Over the past four days, public and private officials have closed sections of Norton Point and East Beach to four-wheel-drive vehicles to protect newly hatched piping plover chicks and nests with eggs yet to hatch.

In Massachusetts, the piping plover is a threatened species. After hatching, the chicks take about 30 days before they fly, making them vulnerable to the tires of four-wheel-drive vehicles driving along a beach.

County manager E. Winn Davis said both the eastern and western ends of Norton Point Beach were closed to vehicles at 7:30 a.m. yesterday.

Mr. Davis said the western closure is aimed at protecting four piping plovers that have hatched from a nest about a half-mile east of the entrance. The closure will be in effect for at least a month.

The Wasque end of the beach was closed yesterday afternoon to protect two more nests, with eggs that had yet to hatch. Mr. Davis said he did not know how many eggs were in each nest. He anticipates the closure on the eastern end of the beach may last 45 days, which would include time for the plover chicks to hatch and fledge.

On Saturday, The Trustees of Reservations closed vehicular access on a half-mile stretch of East Beach. Trustees shorebird biologist Kate Conde said the closed stretch starts about 400 to 500 yards south of the Dike Bridge and continues to Wasque.

The closures are designed to protect four chicks that have hatched and have headed for the wrack line along East Beach, as well as three nests, each containing four eggs, elsewhere on East Beach, near Swan Pond and near Poucha Pond. Ms. Conde said she anticipates the eggs will hatch in the next four to five days.

The good news for four-wheel-drive beach-goers this year is that the plovers have placed all their nests south of the Dike Bridge, leaving all of Cape Pogue open to vehicular traffic.

Another nest, with an undetermined number of eggs, has been found on State Beach, which the county manages for the state. Although four-wheel-drive vehicles are not allowed on that beach, Mr. Davis said steps will be taken to protect the nest from pedestrian traffic.