Hoppe, D.M. and R.G. McKinnell. 1991. Distribution and prevalence of the Kandiyohi frog in Minnesota. Final report submitted to the Minnesota Department of Natural Resources. 4+ pp.
Leopard frogs were captured and released at 20 different sites in 10 Minnesota counties, including 8 counties where the kandiyohi morph had been previously reported and 2 other counties within the general range of this mutant frog. Surveys of 8 sites in 4 counties where frogs had been previously abundant revealed no frogs in 1990. A total of 2008 frogs were capture and examined, among them being 8 kandiyohi frogs from 4 different counties (freq. = 0.4%) and 129 burnsi frogs (freq. = 6.4%). These data include 3 new county records for these leopard frog mutations.
The overall incidence of kandiyohi frogs found in these surveys compares favorably with 0.6% kandiyohi reported in 1965, but much larger sample sizes and more county surveys are needed to assess changes in the range or prevalence of this mutation. The burnsi morph appears to be relatively unaltered in distribution or abundance in the limited counties surveyed within the burnsi range. Collections are still needed in 8 Minnesota counties within the previously-known range of the kandiyohi morph, at least 2 Minnesota counties of interest outside the known range, and several South Dakota counties, in order to complete an update of distribution and abundance of the kandiyohi leopard frog.
Leopard frogs in general appear to have been "regionally abundant" in 1990-91, but were absent or at decreased levels in some sites where they were abundant in the late 1970's.
The results of this study, along with some of the investigators' previous research and a general discussion of leopard frogs in Minnesota were published in the Nov-Dec, 1991, issue of The Minnesota Volunteer.