What hasn't yet been demonstrated for any species is the existence of a relationship between captures and total population size. Also, no group has ever used within and among year variances in trap captures to estimate the number of traps that must be set and water bodies sampled to achieve a given level of sampling precision. Trap type needs further investigation. Net bags of leaves are placed in streams and ponds where they are colonized by salamander larvae. These bags can then be placed in buckets and the larvae separated out.
Bags have the several advantages.
They are relatively immune to observer bias, sample sizes are easy to accumulate, and site disturbance is low. Further evaluation is needed to determine the species and conditions for which it works best. Because current larval sampling schemes focus on single species or specialized habitats, it will not be appropriate to develop a larval monitoring program without a great deal of additional methodological research. We propose the development of pilot monitoring programs for aquatic amphibians in several parts of the country to explore issues of sampling variance and, in some cases, validate the relationship between capture rates and total population size. Using National Wetland Inventory Maps, or other means of determining potential aquatic amphibian habitat, candidate streams and ponds are identified and sampling locations chosen either randomly or via a stratified approach to more efficiently capture estimates of change for uncommon species.