Developing tools to detect bats in soil, water, and air

White-nose syndrome is a devastating, emergent fungal disease of cave-hibernating bats. First observed in New York in 2006, the fungus has been progressing westward, crossing the Great Plains in recent years. Early fungus detection and baseline data on bat populations are critical components of disease control and bat population recovery in the face of disease invasion, but these efforts are complicated in western North America due to a general lack of information about where bats overwinter. Thus, natural resource managers in the West have an urgent need for tools to locate wintering bats and assess their vulnerability to invading white-nose syndrome. The goal of this project was to develop assays and proof of concept for the detection of bats (a volant, terrestrial mammal) from environmental samples such as sediment, water, and air.

Approach

Quantitative PCR (qPCR) assays were designed to detect the presence of DNA from big brown bats (Eptesicus fuscus, EPFU) in environmental samples and validated for sensitivity and specificity. To test the proof of concept that bat DNA can be found in environmental samples, air and water samples were collected from a bat enclosure housing 30 EPFU and assayed for EPFU DNA. To assess the use of the assay as a field technique for monitoring, water and sediment samples were collected opportunistically from active season sites and over-wintering roosts.  

Key Findings

• Designed environmental DNA (eDNA) assays for EPFU, a volant, terrestrial mammal, and demonstrated use in environmental samples including sediment, air, and water.
• For the first time, reported eDNA detection of macrobiota from filtered air. eDNA concentrations were low, perhaps due to suboptimal air sampling conditions, e.g. duration of sampling, filter media.
• Did not detect EPFU at an occupied winter hibernaculum during winter sampling in water. Sampling from flowing stream may be insufficient temporal window for DNA deposition when bats are dormant.
• Found consistent results between paired eDNA and mist net results at a single site which is promising for active season monitoring.
• Results of the study were published in Biological Conservation in 2021 and presented to stakeholders at the 2020 White Nose Syndrome National Meeting.

The eDNA approach for monitoring is well developed for aquatic organisms that spend their life cycle in water, but application to a volant, terrestrial mammal is a frontier. The products of this research, eDNA assays for bats and proof of concept, are a promising first step in the development of a tool to detect bats noninvasively on the landscape. Future research will focus on identifying where bat DNA is most likely to be concentrated in the environment and designing protocols to maximize DNA recovery for reliable detection and monitoring.