plovers in our latest installment of iSeeChange, a project investigating the changes we see in our local environments.
Every year, around late April to early May, DNREC closes down Gordons Pond in Cape Henlopen State Park to keep people from disturbing the piping plover, a small, pale, pot-bellied shorebird that breeds and nests in low-lying sandy beaches. The breeding kind have black stripes across their forehead and necks. They’re also pretty adorable.
“The little babies when they come out, they’re precocious,” said Andrew Ednie, an avid birdwatcher from Wilmington. "As soon as they’re born, they’re able to fend for themselves and run around. They’re just so little and cute, you just can’t stand it.”
Ednie’s been watching piping plovers most of his life, starting from when his father used to take him along on surf fishing trips.
“Being a teenager, I’d get bored and wander off into the dunes,” said Ednie. “And I’d be able to find the piping plovers doing their courtship displays along the sand roads that are still around on Assateague [Island].”
That was about forty years ago.
”The birds that have been at Fenwick and Dewey Beach, they’re not there anymore,” said Ednie. “The beaches have shrunk. There’s too much recreational vehicle traffic. The birds don’t even bother using those beaches anymore.”
Now when Andrew spots piping plovers, it’s just a few at a time, not the crowds he saw when he was a teenager.
“You might one or two, nowadays,” said Ednie. “I’ve seen as much as eight. Back in the old days it was a lot easier to see them than now, that’s for sure.”
Over the years, he’s heard what many of us have: Delaware’s coastal waters are rising. Nor’easters may happen more frequently.
“I probably would ask a biologist if rising sea levels would have a permanent effect on the [piping plover.]”
Sarah Karpanty, a biologist with the Virginia Tech shorebird program, has been wondering the same thing.
“His question is a great one and we are actually trying to answer those questions and have been for some time with piping plovers.”
The Virginia Tech Shorebird Program is working on a project with the US Geological Survey and the U.S. Fish and Wildlife Service to find out whether the piping plover stands to gain or lose with rising sea levels. They study this by looking at how the birds respond to changes on barrier islands along the Atlantic Coast, already altered by both sea level rise and human development.
The piping plover’s sensitivity to humans is well known, so that's why DNREC goes out of their way to isolate whole sections of beaches from people.
“When you’re a piping plover area, if you’re a researcher or biologist, you almost tiptoe very slowly in these areas,” said Karpanty. “They are very challenging to see and it’s a pretty amazing camouflage that they have.”
This amazing camouflage also makes them easy to step on or run over with a vehicle. Piping plovers really depend on beachy areas and particularly what happens to these places after a storm hits.
“When we allow storms to happen, we often see benefits to piping plovers,” said Karpanty.
Storms create what’s called overwash, when water from the sea, carrying beach sediments, flows onto the dunes. Overwash is critical for islands to maintain their size and shape in the face of sea level rise. Karpanty says overwash is also important to piping plovers, since the chicks don’t fly for close to 30 days after hatching, so the adults have to walk with their young to forage for food.
“The best foraging areas for piping plovers are known to be on the bayside of the islands where you have these large expansive mudflats,” said Karpanty. “Those areas are actually created when storms impact an island and are allowed to overwash that island and create that kind of habitat.”
“Allowed” is the key word here. Over the time that our birdwatcher, Andrew Ednie, has grown up observing piping plovers, there’s been a lot of human development on the coast, the main driver of their habitat loss. Man-made structures built to deal with sea level rise prevent the overwash that the birds need.
“So when we build structures like jetties, sea walls, that leads to very serious declines in piping plovers,” said Karpanty.
That’s because these hardened structures keep the islands from adapting to changes in sea level rise. Evidence also shows manmade structures speed up coastal erosion. When the dunes become eroded, the post-storm mudflats aren’t created, and the piping plovers are out of a place to live.
Karpanty says it’s possible over time, the coastal storms that have helped piping plovers could become a detriment, especially if they contribute to habitat erosion. But she can’t say for sure, since there’s still a lot about sea level rise scientists don’t know yet.
“We’re just now starting to projecting into the future,” said Karpanty. “I would say in a few years we’d be more comfortable saying how some of those islands would look in the future under climate scenarios.”
Research has shown piping plovers are highly adaptable to natural changes along the shore. But the birds need the time to do it and the pace at which humans are developing the beaches isn’t helping.
“As we go forward, we need to think strategically about how sea level rise and climate will affect our coast and think about where are going to be the best areas for people and where are we going to have areas where we allow these natural coastal processes to occur and the wildlife to be able to adapt to that change,” said Karpanty.
In other words, it’s not enough to close down whole sections of beaches in the springtime. Andrew agrees there needs to be a long-term solution to protect piping plovers.
“With people building up the beaches the way they are now, it’s going to be a much bigger strain on keeping the piping plovers safe,” said Ednie. “I just think it’s fascinating that one species of bird can have so few individuals. And still be able to survive.”
Recently, the Toronto Star reported the reappearance of Great Lakes piping plovers on the Toronto Islands. They hadn’t been spotted there since June 1934, over 80 years ago.
Karpanty says these reappearances likely happen because areas that became inhospitable years ago have become ideal places to brood again. And it’s possible human efforts to protect piping plover habitats around Toronto may have helped too. But for scientists, it’s not clear yet what the future looks like for piping plovers on the Atlantic Coast and how, or if, they can adapt as seas continue to rise. However, they’re certain it’s not a bad idea for people to give the birds some room.