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Roading projects may have adverse effects on indigenous wildlife. In New Zealand the effects of roading on long-tailed bats (Chalinolobus tuberculatus) is an issue and projects have attempted to monitor and mitigate effects on bats populations. However, how to undertake monitoring and mitigation is unclear.

The New Zealand Transport Agency commissioned Wildland Consultants, Landcare Research and AECOM to:

• review the literature on effects and mitigation of roads on bats, and relevant statutory processes
• research road effects on long tailed bats
• develop a framework for managing these effects.

Roads affect bats by severing their flight paths and depleting roosting habitat by removing trees. Most bat road research has quantified effects on behaviour rather than population survival, making prediction of effects difficult. No studies have demonstrated any mitigation options to be effective for bats. Demographic modelling indicated adult female survival is vital for the survival of long-tailed bat populations, and therefore must be preserved by roading mitigation.

Research showed that nightly bat emergence is related to temperature, indicating that bat monitoring should be undertaken when temperatures 1–4 hours after sunset are above 5ºC, and preferably in the 10–17ºC range. Field research also showed a negative relationship between bat activity and night-time traffic volume.

A framework guiding roading projects through the process of consents, ecological monitoring, and mitigation was developed and addresses ecological uncertainty around mitigation options, and describes improved bat monitoring.

Keywords: Chalinolobus tuberculatus, ecology, legislation, long-tailed bat, Mystacina tuberculata, roads, short-tailed bat