Airport Clears Habitat Land

Mitigation Plan Saves Rare Plants Alongside Purple Tiger Beetles; Sandy Pathways Are Created Across West Tisbury Road

By James Kinsella
Gazette Senior Writer

Consider the outlook of a purple tiger beetle living at the Martha's Vineyard Airport.

For the beetle, life has been good. The climate is agreeable. Its ancestors have made their home there for generations. Best of all, there's been a nice sandy path where the beetle, a carnivorous sort, can more easily spot its meals moving along.

But trouble has surfaced for the beetle. Humans are building an airplane ramp and taxiway near the start of runway 24 at a cost of $4.3 million. So much for the sandy path.

The beetle, however, need not despair. It turns out the humans have created a whole network of sandy paths south of the West Tisbury Road, just for the purple tiger beetles. The beetles, which fly in the spring and fall, can fly across the road to the new paths.

Those sandy paths are just one of a number of specific environmental steps taken at the airport to preserve habitat for rare species.

State environmental officials require the steps as a necessary legal prelude to construction work and other clearing at the airport.

The process is known as mitigation: creating new habitat and transplanting rare species as necessary to compensate for the destruction of habitat that is home to those species.

Additional steps at the airport include creating conditions near the sandy paths that will favor young scrub oaks, which are a favorite food for the barrens buckmoth, and creation of a grasslands habitat near the start of runway 6, which will provide a home for the grasshopper sparrow, purple needle-grass, sandplain blue-eyed grass and grass-leaved ladies'-tresses.

The grasslands are being created in the area on the north side of the Edgartown-West Tisbury Road, where five acres of dead pines have been cut in recent weeks. The rare grasses found in the taxiway and ramp construction area have been replanted in the new grasslands.

Acting airport manager Sean Flynn said that although the cutting was not needed for safety reasons, the work will add to the safety of the approach.

The same goes for the taller trees just across Edgartown-West Tisbury Road, where the beetle pathways have been created.

The mitigation strategy there will foster young scrub oaks by removing the overstory of larger trees. The barrens buckmoth seeks out the tender shoots of the smaller scrub oaks to eat.

"This is first and foremost an airport," acting airport manager Sean Flynn said of the work, slated for completion either late this year or early next spring.

Current demand rather than future need is spurring the project now underway, Mr. Flynn said. The airport needs ramp space for airplanes temporarily visiting the airport. The upgrade also requires the airport to conform to federal rules by moving the taxiway farther from runway 6-24.

The runway, which runs southwest to northeast, is named for the corresponding points of the compass. Airplanes landing or taking off into a northeast wind would head 6 points east of due north. Hence an airplane taking off into a northeast wind would start at the runway's southwestern end, with the strip known in this case as runway 6. An airplane landing in a southwestern wind would be heading 24 points along the compass; hence the strip is known as runway 24.

Ninety-five per cent of the project will be funded by the federal government, with the remaining cost split between the airport and the state. No specific cost was available for the mitigation work undertaken by the airport.

Before beginning construction, the airport was required under the state Endangered Species Act to obtain a conservation and management permit from the Massachusetts Division of Fisheries & Wildlife. The permit will cover 14 projects proposed in the airport master plan for construction over the next eight years.

Some 17.4 acres of state-listed rare species grassland, scrub oak, and what are termed early successional pathway habitats will be affected by the project, although according to the project summary, the end result will be a cumulative net gain of 36.6 acres of rare species grassland, scrub oak and early successional pathway habitats.

The permit lists nine general and 16 special conditions, including the retention of a qualified botanist to conduct surveys on the property, and the documentation of all exotic plant species on the property.

Mr. Flynn said the mitigation will involve continuing work on the part of the airport. For example, the airport periodically will mow sections of scrub oak south of the Edgartown-West Tisbury Road to encourage the growth of new scrub oak, food for the barrens buckmoth.

Baystate Environmental Consultants of East Longmeadow is working with the airport on the mitigation efforts. Baystate environmental scientist Erin Gillen was on the Vineyard this week to conduct surveys of rare species.

Ms. Gillen said that not only are transplanted rare grasses taking root in their new habitat at the other end of runway 6-24, but new growth has been spotted as well.

At the moment, the fate of affected insects is harder to tell. The barrens buckmoth is underground at this time of year, while the purple tiger beetle is not easily spotted in general.

As for the grasshopper sparrow, a bird sometimes born on the Vineyard, Mr. Flynn said none have been spotted this year. He speculated that spring storms might have discouraged their arrival this year.

To be on the safe side, the airport held off construction until the time when any grasshopper sparrows would have fledged. The birds live most of their lives south of the Vineyard.

Is mitigation worthwhile? Ms. Gillen said yes. By deliberately frustrating habitat succession - stopping a Vineyard grassland from becoming a Vineyard oak forest - she said the airport is ensuring that these rare plant and animal species will continue to have a place to develop and live.

Mr. Flynn said the airport is not running a nature center. "Sometimes it feels like it is, but that's all right with us," he said, adding: "We try to be good neighbors to the plants and animals here."