The Audubon Society in Connecticut is asking people to keep an eye on endangered birds at Milford Point, and coastguards say they are guarding the area.
They said the coastal flood washed away 14 nests of endangered species at Milford Point over the Memorial Day weekend.
People visiting the beach are asked to watch the signs and barriers placed to protect the birds and keep their distance.
Connecticut Audubon said the waves are overflowing the Milford Point dune and causing erosion, so the dune is smaller and there is less bird habitat. People going to the cave are asked to be more careful not to embarrass the birds and scare the herds.
Connecticut Audubon said the birds that nest in the sand dunes include Piping Plovers, American Oystercatchers, Least Terns and Common Terns, which are endangered, threatened or of particular concern in the state; and pipelines on the Atlantic coast are listed as federal endangered.
They say the Piping Plover nests are camouflaged so people walking on the beach can step on them, and those who walk too close can drive the birds out of the nests, putting them at risk of predators and the weather.
Connecticut Audubon says it takes 30 days to feed the chicks to deliver the adult tubes, during which time the kids will be safe and American fishermen, the smallest terns and ordinary terns will try to nest there as well.