A piping plover walks last week in the area sectioned off for the endangered species on Montrose Beach, Illinois. The shorebirds, which are endangered in the Great Lakes, are at greater risk because of rising water in the area. (Ashlee Rezin/AP)

Peering through a spotting scope, researcher Alice Van Zoeren notices a piping plover skittering across a sandy, pebble-strewn Lake Michigan beach and hopping into a nest, swapping places with its mate.

“Nest exchange! Did you see it?” Van Zoeren calls to colleagues. Male and female plovers take turns incubating their eggs, and this pair’s flawless changing of the guard is a healthy sign.

Yet trouble is brewing for them — and for other piping plovers, already one of the Great Lakes region’s most endangered species — as water levels surge during a rain-soaked spring that has flooded large areas of the Midwest.

Pools are forming behind several nests along this beach at Michigan’s Sleeping Bear Dunes National Lakeshore. And the big lake has crept within a few yards of the plovers’ nesting zone.

Their home could be one storm away from destruction. And this is one of the most better spots for the plump, sparrow-size shorebirds.

The Great Lakes are reaching some of their highest levels since the U.S. Army Corps of Engineers began keeping records 101 years ago. Many beaches are shrinking or are underwater.

A sign warns visitors of a piping plover nesting area in Glen Haven, Michigan. (John Flesher/AP)

For piping plovers, it’s a deadly threat. Squeezed out of familiar turf, they move closer to places with trees and underbrush, where predators lurk.

“The high water levels really put them in danger more than most other species because their habitat has been greatly diminished,” said Vince Cavalieri, piping plover coordinator for the U.S. Fish and Wildlife Service. Some nests on the Canadian side of the lakes have been swept away, he said.

The Great Lakes generally rise with the snowmelt and rainstorms of spring and dip during later dry spells. Those minor changes happen within larger high and low periods that can last years.

But some scientists believe climate change is causing more frequent and intense shifts. Lakes Huron and Michigan hit record low levels in 2013 during a lengthy slump. An abrupt turnaround followed. Bitter winters froze lake surfaces and limited evaporation, while snowfall and spring downpours got heavier. As parts of the nation’s midsection flooded this year, the lakes filled to the brim.

University of Michigan hydrologist Drew Gronewold and climate scientist Richard Rood concluded in a recent article that “rapid transitions between extreme high and low water levels in the Great Lakes represent the ‘new normal.’”

If so, the piping plovers’ situation could become more dangerous. Their numbers have dropped sharply with shoreline development. The federal government lists them as threatened in the northern Great Plains and along the Atlantic coast, where rising sea levels put their wintering grounds at risk. But the Great Lakes population is endangered, hitting a low of just 12 breeding pairs in 1990.

Piping plovers build their nests along the beach. This year some of Lake Michigan’s beaches are underwater. (Steven Senne/AP)

Recovery projects are helping; 76 pairs were counted in 2017 and 67 last year. This year’s census is underway but expected to yield similar results, said Cavalieri of the Fish and Wildlife Service.

The next few weeks are crucial. Most of this year’s eggs will hatch by the end of June. If additional storms don’t wash away nests, a new batch of youngsters may survive.

But long-term prospects will be dicey until the waters recede.

Piping plovers are a migratory species, breeding during summers in the northern United States and Canada, and heading south to winter in coastal areas from the Carolinas to Texas.

Even if the birds aren’t flooded out, the rising waters make their lives harder.

“It’s forcing them to use the same areas as birds they might not be used to neighboring with,” Adams said. “That increases competition, especially for the chicks that hatch this year. If they don’t have enough food, enough space to forage, they won’t have enough calories to make the journey down south.”