Reaching New Heights: Arboreal Camera Trapping Provides New Insights on the Ecology of Gray Treefrogs (Hyla versicolor)

Abstract. The ecology of many arboreal ectotherms is poorly understood because of access constraints to the forest canopy. For example, despite their common name, Gray Treefrogs (Hyla versicolor) are understudied in arboreal habitats. Advancements in camera trap technology and tree-climbing techniques have created new opportunities to study arboreal species. Using arboreal camera trapping and time-lapse photography, we implemented the first study of H. versicolor behavior in the canopy. We examined seasonal and diel patterns of activity, microhabitat use, and effects of relative humidity and temperature on H. versicolor activity in eastern white pine (Pinus strobus) canopies. We installed camera traps at three research sites in northern Wisconsin, USA, spanning a 57-km north–south transect, and maintained them for multiple years. We detected H. versicolor events, of all sex–age classes, at two of our research sites. Use of time-lapse photography significantly improved our ability to detect H. versicolor in the canopy. Hyla versicolor individuals were active in the canopy every year of the study (2015–18), but predominantly during the summer, and peak diel activity occurred predominantly during the night (between 2100 and 2300 h). Hyla versicolor activity significantly increased as relative humidity and temperature increased. Hyla versicolor individuals were significantly more active in the upper canopy compared with other canopy locations and selected for the top side of branches. Our results highlight that H. versicolor frequent arboreal habitats of P. strobus canopies. Although further research is needed, our work lays a foundation of H. versicolor ecology within the canopy. This research also demonstrates the feasibility of using arboreal camera traps with time-lapse settings to study ectotherms in forest canopies.