Spring storms pelt piping plover populations

Spring storms pelt piping plover populations

By Lori Valigra

A SERIES OF spring storms in New England this year disrupted the annual nesting season of piping plovers and helped cause a dramatic fall-off of their populations. Just as the chicks were hatching, hungry predators like foxes and crows ravaged the birds and human intruders disturbed their nesting areas near the high dunes in the sand. The plover populations in Massachusetts and Maine both suffered their worst year on record.

Massachusetts is home to about one-third of the Atlantic coast population of piping plovers. The little birds, with dainty yellow-orange legs, a black band from eye to eye and a black ring around their neck, are a hallmark of Cape Cod beaches. But this spring's storms, heavy predation and human intrusion, proved to be a double punch for the birds making it “the worst year on record in Massachusetts in 20 years,” said Andrea Jones, director of Mass Audubon's Coastal Waterbird Program in Marshfield, Massachusetts.

In the state, populations fell to about 1.0 chicks fledged per pair of plovers in 2005 from about 1.26 the year before, according to Mass Audubon and Massachusetts Division of Fisheries and Wildlife estimates. The number of pairs of adults also declined to about 475 pairs compared to 490 pairs last year, according to Scott Melvin, a zoologist with the Massachusetts Division of Fisheries and Wildlife. Plovers lay an average of four eggs at a time, so only one-fourth of the eggs laid resulted in fledged chicks. “Based on that low productivity, we presume there will be a slight decline next year as well,” Melvin said.

In Maine, which was hit by three nasty nor'easters in the spring, the plover population fell even more dramatically. Maine Audubon says about 0.53 chicks fledged per pair, or 26 chicks fledged by 49 total pairs of birds in 2005, compared to 1.45 chicks fledged per pair, or 80 chicks per 55 pairs in 2004. That compares with 2.38 checks fledged per pair, or 95 fledglings per 40 pairs, in 1995, which was a record high.

The U.S. Fish & Wildlife Service (USFW) has taken an annual census of piping plovers since 1989, a few years after they became a protected species under the U.S. Endangered Species Act. The birds are designated as threatened along the Atlantic Coast, which means the population could keep declining if it is not protected, according to the USFW. Other species, including the U.S. federally endangered roseate tern, could benefit from the protection, as could the threatened northeastern beach tiger beetle, the least tern, the threatened seabeach amaranth, the common tern, the black skimmer and the Wilson's plover.

“Storms are a double-edged sword for plovers,” said Anne Hecht, endangered species biologist with the USFW Office of Endangered Species in Hadley, Massachusetts. Large storms can create habitat, but they also can create overwashes. So storms that occur when the birds are not nesting, such as during last year's hurricane season in North Carolina and Virginia and during Hurricane Bob in 1991, will provide plovers returning the following spring with an appealing and safe vantage point to the beach.

In Maine, three May nor'easters had the opposite effect, said Jody Jones, coordinator of Maine Audubon's Piping Plover and Least Tern Recovery Program in Falmouth, Maine. This year about 49 pairs of plovers returned to nest on Maine's beaches, 15 percent fewer than in 2004 and 29 percent fewer than the peak number of 66 nesting pairs in 2002. Fewer pairs often means fewer chicks will fledge, and this year only 26 fledglings produced by the summer, Jones said. It's been 15 years since the state's plover populations dipped below 45 fledglings.

The spring storms brought in high tides and waves that eroded dunes, washed ashore debris and destroyed plover nesting habitats. Some dunes were so eroded that they had cliff-like drops of five feet or more onto the beach. The sand spit near the Sprague River at Seawall Beach in Phippsburg, Maine, had large driftwood chunks and debris everywhere. After the storms only five of the 95 plover nests in Maine survived. Other typically productive sites like Higgins Beach in Scarborough, Maine, were bothered by predators such as crows, gulls and foxes.

Still, Maine Audubon's Jones said the plovers adapted to the changed beaches, and by early June had laid eggs that hatched in early July. That was later than usual and at a peak time for predators and for people's July 4 fireworks displays near the water.

Piping plovers were common along the Atlantic Coast during the 19th Century, but they were nearly hunted to extinction for the millinery trade.

The shorebirds typically return to the Gulf of Maine from the southern United States, West Indies and Bahamas in late March or early spring. The males establish territories near the high dunes, often decorating the nesting areas with shells and small stones to attract females, who walk up and down the line of potential homes before they select a suitor, said Jones of Mass Audubon. “The courtship dances are comical to watch. The males stomp their legs back and forth and make piping noises,” she said. The “Riverdance” type of courtship, coupled with the odds of their survival, make the birds beloved among naturalists. “What they're up against is compelling,” said Jones. “They're really exposed and vulnerable.”

In nests dug into the sand, the female lays four eggs, which hatch in about 25 days. The downy chicks soon learn to follow and mimic their parents to forage for marine worms, crustaceans and insects that they pluck from the sand. When predators or intruders approach, the young, which blend in with the sand, sit motionless while the parents try to distract the intruders by faking a broken wing. The young that survive are able to fly in about 30 days.

If the nests are disrupted by stormtides or predators before the eggs hatch, the plovers often will build a new nest in the same area. If the eggs are destroyed, they can lay eggs five or more times during the season, although the egg shells become weaker and the survival rate lower with each brood. By mid-September, the young and adult plovers fly south.

One solution to protecting nesting plovers in high-risk areas is to construct an exclosure, a protected pen area that aims to keep predators out. The exclosures usually are checked daily for any possible intrusions. Exclosures typically are constructed of 2 inch X 2 inch welded wire fence that is supported by four metal or wooden stakes. The fence enclosures are buried eight inches to 12 inches and rise 36 inches or more above the sand. The space from the nest to the fence is about five feet, creating an enclosed area about 10 feet in diameter.

But Hecht said there is a need for better exclosures. “Exclosures aren't working as well because clever foxes and crows have figured out how to get at the plovers, which become sitting targets,” she said. Foxes dig under the cages, and crows sit atop them waiting for a chick to wander close to the fence or through it.

Mass Audubon has had success this past year with some electrical fences it placed on two properties - Dead Neck, Sampson's Island in Osterville and Allens Pond Wildlife Sanctuary in Buzzards Bay. Mass Audubon's Jones said the group hopes to get funding to add three more fences next year. Mass Audubon's Coastal Waterbird Program, launched in 1987 to help stem the declining populations of piping plovers and terns in the state, has helped the populations of plovers recover from 150 pairs in 1985 to 490 in 2004. The program monitors 75 sites on the Massachusetts coastline, Buzzards Bay, Cape Cod and the Islands.

Plovers inhabit all four provinces of Atlantic Canada plus parts of Quebec, where populations have been comparatively stable because of a lack of storm activity. However, fewer adults returned this year, said Diane Amirault, wildlife biologist and an endangered species and recovery expert at the Canadian Wildlife Service in Sackville, New Brunswick. Piping plovers are protected under the Canadian Federal Species at Risk Act. Amirault said there were about 510 individual adults in 1991, but that dropped to 423 birds in 1996 and then recovered to 483 birds in 2001. The 2005 number will probably be slightly lower than in 2001, she predicted. New Brunswick has the largest population.