This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Is invisibility overrated? For many species, the ability to camouflage themselves against their natural habitat provides safety from predators and other unwanted eyes. But in some ways, the opposite effect happens for the rare birds known as piping plovers (Charadrius melodus). They might actually be in better shape if more eyes saw them. Well, human eyes, anyway.
"Piping plovers are small, fairly secretive beach birds," says Walker Golder, deputy state director for the National Audubon Society in North Carolina. "They are 15 centimeters tall, the color of sand and very well hidden. Unless their nesting sites are posted, people generally don't know that they're there."
Those postings are part of the birds' protection under the U.S. Endangered Species Act. When piping plovers land on a beach to breed or feed, access to those beaches can be restricted or even closed for weeks or months at a time. Signs inform the public about the plovers' presence, but beachgoers don’t always actually see the birds. "They wonder why these areas are posted," Golder says. "They look out across the area and may not see anything because the little piping plovers are sitting on their nests." Often this misunderstanding leads to human backlash against the restrictions, which sometimes makes it even harder to protect the birds.
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Invisible or not, the tiny birds depend on the temporary protected zones for their survival. "Piping plovers cannot tolerate heavy recreational activity and chronic disturbances," Golder says. "It causes them to abandon their nests." With a total population of just 8,000 birds split between two subspecies, the loss of any nest and its eggs affects the plovers' ability to recover.
"These birds depend on beaches," Golder says. "Of course, people also like beaches. But people and birds can coexist as long as the adequate protection and management of these beaches is implemented. That doesn't mean completely and entirely excluding people from all beaches. Often you'll hear someone put in those terms—'it's either people or the birds'—and it's not that at all."
Although the public tends to hear about piping plovers most often during their critical breeding months, Golder says it is also important to protect the birds during their current southern migration—which began in July and will continue for the next month or two—and at their wintering locations in places such as South Carolina, Florida and the Bahamas. (The importance of this last site was only discovered about two years ago.) "If they migrate away from those breeding areas but don't make it back to nest there the following year, populations are going to continue to decline," he points out.
Right now most of the piping plovers have started flying south and will need to fatten up for the journey. Most of the places they stop along their migration path will feature a combination of intertidal sand flats and upland sandy beach. Here, Golder says, the birds "will rest, digest, pack on energy and pack on fat to make the next leg of their migration." The amount of time they spend foraging and the amount of food they take in during this period are essential to their survival. "It's what enables them to make the next leg of their journey or to survive a tropical storm that happens to interrupt their migration." Unfortunately, this is another time when people can accidentally disturb the plovers. "What people need to be aware of is those tiny birds scurrying along the shoreline are literally foraging for their lives," Golder adds.
Outside of disturbances the greatest threat to piping plovers has always been habitat loss. That could present new problems in the future because climate change will lead to changes in the shorelines the birds depend on, such as the impact caused by sea level rise. Ironically, the very beaches that form the plovers' habitat also serve to help humans in this case. "Many of the beaches that these birds depend on provide some protection from severe storm events, so maintaining our beaches in good, healthy conditions is certainly important," Golder notes. On the other hand, one of the biggest threats these birds and dozens of other bird species face in the future is coastal engineering, he says. The more we try to stabilize beaches by moving sand or adding immovable structures, the more the plovers' access to key habitats will be minimized.
Piping plover populations have grown since they were placed on the endangered species list back in 1986, but they have a long way to go. "Piping plovers still haven't reached recovery, and they still face huge problems," Golder says. "We have to give them the amount of space that they require and access to the habitat that they depend on." He thinks the birds and people absolutely can coexist: "We just need to give them a little room."
Photos: Piping plover by Len Blumin. Nesting sign by Aaron Knox. Both via Flickr and used under Creative Commons license