Acoustic amphibian monitoring, 2019 data summary: Mississippi National River and Recreation Area

Amphibians are a Vital Sign indicator for monitoring long-term ecosystem health in seven national park units that comprise the Great Lakes Network. We present here the results for 2019 amphibian monitoring at Mississippi National River and Recreation Area (MISS). Appendices contain tabular summaries for six years of cumulative results. The National Park Service Great Lakes Inventory and Monitoring Network established 10 permanent acoustic amphibian monitoring sites at MISS in 2015. Acoustic samples are collected by placing automated recorders with omnidirectional stereo microphones at each of the 10 sampling sites. Temperature loggers co-located with the recorders also collect air temperature during the sampling period. Eight of the nine species of frog and toad known to occur at MISS were found in 2019. The most well distributed species were Eastern American Toad, Gray Treefrog, Green Frog, and Northern Leopard Frog. Rarer are Blanchard’s Cricket Frog, Cope’s Gray Treefrog, Wood Frog, and Boreal Chorus Frog. American Bullfrog has not yet been detected on GLKN monitored sites but has been recently confirmed nearby (Pigs Eye Lake). Two of the ten sites—MISS02, MISS04—were not sampled in 2019 due to flooding, and occupancy of early calling species at MISS06 was determined inconclusive due to a late sampling start. MISS07 was also deployed late and results may contain some false absences due to late sampling. We expanded analyses and reporting in 2018 to address calling phenology and to provide a second metric for tracking changes in abundance (as opposed to occupancy) across years. Occupancy analyses track whether or not a site was occupied by a species. Abundance is tracked by assessing how the maximum call intensity changes on sites across years, and by how many automated detections are reported from sites across years. Using two independent survey methods, manual and automated, with large sample sizes continues to return reliable results, providing a confident record of site occupancy for most species. There were some data collection issues in 2019, with two ARS units not deployed and two others with late start dates. This did reduce our ability to assess some sites and species. Summaries of 2019 data are shown in Appendices A, B and C, and cumulative data collection result summaries are provided in Appendix E. Since temperature logs show that the threshold of ≥40°F was already exceeded by 1 April in 2019, we recommend a 15 March start date for future data collection.