Bill Crouch Introduction Drift Fence & Pitfall Arrays Calling Anuran Surveys Egg Mass Counts Preliminary Results

Scientists in the Field Introduction The perceived worldwide amphibian decline has caused great concern. However, there is very little published literature on long term amphibian population trends. The scarcity of published data, both on amphibian populations and the seasonal ponds on which many depend, has prompted us to begin this research. Concerns over worldwide amphibian declines surfaced in the late 1980's when scientists began to realize the extent of anthropogenic impacts on frogs and salamanders (i.e. acid rain, UVb, water pollution, pesticide runoff, habitat destruction). Many conservationists and biologists though, find that there is very little published literature on long term amphibian population trends which makes it difficult to determine the difference between a man-made decline or simply a natural population fluctuation. This lack of information on populations nationwide has prompted the formation of the North American Amphibian Monitoring Program or NAAMP. The goal of this organization is to develop a statiscally defensible monitoring protocol to survey amphibians. The scarcity of published data, both on amphibian populations and the seasonal ponds on which many depend, particulary in the northeast has prompted us to begin this research.

Our ongoing work at the University of Rhode Island at the Department of Natural Resources Science centers around the use of seasonal (vernal) pools by amphibians. We are working on two fronts to better understand how these systems work and how best to monitor the amphibian populations that depend on them. The first step is to describe the system, that is, we are attempting to model the seasonal movement chronologies of amphibians using these upland, seasonal ponds in southern Rhode Island. This work was started in Feburary 1997 and is continuing with data collection scheduled through November of this year. The second aspect is to test some current monitoring protocols put forth by the North American Amphibian Monitoring Program (NAAMP) and the Biological Resources Division of the USGS. The technique that will be tested is the Calling Anuran Survey (CAS). Many of you have probally heard of this program where volunteers listen at selected wetlands and record what species of frogs they hear. Initially our data collection was centered around the Wood Frog (Rana sylvatica) but we soon realized that we could collect data for other species of frogs and toads as well. To date we have monitored 13 of the 19 species of amphibians in Rhode Island and nearly all the species that use seasonal ponds as their primary breeding area. The anurans that are most often encountered are: Green Frogs (Rana clamitans); Wood Frogs (R. sylvatica); Spring Peepers (Pseudacris crucifer); Gray Treefrogs (Hyla versicolor) and American Toads (Bufo americanus). The salamanders that we most frequently see are: Red-backed Salamanders (Plethodon cinereus); Spotted Salamanders (Ambystoma maculatum); Marbled Salamanders (A. opacum); and Red-spotted Newts (Notophthalmus viridescens). Other species that are found less often are: Bullfrogs (R. catesbeiana); Pickerel Frogs (R. palustris); Four Toad Salamanders (Hemidactylium scutatum); and Northern Two-lined Salamanders (Eurycea bislineata). To gather the data we use the following three techniques: (1) Drift Fence and Pitfall Arrays; (2) Calling Anuran Surveys; and (3) Egg Mass Counts.

Marbled salamander. Bullfrog. Woodfrog. American toad. Redback salamander.