Block Island National Wildlife Refuge
Northeast Region
 

Wildlife & Habitat

The following was excerpted from the plan (CCP) for Block Island National Wildlife Refuge. For more information download a copy (1.32 MB) of the Block Island National Wildlife Refuge Comprehensive Conservation Plan.

Physical Resources: Topography, Soils and Hydrology

Glaciers deposited approximately 60 feet of New Shoreham drift, forming the island’s hilly, morainal topography. Up to 3 feet of wind-deposited silt loess overlies glacial till deposits. Parts of Sandy Point were formed by finely sorted alluvial sands and wave and tidal shifting and deposition.

Terrain on the northern parcel, around the North Light lighthouse, is rolling dunes and swales averaging 5- to 10-percent slopes; soils are primarily sand. Beane Point is a 21-acre upland with less than 5-percent slopes composed of Paxton, very stony-fine sandy loams. The 13-acre Nevuus- Greenburg tract and O’Toole tract are primarily upland with less than 10-percent slopes also composed of Paxton, very stony-fine sandy loams.

Block Island’s groundwater supply depends entirely on rainfall, with kettle ponds and wetlands perched on compacted, clay soils. The Nevuus-Greenberg tract contains two very small ponds; otherwise, no freshwater lakes or ponds lie on refuge property. Adjacent to refuge lands, however, are several small freshwater ponds, and the brackish Sachem Pond and saline Great Salt Pond. More than 365 ponds and emergent wetlands on the island provide a critical resource for many species.

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Biological Resources:

Block Island is unique from many perspectives, not least of which are its biological resources. In 1991, The Nature Conservancy selected Block Island as one of its 12 initial “Last Great Places” in the western hemisphere, primarily due to its ecological significance. Our report, “Northeast Coastal Areas Study”(1991) noted the unique natural resources on Block Island:
“…one of the most important migratory bird habitats on the East Coast… [as it]…provides a critical link or stepping stone in the migration of many birds, particularly raptors and passerines, between southern New England and eastern Long Island, and points north and south.”

The Nature Conservancy considers Block Island an internationally significant biodiversity reserve due to the presence of rare and endemic species and habitats, and because of the concentrations and diversity of songbirds, shorebirds, and raptors that migrate through the area. At least 15 rare, threatened, or endangered federal or state listed species, including birds, insects, mammals, and plants, reproduce on the island. Many additional rare birds pass through the island during migration.

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Vegetation

Block Island Refuge is primarily upland, except for beach habitat at Cow Cove, Sandy Point, West Beach, and Beane Point. Beach habitat includes bare sand, beach grass (Ammophila brevigulata), poison ivy (Rhus radicans), bayberry (Myrica pennsylvanica), wild rose (Rosa rugosa), and beach plum (Prunus maritima). Upland shrub habitat includes northern arrowwood (Viburnum recognitum), pokeweed (Phytolacca americana), Virginia creeper (Parthenocissus quinquefolia), and bayberry.

Japanese black pine (Pinus thunbergii) has been planted extensively along eastern seashores since the 1940’s because of its remarkable ability to withstand salt spray. But the future of the black pines on Block Island is uncertain. A mixture of bayberry and non-native Japanese black pine with a poison ivy understory dominates Beane Point. Those black pines provide important nesting habitat for a colony of wading birds, namely, black-crowned and yellow-crowned night-herons. Approximately 25 percent of the black pine on Beane Point has already been lost to an infestation of the black turpentine beetle (Dendroctonus terebrans).

Native pitch pine (Pinus rigida) is also susceptible to black turpentine beetles and thus, is not a good replacement tree. Correspondence with Cornell University Cooperative Extension and Cape Cod Cooperative Extension suggest that chemical control of black turpentine beetle is not an option because of the proximity to water. At present, no native tree species resistant to the black turpentine beetle and tolerant of saline, shoreline environmental conditions is known.

Both the Nevuus-Greenberg and O’Toole tracts are characterized as shrub vegetation dominated by bayberry, arrowwood, winterberry, and chokecherry. The O’Toole property has a higher proportion of dry upland shrub.

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Threatened and Endangered Species

Two federally listed species are known to breed on Block Island: the American burying beetle (endangered) and piping plover (threatened). The Service has completed recovery plans for both species.

Block Island harbors one of only a handful of American burying beetle populations, and the only natural population known east of the Mississippi River. This beetle is the largest of the North American carrion beetles, whose numbers have so drastically declined that they were federally-listed as endangered in 1989. Surveys in recent years found the majority of the Block Island burying beetle breeding population in the grassland habitat on the southern end of the island. However, beetles have twice been documented on or adjacent to refuge land, including near Beane Point and just north of Great Salt Pond.

Beetles on the refuge are likely foraging primarily on dead pheasant chicks, and occasionally on dead gull and black-crowned night-heron chicks. Carrion availability may be the single greatest factor determining where the species can survive. Annual surveys and monitoring of the breeding population have concentrated on the southern portion of the island. Its northern portion, including the refuge, have not been surveyed as intensively.

For more information on the piping plover, including current numbers of nesting pairs and their productivity, click on the Plover Program link in the Quick Links menu above. On Block Island, most of the suitable beach habitat for plover lies between Settlers Rock and the Sandy Point Tip. Other than a small stretch of refuge beach, most is owned by the Town of New Shoreham. Under a cooperative management strategy with the Town, areas of the beach between the North Light and Sandy Point will be symbolically fenced if piping plover are seen exhibiting courtship behavior. We will erect nest exclosures around any suspected nest sites. The staff of The Nature Conservancy-Block Island help monitor this beach during the breeding season.

A group of two to four immature bald eagles has been observed near ponds through the past five summers (1997-2002), feeding on waterfowl and fish; one roost site near Middle Pond’s west shore has been documented. More monitoring is needed to document habitat use by these birds.

Some State-listed species also occur on the refuge. Thirty-seven black-crowned night-heron (Nycticorax nycticorax) (endangered RI) nests were documented in a colony on Beane Point in 1998, an increase from the 29 nests counted in 1996 and 1997. This population has been documented on Block Island since 1976; however, they did not move to the Beane Point location until 1985. Prior to this, the rookery was located on the south side of West Beach road and briefly on the south shore of Sachem Pond. In both of these settings, the rookery was in shrub habitat (Ferren and Myer 1998, Raithel pers com 2000). Nesting with the black-crowned night-herons are one pair of great egrets (Casmerodius albus) and one pair of snowy egrets (Egretta thula) (endangered RI). A few yellow-crowned night-herons (Nycticorax violacea) (endangered RI) nest nearby. This is the only heron colony known on the island. As stated earlier, these birds are nesting in a dying stand of Japanese black pine. Adjacent landowners have informed us that, before nesting in the black pine, the black-crowned night-herons used to nest in shadbush on the island. This has implications for evaluating how to replace the nesting structure provided by the black pine.

Three to five American oystercatchers (Haematopus palliatus) (endangered RI) also nest on Beane Point and occasionally have been found near Sandy Point. Sea beach knotweed (Polygonum glaucum) (endangered RI) is sometimes found near Sandy Point.

Block Island is the only place in Rhode Island where northern harriers (Circus cyaneus) (endangered RI) nest. A total of 15 nests occur on the island; up to six nests occur near refuge lands, but none have been documented on the refuge. Block Island is also one of only two places in the world where barn owls (Tyto alba – endangered, RI) nest in sea cliff cavities rather than in human-made structures or inland cliff crevices; however, none of the four known cliff sites are on refuge lands. No other nests are known for barn owls in Rhode Island.

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Birds

The Nature Conservancy has two permanent banding stations on Clayhead Preserve on the northern end of the island. More than 6,000 birds representing 95 species are banded in a given year. This banding provides valuable information on the diversity of species breeding and migrating on the northern tip of the island. The habitat consists of shrub-scrub pine and kettle ponds. Block Island is internationally famous among birders for its spectacular fall songbird migration. Data reveals that the island provides crucial habitat for both spring and fall migratory shorebirds and songbirds. Its northern tip, in particular, consistently supports large concentrations of fall migrants. Thousands of Neotropical migrants, representing 70 species, have been documented. Of interest is the fact that the vast majority of these fall migrants are juveniles. Studies indicate that juvenile birds are severely dehydrated by the time they reach Block Island, and that its approximately 365 small ponds and abundance of fruit-bearing shrubs provide life-saving rehydration. Many typically omnivorous migrants forage exclusively on berries while on Block Island. Northern arrowwood, northern bayberry, and pokeweed were the predominate fruit-bearing shrubs used by birds. Shrub habitat also provides resting shelter for migrating birds. Shorebirds pass through in large numbers during midsummer and early fall. Typically, 40 different shorebird species have been observed using the mudflats and saltmarshes and wrack lines on open beach, including piping plover and whimbrel.

The refuge gull colony, the largest in the State, has been surveyed since 1981. Rhode Island DEM, Refuge staff and The Nature Conservancy on Block Island have been monitoring the colony because of a concern the gulls could impact other native species through increased predation or physical displacement as they dominate nesting sites. Gulls are known to prey on piping plover chicks, and thus pose a threat to management for that species. The overall gull populations have been gradually decreasing. Closing the landfill on West Beach and switching to a transfer station in 1990 probably contributed to this decline.

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Mammals

Block Island is unique regarding mammals because no native, terrestrial mammalian predators reportedly occur on the island. Feral cats and Norway rats are the biggest threat to small mammals, bird eggs, and chicks. No predator control measures have been implemented on the refuge.

Seals occasionally haul out on the refuge shoreline near Sandy Point; however, no formal surveys have been conducted. The Block Island meadow vole (Microtus pennsylvanicus provectus) is considered endemic to Block Island. Other small mammals include the whitefooted mouse (Peromyscus leucopus), introduced muskrat (Ondatra zibethicus), house mouse (Mus musculus), and Norway rat (Rattus norvegicus). Since no surveys of bats have been conducted, we do not know what species, if any, use the refuge.

The overabundant population of white-tailed deer has been an important issue in recent years because deer are not native to the island, and there are no natural predators to control the population. The Town of New Shoreham and RI DEM administer a hunt program to reduce the deer herd on portions of the island. Huntable acreage is limited on the island, due to limited access on private and public lands.

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Invertebrates

Among many other species of invertebrates that occur here, the critically endangered American Burying Beetle (Nicrophorus americanus) breeds on the refuge. For more information please click on the link to the Threatened and Endangered Species section on this page.

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Amphibians and Reptiles

Green frog (Rana clamitans), peepers (Psuedacris crucifer), and red-spotted newts (Notophthalumus v. viridescens) occur in the island’s scattered freshwater ponds. Reptiles include common snapping turtle (Chelydra s. serpentina), spotted turtle (Clemmys guttata), eastern painted turtle (Chrysemys p. picta), northern water snake (Nerodia sipedon), eastern garter snake (Thamnophis s. sirtalis), northern brown snake (Storeria d. dekayi), and an occasional diamondback terrapin (Malaclemys terrapin). There is speculation that some of these may be distinct subspecies, since they have been separated from mainland populations for at least 8,000 years.

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Last updated: January 10, 2012