Conduct Netting Surveys of the park and continue with bat acoustic monitoring and emergence counts
PI: Cindy Heyd
Pictured Rocks National Lakeshore (PRNL) monitored bat populations through a mist-netting project conducted by Dr. Kurta from Eastern Michigan University and through acoustic monitoring and emergence counts by the park. Both projects were negatively affected by atypical weather conditions, which influenced insect populations and, therefore, bat foraging patterns. Insect populations never completely rebounded to "normal" during the summer. Bat populations, based on comparison to 2015 numbers, seem to have declined substantially, likely due to white-nose syndrome (WNS). Northern long-eared bats were not detected by either acoustics or netting over most of the park in 2016.
Dr. Kurta netted at locations throughout the park; he thought the number of bats caught was low, both due to WNS and possibly other causes. The most commonly caught bat was the silver-haired bat. They were able to find one maternity colony of northern long-eared bats. The bats netted in the park were mostly male. Bats with damaged wing membranes were caught. Dr. Kurta is planning on coming back next summer to conduct further investigations on bats here in PRNL.
PRNL staff conducted acoustic monitoring and emergence counts. Acoustic monitoring was conducted at the base points, and then additional points were able to be done due to additional staff provided by WNS funding. Very preliminary comparison of results from 2015 and 2016 indicate that many units placed at the same locations picked up fewer bats this year compared to last year. The silver-haired and hoary bats are the most common species detected by the acoustic units. The northern long-eared bat was down significantly and was rarely detected, but all species were lower with the exception of the big brown bat. For some unknown reason, big brown bats increased; there is a question if the analysis software is confusing silver-haired and big brown bat calls, which might explain the increase. With only 2 years of data at most points, there is a lot of “noise” in the data, and results should be interpreted cautiously.
Emergence counts were down from 2015; one location, a maternity colony of little brown bats and a small number of northern long-eared bats, were down significantly. Only 52 individuals were counted in 2016, in comparison to 160 in 2015 and 300 in 2014.
Bat Interpretative and Educational information has been well received. This year PRNL Interpretative staff created a bat curriculum and obtained props for their program. This program is geared toward 4th graders.