Impacts on Bats by a Supertyphoon vs. Ordinary Typhoons along a Habitat Urbanization Gradient

Abstract

Two major human-caused threats to ecosystems are habitat modification and the increasing frequency and intensity of extreme weather events. To study the combined effect of these threats, the authors used acoustic monitoring of bats along a habitat modification gradient on the island of Okinawa, Japan. During the observation period, the island experienced numerous typhoons and one supertyphoon. Native bat species remained active even at high wind speeds (up to 30 m/s in some cases). Milder typhoons had no observable effect on bat populations, with activity levels fully recovering within a few hours or days. The super typhoon also did not seem to affect bats in fully or partially forested habitats but caused their local disappearance at the urban site, which they have not re-colonized three years after the event. Notably, bats that disappeared at the urban site were species roosting in well-protected places such as caves and concrete structures. In all cases, the biomass of small flying insects and the acoustic activity of insects recovered within days after extreme weather events. Thus, the striking difference between habitats in supertyphoon effects on bats cannot be explained by the super typhoon directly killing bats, destroying their roosting sites, or decreasing the abundance of their prey. The results underscore the importance of preserving natural habitats in areas particularly affected by changing climate and show that the survival of species and ecosystems during the numerous episodes of climate change in the Earth’s history does not necessarily mean their ability to survive the accelerating climate change of our time.