by Joe Mish
The mature boulder strewn woods of the Sourland mountain ridge had served as a refuge to the patriots of the American Revolution during times of British occupation. Today this unique environment attracts a concentrated population of eastern box turtles.
The Sourland ridge has a unique geology that stands in stark contrast to the gently rolling hills of New Brunswick shale which flank it. The ridge runs east-west from Hillsborough township in Somerset County, across northern Mercer and southern Hunterdon counties to the edge of the Delaware River at Lambertville. Rising abruptly from the rolling landscape, the ridge has attained the status of, ‘mountain’.
These lightly trampled woods are a magnet to box turtles and the dozen or so empty carapaces found over several years are evidence of a long term favorable habitat. Exactly why there appears to be such a concentration of turtles within an area of less than a half square mile is a tantalizing mystery. Outside of the Sourland ridge, locally, I have not crossed paths with another box turtle but surely they must be around as the eastern box turtle is found throughout the state.
Box turtles are strictly terrestrial and most commonly found in moist woods. While the watery environs of this most densely populated state tend to remain relatively stable, it is the land that bears the brunt of New Jersey’s burgeoning human population. So it is that the box turtle needs some public relations effort to raise awareness in the face of chronic destruction of finite habitat. The box turtle is not currently listed as threatened or endangered by NJ state and Federal Agencies, but its status bears watching.
Large and numerous boulders of dense rock and a scarce water supply have kept new homes and farming at bay in the Sourlands. Timber has been harvested since colonial times and continues today. This practice along with the natural attrition of fallen timber allow moments of diversity to exist. The succession of plants growing in the now open sections of forest canopy increase the variety of bird and animal species by providing ideal habitat not found in a less diverse mature forest. As the forest evolves the ideal habitat for a given species disappears. The unbroken tract of the Sourland Mountain ridge is important because it allows an unhindered local migration to other areas of ideal habitat.
The area today is characterized by large mature trees, mostly yellow poplar and ash along with scattered oaks and hickories. Hard and soft maples are interspersed with ironwood, black birch and yellow birch in the moist areas along mostly seasonal streams. Massive American beech trees sit in the midst of radiating groves of younger sucker growth. The under story is filled with dogwood, sassafras and a variety of viburnums. Blackberries, dewberries, poison ivy and wild grapes flourish where edge has been created. Yellow violets, cardinal flower and wild azaleas are also common. Patches of trillium and mushrooms grow among the damp forest floor and decaying timber.
Scattered seeps of water spring from the ridge, ultimately flowing to the Millstone or South Branch watersheds and to the Delaware River in the west. Uncommon boggy areas form where the land flattens along these watercourses. Sufficient moisture collects to support an August bloom of cardinal flowers. Random openings in the forest canopy allow the growth of blackberries and dewberries along with a host of berry producing shrubs and other edge species. It is in such a transitional zone where the box turtles and their artifacts have been observed.
Numerous turtle encounters during the summer and early fall have added a richness to my woods travel. Interacting with so many turtles gives a good impression of their personalities. Perhaps the concept of personality in a turtle seems a bit odd but the differences were apparent in terms of shyness. Box turtles are the only native New Jersey turtle with a hinged lower shell or plastron. When frightened they are able to pull their head, legs and tail completely into their upper shell or carapace, and seal the opening by raising the plastron tight to the carapace.
The turtle in the accompanying photo was unique in that he was not intimidated. His exposed posture gave the impression of an alpha animal defending his territory. The magic was complete when an errant breeze allowed a transient shaft of sunlight to penetrate the dark under story and highlight a brilliant red eye. The image was stunning. It revealed nobility not associated with a common box turtle. This guy would make a perfect ‘poster child’ for any environmental awareness program or even a mascot for a high school football team.
While isolated pockets of habitat may contain elements attractive to many animal species, the loss of continuous tracts of undeveloped land prevents natural migration as local habitat evolves or is lost. Left with wooded islands of diminished diversity the adrift survivors from these isolated pockets of favorable habitat may indeed land on shores hostile to their survival. The importance of greenways and stream corridors cannot be underestimated and must be considered when areas are lost to new construction.
