2012 Volume 80 Issue 2 Pages 207-213
The countermeasures that enable frogs to cross agricultural canals have been developing because frogs often drown in agricultural canals with vertical concrete walls in Japan. The objective of this study was to develop a method for evaluating the population viability of the Japanese Brown Frog Rana japonica after countermeasures are installed. Two types of simulation models were examined; a ‘basic model’ based on the age-structured model and a ‘crossing model’ to consider the proportion of frogs crossing canals.
Parameter values such as survival rate and fecundity were estimated from observation data of age-dependent population fluctuations. Comparison of a basic model simulation with the observation data suggests model validation. The crossing model simulation with an initial population of 1,000 showed that a crossing proportion of 100% would achieve a 95% population viability after 40 years, suggesting frog migration should be ensured in this case.