A Comparison in Colorado of Three Methods to Monitor Breeding Amphibians

We surveyed amphibians at 4 montane and 2 plains lentic sites in northern Col- orado using 3 techniques: standardized call surveys, automated recording devices (frog-log- gers), and intensive surveys including capture-recapture techniques. Amphibians were ob- served at 5 sites. Species richness varied from 0 to 4 species at each site. Richness scores, the sums of species richness among sites, were similar among methods: 8 for call surveys, 10 for frog-loggers, and 11 for intensive surveys (9 if the non-vocal salamander Ambystoma tigrinum is excluded). The frog-logger at 1 site recorded Spea bombifrons which was not active during the times when call and intensive surveys were conducted. Relative abundance scores from call surveys failed to reflect a relatively large population of Bufo woodhousii at 1 site and only weakly differentiated among different-sized populations of Pseudacris maculata at 3 other sites. For ex- tensive applications, call surveys have the lowest costs and fewest requirements for highly trained personnel. However, for a variety of reasons, call surveys cannot be used with equal effectiveness in all parts of North America.