Adaptive Microbat Management for Balickera Tunnel Restoration Works

Hunter Water Corporation

Hunter Water enlisted the services of Eco Logical Australia to prepare a Species Impact Statement and Management Plan prior to commencing remediation works to repair the structural stability of the Balickera Tunnel, located in the Hunter Valley, NSW.

The 1200m long and 4.5m high tunnel is a key piece of infrastructure for the Lower Hunter region, ensuring primary drinking water supply from the Williams River to Grahamstown Dam.

The tunnel is a significant location for bats, with three of the species roosting there listed as ‘Vulnerable’ under the NSW Biodiversity Conservation Act 2016 (BC Act). Home to one of the most substantial roost sites in NSW for the Little Bent-winged Bat (Miniopterus australis), it also supports ~2% of the Southern Myotis (Myotis macropus) population and is used by the Large Bent-winged Bat (Miniopterus orianae oceanensis). Additionally, it is a roost for the non-threatened Eastern Horseshoe Bat. The remediation work had potential to significantly impact these threatened species of microbats. Before work could commence, an alternate habitat was set up and the bats were temporarily removed from the tunnel.

A team including specialist microbat worked alongside Hunter Water to ensure the bats were safely excluded from the tunnel. Using thermal cameras, ultrasonics and harp traps, data was collected about the bat population and their roost sites.

The exclusion was completed successfully and rapidly, with no bat deaths, likely due to the large number of alternative roost sites and high-quality habitats in the surrounding area, allowing the bats to safely relocate with minimal stress and risk of predation. 

 Internal construction works then proceeded with a double barrier system in place to prevent the bats from re-entering the tunnel. The team monitored the bats monthly and inspected the internal tunnel works throughout the restoration period.