Finding Idaho’s giant stream salamander with modern maps
An Idaho giant salamander rests on a rock in mid-stream and a modeled range map colored by habitat suitability that was developed from survey locations where the species was observed.
Land management activities may be limited by the presence of sensitive aquatic species in nearby streams, but large uncertainties often exist about whether these species are actually present at specific sites. One example involves the Idaho giant salamander, which is recognized as the official state amphibian, but until recently has lacked accurate habitat and distribution information.
To address this challenge, scientists from the Rocky Mountain Research Station aggregated data on the locations of Idaho giant salamanders from historical sources like museums and state or federal resource management agencies, along with new data from citizen science eDNA databases like the eDNAtlas. This allowed the scientists to compile more than 700 locations that documented the presence or absence of Idaho giant salamanders. This dataset was combined with specialized modeling techniques developed for stream networks which allowed the team to understand the type of habitat these salamanders preferred and to accurately map their distribution across multiple river basins and National Forests.
The scientists found that Idaho giant salamanders prefer cool, heavily shaded streams that are much steeper than most fish species prefer. The results also indicated that the salamander’s range currently encompasses 13,000 kilometers of stream with core habitats centralized in about half this area at lower elevations in major river basins.
To make these results useable for land managers in planning activities, the range maps are available as a Geographic Information System (GIS) data layer which accompanies the study describing this research. This approach to developing accurate distribution information is applicable to many other species, especially now that large eDNA databases are available and contain recent survey data on a broad spectrum of aquatic species.