Under a National Park Service/Wildlife Conservation Society Cooperative Agreement, an inventory of amphibians and reptiles at Acadia National Park in Maine was conducted from March through September 2001. Seven standardized sampling methods were employed; anuran call counts, egg-mass counts, time-constrained search, coverboards, turtle trapping, minnow trapping, and drift fence arrays. In addition, animals encountered outside of standardized surveys (temporally or spatially) were recorded as incidental encounters. The method that documented the most species was incidental encounters, which recorded all 18 species found during this inventory. Nine species were recorded during wetland time-constrained search, eight with minnow trapping, seven during woodland/old field time-constrained search, six by anuran call counts, five species each using coverboard and stream surveys, four species using drift fencing and pitfall traps, three during egg-mass counts, and two species in the course of turtle trapping. All 18 species were documented in wetland habitats, followed by 17 on roads, 14 in uplands, nine in streams, and seven in tidal habitats.
Many species were observed crossing roads throughout the park during rainy weather or breeding/nesting seasons. In particular, spotted and four-toed salamanders, painted and snapping turtles were found crossing Route 233 near Eagle Lake and on Duck Brook Road in significant numbers. Road casualties may be a significant mortality factor for amphibians that breed in wetlands in close proximity to well-traveled roads and turtle and snake populations at these sites may be similarly impacted. Regular monitoring and temporary closure of these roads, during peak breeding and nesting seasons (especially on rainy nights) are recommended to prevent episodes of high road mortality of these species. Road sections where major amphibian and reptile mortality occur should be evaluated for elevating above grade or installation of wildlife friendly road tunnels and leaders to provide safe travel routes for migrating animals in heavy traffic areas.
Of the four species not found during this survey, grey treefrog and musk turtle were historically present but rarely encountered. They may still be present. More focused sampling is needed to determine their status. The absence of two formerly common amphibian species, northern leopard frog, and northern dusky salamander is more troubling. Their disappearance is not likely due to road mortality, and their apparent extirpation from the park may be due to any of a number of factors linked to recently documented amphibian declines. These include air pollutants in their many forms, pesticides, the impact of introduced fishes, and diseases such as iridovirus and chytrid fungus. Additional work focused on these two species including intensive surveys of historical sites and analysis of habitat condition and changes, including pollutant loads at those sites is recommended to determine the possible causes for the extirpation of these two species.
Each survey method was useful in sampling different habitats and specific species, and it is recommended that any future inventories targeting the entire herpetofauna include each method, and sample a wide range of habitats. Conversely, an inventory targeted at a particular species will need to sample specific habitats using only one or two methods. While a detailed plan for monitoring is beyond the scope of this inventory, the results suggest that, in terms of both feasibility and priority, a monitoring program based on anuran call counts, time or spatially constrained stream/brook surveys, coverboards, and aquatic turtle trapping would be the most useful methods for generating quantitative data useful for trends analysis.
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