Nature Notes: By Way of the Land Bridge
Biogeography is the study of flora and fauna and how they got where they are today. It also applies to humans. We are pretty sure that Asians began to settle North America not quite 20,000 years ago when glaciers covered half of the northern hemisphere and sea level was 100 feet or so lower than today. Many, if not all, came by way of the “land bridge,” now submerged, between Siberia and Alaska. Many mammals and other vertebrates came to the Americas by the same route.
On a very local level, Long Island has had several land bridges by which fauna and flora moved from the south to the north. The barrier islands once ran all the way to Amagansett. Remnants remain today, including the beaches between Hook Pond and Georgica Pond and from Wainscott Pond all the way to Agawam Pond in Southampton Village, interrupted along the way by several ponds. East of Shinnecock Bay, these former barrier islands have moved onshore and merged with the mainland. Fire Island and its extensions to the east and west are still largely intact and separated from the mainland by Shinnecock, Moriches, and the Great South Bays.
How did the blue-spotted salamander end up in Montauk 100 miles east of its off-Long Island population in New Jersey? The ancient barrier island route may account for it reaching the very eastern tip of Long Island. The most active land bridge on eastern Long Island is Napeague. It’s only about 3,000 years old. Water used to pass freely between the Peconic Estuary and the Atlantic Ocean, where condominiums, restaurants, and single-family residences sit today. Napeague Bay once connected to the ocean, but was closed off on the south by re-entrant sand drifting from the east and an offshore bar moving onto land.
Lots of plants and non-flying animals reached Montauk by way of the Napeague isthmus. Perhaps the best example is the pitch pine, Pinus rigida. It came from the south with many other trees, shrubs, and wildflowers that followed the retreating glaciers northward. Long Island, most likely because of its separation from New York and New Jersey by the East and Hudson Rivers, was one of this procession’s last stops. Of the three most common conifers native to Long Island, the pitch pine is the most abundant and is the dominant tree in the Central Pine Barrens. The juniper, or eastern red cedar, is the next most common and the white pine ranks third, but on Long Island it is only abundant in East Hampton’s Northwest Woods.
The pitch pine and eastern red cedar have been slowly marching eastward on both the North and South Forks. Pitch pines are well established on Napeague, but not in Montauk, with the exception of the Walking Dunes area at the west edge of Hither Woods. The eastern red cedar has reached farther into Montauk but is nowhere near as common as white oaks, Canada shadbush, and hickories. The Japanese black pine, introduced into East Hampton’s and Amagansett’s dune lands shortly after World War II, has been moving easterly over the Napeague land bridge at a relatively fast clip and is about to conquer Montauk unless it is stopped. The population on the Montauk Downs golf course was planted there.
Chipmunks were not common in Montauk in the early 1900s and gray squirrels are still rather rare. But larger mammals — gray fox, red fox, skunk, deer, opossum, and raccoons — negotiated the Napeague isthmus early on. Today, except for a very rare sighting now and then, skunks and gray foxes are almost nonexistent in Montauk.
Woodchucks have been on Long Island, including the North Fork, for centuries, but only within the last 20 years have they been establishing on the South Fork. They have yet to reach Amagansett and Montauk, but it will happen. Southern flying squirrels are longstanding in central Long Island and the western part of the North Fork, but it’s only been in this century that they have been seen here and there on the South Fork as far east as Wainscott and Bull Path in Northwest. Some say that nuisance mammal trappers are responsible for these two rodents on the South Fork; it remains to be seen.
Tupelos have a southern Appalachian origin but have had no trouble reaching Montauk. It’s a different story, however, for tulip trees and walnuts. Though they are not uncommon in Noyac and deciduous forests to the west, you’d be hard pressed to find one in Montauk. On the other hand, American holly is well established in Montauk all the way into the Point Woods, but is very rare on Napeague, although not uncommon in Springs and western Amagansett. Holly berries are favorites of certain migratory birds such as robins, bluebirds, catbirds, and towhees. The same migratory birds that are responsible for bringing us southern ticks like the lone star tick, probably brought us holly berries hundreds of years ago.
Black cherries are everywhere and much of their distribution is attributed to birds eating the fruit and defecating the pits around. A close relative, the chokecherry, produces berries that are similarly eaten by birds, but for some reason are rare on Long Island. Maybe that’s because they ripen in late summer when the birds are beginning to go south and not north.
Local indigenous people preferred white oak acorns for making flour over acorns from black and scarlet oaks. Maybe birds shared a similar preference and that’s why Hither Woods is filled with them.
Southern plants and southern birds continue to make landfall on Long Island as the northern hemisphere warms up and the winters become milder. Flora and fauna are always coming and going. A biped mammalian species is the biggest user of the Napeague land bridge these days. Where would Montauk be today without it? And didn’t someone see a coyote or coy-wolf in Bridgehampton recently? There you are.
Larry Penny can be reached via email at [email protected].