Saugus Iron Works National Historic Site Amphibian and Reptile Inventory: March – September 2001

Cook, Robert; Brotherton, David; Behler, John

Under a National Park Service /Wildlife Conservation Society Cooperative Agreement, an inventory of amphibians and reptiles at Saugus Iron Works National Historic Site (SAIR) was conducted one day per month from April through September 2001. Five standard methods were employed: anuran calling surveys, time-constrained searches, coverboard surveys, turtle trap surveys, and minnow trap surveys. In addition, animals encountered outside of standardized surveys (temporally or spatially) were recorded as incidental encounters. The four amphibian and reptile species documented in 2001, plus one observed in 2000, represent 50% (5/10) of the species already known or believed to be potentially occurring at SAIR. Species recorded were northern green frog, northern two-lined salamander, northern brown snake, and common garter snake, plus common snapping turtle in 2000. The diversity of herpetofauna at SAIR is limited by its small size, history of disturbance, limited habitats, and urban location. There are no ponds present and the Saugus River is well drained, with little standing water at low tide. Amphibians and reptiles at SAIR are largely limited to species that do not breed in ponds, have small home ranges and are capable of maintaining a population in a small habitat patch, or are mobile species that disperse along the river or across the adjacent uplands. For these latter, successful movement to SAIR across the adjacent landscape or along the Saugus River is challenging due to urban development and culverts. Of the species found in SAIR, northern two-lined salamander is the most habitat specific. All life stages (eggs, larvae, and adult) are spent in stream habitat. In spite of the park’s history of disturbance and presence in an urban landscape, northern two-lined salamanders are abundant at SAIR, primarily in the small stream/seep east of the maintenance building. The remaining species – northern brown snake, common garter snake, northern green frog, and common snapping turtle – are urban-tolerant generalists. Both brown and garter snakes can persist in small habitat patches such as SAIR, whereas northern green frogs and common snapping turtles likely utilize SAIR as part of larger home ranges. The Slag Heap and uplands of the Historic/Administrative survey area provide an important and rare habitat feature in an urban area: turtle nesting habitat adjacent to the river. This spares females a risky nesting foray across roads, which is a major source of mortality. The Historic/Administrative area’s long history of use for turtle nesting suggests that female turtles using this stretch of river return to use it repeatedly.The herpetofauna of SAIR are subjected to numerous stressors, including global ones such as acid precipitation and mercury deposition; regional ones such as water pollution, streamflow alterations, and road kill; and local ones such as invasive alien plants and animals. However, the impacts of regional and local stressors may be lessening, and staff at SAIR should continue their efforts to improve the site’s environmental quality. Although it is unlikely that SAIR will ever support an extensive herpetofauna, it is an important part of a larger system of protected “greenspace” along the Saugus River, and provides regionally important habitat. It is likely that, over time, additional species will be recorded at SAIR, particularly as environmental conditions improve. A monitoring program which uses coverboard surveys, searches of the marshes and stream, surveys of the Saugus River with minnow traps and turtle traps, and general time-constrained searches is recommended.

Saugus Iron Works National Historic Site Amphibian and Reptile Inventory: March – September 2001

Series

Collections