Napatree Point Migration is for the Birds … Bats and Butterflies
March 27, 2023
WESTERLY, R.I. — Coastal barrier beaches in southern New England provide critical habitat for migrating bird species, and one of their favorite stopovers is an 86-acre peninsula that extends 1.3 miles into Little Narragansett Bay.
The Napatree Point Conservation Area has been designated a “globally important bird area” by the National Audubon Society, it is listed as a Climate Response Demonstration Site by the University of Rhode Island’s Coastal Institute, and is part of the U.S. Fish & Wildlife Service’s Coastal Barrier Resources System. The Watch Hill barrier beach supports many species of federally and state-listed endangered birds, including American oystercatchers, least terns, ospreys, piping plovers, and roseate terns.
During the last few days of June 2020, hundreds of additional birders trekked to the southwestern-most point in the Ocean State to catch a glimpse of a Terek sandpiper. It was the first, and still only, documented sighting of the species in Rhode Island and is considered by some to be the rarest bird to show up here in decades.
Terek sandpipers breed in Finland and across much of northern Russia and winter on the coast of East Africa, Australia, and South Asia. It is named for the Terek River, which flows into the Caspian Sea, where it was first observed.
The skinny Watch Hill peninsula, however, is an attraction for more than just birds and people, 40,000 of which visited the conservation area last year. It’s also an oasis for bats and butterflies.
A talk titled “Napatree Point Migrations: Birds, Bats, and Butterflies” was held March 24 at the United Theatre on Canal Street. The hour-long discussion was sponsored by The Watch Hill Conservancy and the Coastal Institute and featured three speakers — professor Peter Paton, chair of the University of Rhode Island’s Department of Natural Resources Science; Peter August, professor emeritus in URI’s Department of Natural Resources Science; and David Gregg, executive director of the Rhode Island Natural History Survey.
Paton, whose research focuses on the conservation of vertebrate populations, with an emphasis on coastal birds, said Napatree Point “is an International destination for birds.”
He noted 970 bird species can be found in the continental United States. Of those, 434 have been detected in Rhode Island and 259 at Napatree Point.
The vast majority, about 90%, are migrants, according to Paton. The bird species observed at Napatree Point include raptors such as hawks, falcons, eagles, and owls. At least 23 species of warblers, such as the blackpoll warbler, have been recorded at Napatree, most of which, Paton said, use the peninsula briefly before heading to their exotic winter destinations in the Caribbean or South America.
While August noted “Napatree is not super great bat habitat,” the sandy area is a popular spot for six bat species that occur in Rhode Island. The six species of winged mammals who seek food and shelter at the southern tip of Rhode Island are equally divided into two classes: tree bats (red bat, hoary bat, and silver-haired bat) and hibernators (big brown bat, little brown bat, and tricolored bat), according to August, who is the president of The Watch Hill Conservancy.
Bats appear at Napatree in the spring and early summer but in low numbers. Activity increases in late summer and fall.
Of the nearly 19,000 bats recorded over four years of sampling at Napatree Point, about 60% have been big brown bats, followed by silver-haired bats, red bats, and hoary bats. It’s not uncommon in August or early September to have more than 500 bat passes recorded in a single night, said August, who began his career in ecology studying bats in Venezuela in the late 1970s. He also noted a single big brown bat can dine on some 2,000 mosquitoes in one night.
Little brown bats and tricolored bats have been recorded less often.
New England populations of little brown bats, historically the region’s most common species, have been decimated by white-nose syndrome, a fungus that spreads rapidly through colonies of hibernating bats in caves and mines. Big brown bats hibernate in smaller colonies, frequently in attics and walls of buildings, and are not as prone to fungal infection, according to August.
Tricolored bats are currently being considered for listing under the Endangered Species Act.
Tree bats got that label because they tend to roost in trees over the summer. By late fall at the latest, they are making their way to the southeastern United States to winter.
Gregg, a senior fellow at the Coastal Institute, said a number of insects, including dragonflies and butterflies, migrate to access food and breeding sites during the northern winter, and a number of these insects can be seen on Napatree Point storing up energy for the journey ahead.
He noted monarch butterflies are the best-known example. Butterflies born here of northward-flying parents make the southward migration in the fall. He said recent research shows most Mexico-wintering butterflies come from the central United States. Monarchs that mature along the East Coast, including those from New England that congregate on Napatree Point in cedar trees, make up only a small percentage. Napatree’s goldenrod and saltbush are valuable nectar sources for south-bound monarchs, according to Gregg.
His presentation included this nugget: An individual monarch, which weighs about half a gram, can travel some 2,000 miles. For comparison, it would take about 100,000 monarchs to equal the weight of an average person and that person would need to travel 200 million miles to equal the butterfly’s journey.
Napatree Point is owned, managed, and protected by the Watch Hill Fire District, the Watch Hill Conservancy, the town of Westerly, the state, and private landowners. Conservation easements protect it from future development.