GLEN HAVEN, Mich. — Peering through a spotting scope mounted on a tripod, 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 — gray and slightly rippling on an overcast, breezy morning — 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 hospitable spots for the plump, sparrow-sized shorebirds. Conditions are worse in some places.

The Great Lakes are reaching some of their highest levels since the U.S. Army Corps of Engineers began keeping records 101 years ago. Streets, businesses and houses have flooded.

Many beaches are shrinking or submerged. For tourist-oriented businesses and waterfront homeowners accustomed to wide expanses of sand, that’s a worrisome development.

For piping plovers, it’s a mortal threat. Squeezed out of familiar turf, they move closer to places with trees and underbrush, where predators lurk, or even flee to urban areas. A pair recently took up residence on one of Chicago’s busiest Lake Michigan beaches.

“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 fluctuations happen within larger high and low periods that can last years.

But some scientists believe climate change is causing more frequent and intense shifts.