Traditional monitoring

Seventeen ponds were visited in June as a part of SKB’s regular monitoring program that has been running since 2012³⁵. In short, ponds were visited twice during the mating period and for one hour at each occasion. All calling males and silent observed individuals were counted. The activity of P. lessonae during the spawning period is highly dependent on the water temperature. Reproduction does not start before the water has reached a temperature of at least 16 °C²¹, and 19 °C is needed for a successful completion of the larval cycle³⁶. In addition to the regular program, six ponds were visited to estimate presence of spawn in July, and fourteen ponds were visited at the end of the summer to count small and adult frogs. In May 2016, SKB launched a six weeks intensive monitoring study of ponds with known occurrences of P. lessonae³⁷. In that study each pond was visited daily, and calling and sighted individuals following the same procedures as in the regular monitoring program.