Davis College of Agriculture, Natural Resources and Design
Division of Forestry and Natural Resources
Reliable species identification is vital for survey and monitoring programs. Recently, the development of digital technology for recording and analyzing vocalizations has assisted in acoustic surveying for cryptic, rare, or elusive species. However, the quan- titative tools that exist for species differentiation are still being refined. Using vocali- zations recorded in the course of ecological studies of a King Rail (Rallus elegans) and a Clapper Rail (Rallus crepitans) population, we assessed the accuracy and effective- ness of three parametric (logistic regression, discriminant function analysis, quadratic discriminant function analysis) and six nonparametric (support vector machine, CART, Random Forest, k-nearest neighbor, weighted k-nearest neighbor, and neural net- works) statistical classification methods for differentiating these species by their kek mating call. We identified 480 kek notes of each species and quantitatively character- ized them with five standardized acoustic parameters. Overall, nonparametric clas- sification methods outperformed parametric classification methods for species differentiation (nonparametric tools were between 57% and 81% accurate, paramet- ric tools were between 57% and 60% accurate). Of the nine classification methods, Random Forest was the most accurate and precise, resulting in 81.1% correct classi- fication of kek notes to species. This suggests that the mating calls of these sister species are likely difficult for human observers to tell apart. However, it also implies that appropriate statistical tools may allow reasonable species-level classification ac- curacy of recorded calls and provide an alternative to species classification where other capture- or genotype-based survey techniques are not possible.
Digital Commons Citation
Stiffler, Lydia L.; Schroeder, Katie M.; Anderson, James T.; McRae, Susan B.; and Katzner, Todd E., "Quantitative acoustic differentiation of cryptic species illustrated with King and Clapper rails" (2018). Faculty & Staff Scholarship. 1283.
Stiffler LL, Schroeder KM, Anderson JT, McRae SB, Katzner TE. Quantitative acoustic differentiation of cryptic species illustrated with King and Clapper rails. Ecol Evol. 2018;8:12821–12831. https://doi. org/10.1002/ece3.4711